District Cooling Systems

DEPARTMENT OF TECHNOLOGY AND BUILT ENVIRONMENT

TECHNOLOGICAL AND ECONOMIC EVALUATION OF DISTRICT COOLING WITH ABSORPTION COOLING SYSTEMS IN GÄVLE (SWEDEN)

Elixabet Sarasketa Zabala

June 2009

Master’s Thesis in Energy Systems

uuir Master Programme in Energy Systems Examiner: Ulf Larsson Supervisor: Åke Björnwall

Preface

This investigation, as final Thesis Project of Master in Energy Systems (University of Gävle), was started to carry out in February, in collaboration with the company Gävle Energi AB. Many people have been involved answering my questions, providing me with information and so forth; some of those are mentioned below.

First of all, I would like to thank Åke Björnwall, my supervisor at Gävle Energi AB, very much for his attention, help and support. His knowledge, comments, guidance and advices have been essential for the development of my work. Needless to say that I have learnt a lot from him.

Secondly, I would like to thank the rest of workers at Gävle Energi AB, who have done everything they can to help me, in addition to make pleasant my stay in the company.

I would also like to thank Ulf Larsson at the University of Gävle for his help. Furthermore, I am very grateful for all information I have received from other companies.

Finally, I do not forget the invaluable support of my mother, Rosa, during all my studies.

No one mentioned, no one forgotten.

Gävle, June 2009

Elixabet Sarasketa Zabala

Abstract

Gävle Energi AB is a company which produces electricity as well as heat that is delivered through a district heating network in the municipality of Gävle. Apart from that, as cooling demand is large when seen from a global perspective, at present it is building a district cooling network based on refrigerant compressor technology with the idea of replacing less efficient individual HVAC systems in the city center.

High electricity prices lead to reduce its use as far as possible, so it is also needed to consider absorption systems as cooling technology. This way, the main aim of this thesis is to analyze possible benefits with the use of heat driven absorption chillers compared with conventional vapour compressor chillers.

For carrying out this investigation, first of all background and literature study have been essential. As a result, information about cooling technologies, district energy and cogeneration plants is gathered in this work.

The research is focused on three areas of the victinity of Gävle: city center, Kungsbäck and Johannesbergsvägen.

In the first area, Gävle Energi AB might take the opportunity of using a new ORC plant in biomass based cogeneration system that Bionär is planning to build at LEAF, turning it into a trigeneration plant. So how bigger the installation should be (according to the expected cooling demand that has been calculated in the earliest steps) and the profits related to extra electricity production are estimated in this study, in addition to examine the absorption chillers to be introduced and their operational conditions.

On the other hand, Mackmyra whisky factory, which is in Valbo nowadays, is going to build a new plant in Kungsbäck. Likewise, it is considering

that extra steam might be produced to fire absorption chillers and fulfil the cooling demand of the hospital (Gävle Sjukhus), technological park (Teknikparken) and university (Högskolan i Gävle), which are located in this area. Like this, the same methodology as for LEAF has been followed for making decisions.

Finally, there is Johannesbergsvägen area, where Johannes CHP plant is (a description of the plant is included in the Appendix) and which is runned by Gävle Energi AB. This plant is shut down in summer, as the demand for district heating is low, and hence, electricity production, from which the company makes a profit, is cut and restricted. A good solution to increase electricity output in warm periods is to introduce absorption cooling technology, as it is run on steam or hot water. Thus, Johannes could be the third trigeneration plant in Gävle that would supply Hemlingby shopping centers (which are located less than two kilometers far away from the production site) with cooling. Thus, the task has been also to decide on installations and gauge the profits.

Next Table 0. gathers together costs, amount of heat that would be demanded to produce and accordingly generated electricity in each of the three production sites. It has been decided that double-effect chillers sets in the first two cases and single-effect hot-water fired absorption cooling machines in the last one might be introduced.

Table 0. Costs of absorption cooling installations, extra heat to be produced for the absorption chillers and extra electricity output in the three studied sites PRODUCTION OPERATIONAL HEATING ELECTRICITY SITE &TOTAL INVESTMENT COSTS DEMAND PRODUCTION COOLING COST [SEK] [SEK/year] [MWh/year] [MWh/year] LOAD LEAF 22 627 000 4 753 485 17 977 4 135 21 385 MWh/year MACKMYRA 17 700 000 2 504 835 7 819 1 173 9 298 MWh/year JOHANNES 8 800 000 3 561 396 10 460 3 033 8 496 MWh/year

Furthermore, explanations and calculations regarding distribution systems are presented, as these are also a component of district cooling systems. Nevertheless, they are not taken into consideration for final decisions, since necessary pumps and piping system would be the same in case of using vapour compressor chillers for cooling production.

Lastly, it has been come to the conclusion that a sustainable energy system for Gävle for fulfilling the cooling demand can be the erection of district cooling networks with trigeneration plants by producing cooling in heat driven absorption cooling machines. Despite larger investment cost of absorption systems compared to compression ones, total costs after roughly five years are lower. Moreover, electric coefficient of performance is about 23% higher for the absorption cooling technology and there is a great electricity output too, which makes possible to reduce electrical loads, to use the biofuel in an effective way and, last but not least, to decrease global carbon dioxide emissions.

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION ...... 1

1.1. BACKGROUND ...... 2 1.1.1. COOLING AND ITS PRODUCTION ...... 2 1.1.2. GÄVLE ENERGI AB AND ITS PLANS FOR THE FUTURE...... 3

1.2. PURPOSE ...... 4

1.3. SCOPE...... 4

1.4. LIMITATIONS ...... 5

1.5. METHOD ...... 5

1.6. OUTLINE OF THE THESIS...... 6

CHAPTER 2. COOLING SYSTEM TECHNOLOGIES ...... 8

2.1. REFRIGERANT COMPRESSOR INSTALLATIONS ...... 10 2.1.1. COMPRESSOR AND SYSTEM EFFICIENCY ...... 12

2.2. ABSORPTION COOLING INSTALLATIONS ...... 13 2.2.1. CONSIDERATIONS FOR DIMENSIONING ABSORPTION CIRCUITS...... 17 2.2.2. WORKING FLUID ...... 18

2.2.2.1. WATER/ LITHIUM BROMIDE (H2O/ LiBr) ...... 19

2.2.2.2. AMMONIA/WATER (NH3/ H2O) ...... 20 2.2.2.3. COMPARISON BETWEEN WATER/ LITHIUM BROMIDE AND AMMONIA/WATER SOLUTIONS...... 21 2.2.3. PRIMARY ENERGY ...... 25 2.2.4. TYPES OF ABSORPTION CHILLERS ...... 26 2.2.4.1. SINGLE-EFFECT ABSORPTION CHILLERS ...... 27 2.2.4.2. DOUBLE-EFFECT ABSORPTION CHILLERS ...... 28

2.3. REFRIGERANT COMPRESSOR TECHNOLOGY VERSUS ABSORPTION COOLING TECHNOLOGY ...... 30

CHAPTER 3. DISTRICT COOLING SYSTEM ...... 35

3.1. PRODUCTION ...... 37 3.1.1. COGENERATION. BENEFITS WITH ABSORPTION COOLING ...... 37

TABLE OF CONTENTS

3.2. COOLING DISTRIBUTION SYSTEM...... 39 3.2.1. PIPING NETWORK ...... 39 3.2.2. MATERIALS FOR THE PIPES ...... 40

CHAPTER 4. PROCESS ...... 41

4.1. GATHERING OF INFORMATION ABOUT EXISTING INSTALLATIONS AND PRESENT SITUATION ...... 42 4.1.1. STEAM BOILERS AT LEAF AND KAPPA ...... 42 4.1.2. BIOFUELED JOHANNES CHP PLANT ...... 44 4.1.3. MACKMYRA ...... 46 4.1.4. REFRIGERATION COMPRESSOR COOLING PROJECT ...... 47

4.2. GATHERING OF DATA: CUSTOMERS. LOAD REQUIRED AND DISTANCES ...... 48

4.3. ANALYSIS OF ABSORPTION COOLING PLANTS ...... 51 4.3.1. ABSORPTION CHILLERS ...... 51 4.3.3.1. STUDY OF THE OPERATIONAL CONDITIONS ...... 52 4.3.2. REST OF THE EQUIPMENTS ...... 52

CHAPTER 5. RESULTS ...... 56

5.1. PRODUCTION PLANTS ...... 57 5.1.1. LEAF ...... 57 5.1.1.1. OPERATIONAL CONDITIONS ...... 57 5.1.1.2. COSTS ...... 58 5.1.1.2.1. INVESTMENT COSTS ...... 58 5.1.1.2.2. OPERATIONAL COSTS ...... 59 5.1.1.2.3. TOTAL COSTS ...... 59 5.1.2. MACKMYRA ...... 61 5.1.2.1. OPERATIONAL CONDITIONS ...... 61 5.1.2.2. COSTS ...... 62 5.1.2.2.1. INVESTMENT COSTS ...... 62 5.1.2.2.2. OPERATIONAL COSTS ...... 62 5.1.2.2.3. TOTAL COSTS ...... 63 5.1.3. JOHANNES ...... 64 5.1.3.1. OPERATIONAL CONDITIONS ...... 64 5.1.3.2. COSTS ...... 64 5.1.3.2.1. INVESTMENT COSTS ...... 65 5.1.3.2.2. OPERATIONAL COSTS ...... 65 5.1.3.2.3. TOTAL COSTS ...... 65 5.1.4. SENSITIVITY ANALYSIS ...... 67 5.1.4.1. LEAF ...... 67 5.1.3.2. MACKMYRA ...... 69

TABLE OF CONTENTS

5.1.3.2. JOHANNES ...... 71

5.2. COMPRESSION TECHNOLOGY VERSUS ABSORPTION TECHNOLOGY. COMPARISON FOR LEAF PRODUCTION SITE...... 72

5.3. DISTRIBUTION SYSTEM ...... 75 5.3.1. INSTALLATION ...... 75 5.3.3. COST OF THE MAIN PIPING NETWORKS ...... 75

CHAPTER 6. DISCUSSIONS ...... 76

6.1. PRODUCTION PLANTS ...... 77

6.2. MOST PROFITABLE TECHNIQUE FROM ECONOMIC POINT OF VIEW. SUSTAINABILITY ...... 80

6.3. COOLING DEMAND VERSUS COSTS AND BENEFITS OF ABSORPTION COOLING TECHNOLOGY ...... 83 6.3.1. ELECTRICITY PRODUCTION AND CONSUMPTION ...... 83 6.3.2. COSTS AND PROFITS. THE BEST OPTIONS ...... 84

CHAPTER 7. CONCLUSIONS ...... 86

REFERENCES ...... 88

APPENDICES ...... 92

Appendix 1. PLANNED REFRIGERANT COMPRESSION INSTALLATION ...... 93

A1.1. INSTALLATION ...... 93 A1.2. COOLING LOAD ...... 99 A1.3. INPUT LOAD AND COSTS ...... 100 A1.4. TOTAL COSTS ...... 102 A1.5. PAY-BACK TIME FOR THE INVESTMENTS... 103

Appendix 2. EXPECTED COOLING DEMAND ...... 104

III

TABLE OF CONTENTS

Appendix 3. SPECIFICATIONS AND CALCULATIONS REGARDING ABSORPTION COOLING INSTALLATIONS ...... 108

A3.1. ABSORPTION CHILLERS...... 108 A3.1.1. MODELS AND THEIR CHARACTERISTICS ...... 108 A3.1.2. INVESTMENT COSTS ...... 118 A3.1.3. OPERATIONAL CONDITIONS ...... 119 A3.2. THE REST OF EQUIPMENTS ...... 131

Appendix 4. MAPS OF CUSTOMERS AND DISTANCES FROM THE PRODUCTION SITES ...... 133

Appendix 5. CALCULATIONS ABOUT DIMENSIONS OF PIPES, DISTRIBUTION PUMPS AND THEIR COSTS ...... 140

A5.1. DIMENSIONING ...... 140 A5.2. COSTS ...... 146

Appendix 6. FALUN COOLING PROJECT: A REFERENCE ...... 150

A6.1. INSTALLATION ...... 150 A6.2. TOTAL COSTS...... 152

Appendix 7. EXTRA INFORMATION ABOUT JOHANNES POWER PLANT...... 153

LIST OF FIGURES

Figure 1. Refrigerant compression cycle ...... 10 Figure 2. Temperature-Entropy (T-s) diagram for a Vapour-Compression Refrigeration Cycle ...... 11 Figure 3. Scheme of basic absorption cycle ...... 14 Figure 4. Schematic of the fundamental absorption refrigeration system ...... 17 Figure 5. Ammonia/Water absorption cycle ...... 20 Figure 6. Crystallization temperatures of water/lithium bromide solution against the mass concentration of lithium bromide ...... 21 Figure 7. Maximum system pressures against the condenser temperature ...... 22 Figure 8. Minimum system pressures against the evaporator temperature ...... 23 Figure 9. COP of the absorption systems against the condenser temperature (heat exchanger efficiency 0,6) ...... 24 Figure 10. COP of the absorption systems against the generator temperature (heat exchanger efficiency 0,6) ...... 24 Figure 11. COP of the absorption systems against the evaporator temperature (heat exchanger efficiency 0,6) ...... 25 Figure 12. Cooling cycle schematic ...... 27 Figure 13. Double-Effect Water/Lithium Bromide Absorption Chiller Schematic ...... 28 Figure 14. Sketch for a double effect absorption heat pump in a log pressure- temperature diagram ...... 29 Figure 15. Comparison between compression and absorption technologies using ammonia as refrigerant and cooling water with a temperature of 25 ºC ...... 31 Figure 16. Components of district cooling systems ...... 36 Figure 17. District cooling system (or district heating system) ...... 36 Figure 18. An schematic of cogeneration process that shows the consumed and produced power in the whole system ...... 37 Figure 19. Illustration of a CHP plant connected to a district heating network ... 38 Figure 20. Energy efficiency of ORC units in cogeneration applications ...... 43 Figure 21. ORC plant in biomass based cogeneration system ...... 43 Figure 22. Johannes CHP plant before 2003 ...... 44 Figure 23. Production of heat (for District Heating) and electricity at Johannes ...... 45 Figure 24. Existing electric boiler in Mackmyra ...... 46 Figure 25. Existing and planned boilers at Mackmyra ...... 47 Figure 26. Three cooling production and customer sites and main pipes ...... 49 Figure 27. Cooling power to be produced in different sites during the year ...... 53 Figure 28. Typical piping diagram of an absorption system ...... 56 Figure 29. Graph that shows the breakdown of total costs for 10 years at LEAF ...... 60

LIST OF FIGURES

Figure 30. Graph that shows the breakdown of total costs for 10 years in Mackmyra production site ...... 63 Figure 31. Graph that shows the breakdown of total costs for 10 years in Johannes production site ...... 66 Figure 32. Comparison of cooling installations with absorption and compression machines at LEAF ...... 74 Figure 33. Increased heat load for the three absorption plants and the possible extra electricity that would be produced ...... 79 Figure 34. Increased heat and electricity load in the probable Johannes trigeneration plant ...... 79 Figure 35. Required operational conditions of the boiler for the cooling plant at Johannes ...... 80 Figure 36. Comparison of total costs for ten years for the different cooling production technologies at LEAF ...... 81 Figure 37. Electricity production and consumption according to the cooling demand in three different scenarios ...... 84 Figure 38. Costs and profits (due to electricity production) according to the cooling demand in three different scenarios ...... 84 Figure A1. 1. Draft of the whole compression installation...... 90 Figure A1. 2. Draft of the devices of the compression installation...... 90 Figure A1. 3. Maintenance costs in the course of time ...... 99 Figure A3. 1. Water streams (steam and DH) at Johannes CHP plant ...... 111 Figure A3. 2. Cooling demand load curve (2008) divided in periods according to the power needed to be produced ...... 116 Figure A4. 1. Map of the city center with the main pipe that leaves LEAF production site and its length ...... 130 Figure A4. 2. Map with the customers, pipes and distances for Mackmyra production site ...... 132 Figure A4. 3. Map with the customers for Johannes production site, pipe and its length ...... 134 Figure A4. 4. Map of the shopping centers under construction in Hemlingby ... 135 Figure A4. 5. Map of the future residential area close to Johannes plant ...... 136 Figure A5. 1. SBI monogram showing the parameters of the different pipes .... 140 Figure A5. 2. Differential pressures in a direct return distribution system with one terminal unit ...... 141 Figure A5. 3. Piping excavation section ...... 143 Figure A5. 4. Distribution system cost split up in its components and their contribution to the total cost...... 145 Figure A6. 1. Draft of the whole cooling installation in Falun ...... 147 Figure A7. 1. Scheme of Johannes CHP plant ...... 150 Figure A7. 2. Fuel storage and conveyor belt carrying biofuel to the boiler at Johannes ...... 151 Figure A7. 3. Bubble Fluidized Bed (BFB) boiler of Johannes CHP plant ...... 152

LIST OF FIGURES

Figure A7. 4. Illustrative drawing of Olga turbine and components ...... 153 Figure A7. 5. Olga turbine on the left side and heat exchangers on the right Side. Johannes CHP plant ...... 153 Figure A7. 6. Schematic of the FGC at Johannes ...... 154 Figure A7. 7. Detailed scheme of the condensate treatment plant at Johannes .. 154

VII

LIST OF TABLES

Table 1. Production sites and customers ...... 4 Table 2. Absorption working fluids´ properties ...... 23 Table 3. Comparison of parallel and series flow for double-effect water/lithium bromide cycles ...... 29 Table 4. Energy saving with cogeneration for α = 0,54 ...... 33 Table 5. Summary of characteristics for cooling options ...... 34 Table 6. Comparison between two 1000kW chillers ...... 34 Table 7. Different types of plants using a steam boiler and their characteristics ...... 38 Table 8. Cooling load demand at each site ...... 50 Table 9. Possibilities to fulfill the cooling demand in the city center by using steam-fired absorption chillers ...... 51 Table 10. Possibilities to fulfill the cooling demand in Kungsbäck by using steam-fired absorption chillers ...... 52 Table 11. Possibilities to fulfill the cooling demand corresponding to Johannes plant ...... 54 Table 12. Cooling that should be produced for different sites during the year .... 55 Table 13. Power and steam demand of different chillers sets for the required cooling load at LEAF during the year ...... 57 Table 14. Biofuel (for producing steam), electricity and water consumption. LEAF ...... 58 Table 15. Investment costs [SEK] for LEAF ...... 58 Table 16. Operational costs at LEAF ...... 59 Table 17. Total costs of LEAF absorption cooling plants for 10 years ...... 59 Table 18. Power and steam demand of different chillers sets for the required cooling load in Mackmyra production during the year ...... 61 Table 19. Biofuel (for producing steam), electricity and water consumption. Mackmyra ...... 61 Table 20. Investment costs [SEK] for Mackmyra ...... 62 Table 21. Operational costs in Mackmyra production site ...... 62 Table 22. Total costs of Mackmyra absorption cooling plants for 10 years ...... 63 Table 23. Power and hot water demand of chillers set for the required cooling load at Johannes during the year ...... 64 Table 24. Biofuel (for producing steam), electricity and water consumption. Johannes ...... 64 Table 25. Investment costs [SEK] for Johannes...... 65 Table 26. Operational costs in Johannes production site ...... 65 Table 27. Total costs of Johannes absorption cooling plant for 10 years ...... 65 Table 28. Operational conditions of different chillers sets at LEAF during the year when the cooling demand is 10% higher than the estimated one ...... 67

VIII

LIST OF TABLES

Table 29. Total costs of LEAF absorption cooling plants for 10 years when the cooling demand is 10% higher than the estimated one ...... 67 Table 30. Operational conditions of different chillers sets at LEAF during the year when the cooling demand is 10% lower than the estimated one .. 68 Table 31. Total costs of LEAF absorption cooling plants for 10 years when the cooling demand is 10% lower than the estimated one ...... 68 Table 32. Operational conditions of different chillers sets in Mackmyra production site during the year when the cooling demand is 10% higher than the estimated one ...... 69 Table 33. Total costs of Mackmyra absorption cooling plants for 10 years when the cooling demand is 10% higher than the estimated one ...... 69 Table 34. Operational conditions of different chillers sets in Mackmyra production site during the year when the cooling demand is 10% lower than the estimated one...... 70 Table 35. Total costs of Mackmyra absorption cooling plants for 10 years when the cooling demand is 10% lower than the estimated one ...... 70 Table 36. Operational conditions of different chillers sets in Johannes production site during the year when the cooling demand is 10% higher than the estimated one ...... 71 Table 37. Total costs of Johannes absorption cooling plants for 10 years when the cooling demand is 10% higher than the estimated one ...... 71 Table 38. Operational conditions of different chillers sets in Johannes production site during the year when the cooling demand is 10% lower than the estimated one...... 71 Table 39. Total costs of Johannes absorption cooling plants for 10 years when the cooling demand is 10% lower than the estimated one ...... 71 Table 40. Operational conditions of the existing cooling project but with absorption machines ...... 73 Table 41. Power and steam demand of chillers set for the required cooling load in the existing cooling project but with absorption machines ...... 73 Table 42. Operational costs in the existing cooling project but with absorption machines ...... 73 Table 43. Total costs of the existing cooling project but with absorption machines for 10 years ...... 73 Table 44. Data about the distribution systems ...... 75 Table 45. Cost of the distribution systems ...... 75 Table 46. Operational conditions and costs of distribution pumps ...... 75 Table 47. Most adequate chillers and costs & profits for the three production sites ...... 78 Table 48. Annual benefits of absorption cooling technology at LEAF after 10 years ...... 81

LIST OF TABLES

Table R. 1. Information about personal contacts ...... 88 Table A1. 1. Pump specifications of compression cooling installation I ...... 92 Table A1. 2. Pump specifications of compression cooling installation II ...... 93 Table A1. 3. Pump specifications of compression cooling installation III ...... 93 Table A1. 4. Pump specifications of compression cooling installation IV ...... 93 Table A1. 5. Pump specifications of compression cooling installation V ...... 93 Table A1. 6. Pump specifications of compression cooling installation VI ...... 94 Table A1. 7. Pump specifications of compression cooling installation VII ...... 94 Table A1. 8. Pump specifications of compression cooling installation VIII ...... 94 Table A1. 9. Vapour Compressor chillers specifications I ...... 94 Table A1. 10. Vapour Compressor chillers specifications II ...... 95 Table A1. 11. Vapour Compressor chillers specifications III ...... 95 Table A1. 12. Heat exchanger specifications of compression cooling installation ...... 95 Table A1. 13. Operational conditions of VKA1 and VKA2 compressors (YRWCWCT3550C) in time steps ...... 96 Table A1. 14. Operational conditions of VKA4 and VKA5 compressors (YKKKKLH95CQF) in time steps ...... 96 Table A1. 15. Operating time for cooling delivering during the year ...... 96 Table A1. 16. Power needed in the compression cooling installation during the year ...... 97 Table A1. 17. Input load VKA1 and VKA2 compressors (YRWCWCT3550C) in time steps...... 98 Table A1. 18. Input load VKA4 and VKA5 compressors (YKKKKLH95CQF) in time steps...... 98 Table A1. 19. Total input load and operating costs in the compression cooling installation ...... 99 Table A1. 20. Costs of the compressor refrigerant system ...... 99 Table A1. 21. Pay-back times for the compression installation ...... 100 Table A1. 22. Total costs for the refrigeration compression system for the first 10 years ...... 100 Table A2. 1. Cooling demand of possible future customers in the city center and additional data ...... 101 Table A2. 2. Customers and their cooling demand in Kungsbäck ...... 103 Table A2. 3. Cooling demand for Johannes production site ...... 104 Table A3. 1. Production data and pressure of the first steam stream extracted from the turbine ...... 112 Table A3. 2. Price comparison of single- and double-effect units ...... 115 Table A3. 3. Investment costs for different absorption chiller units ...... 116 Table A3. 4. Average city center´s cooling demand in time steps for 2008 ...... 117 Table A3. 5. Cooling load to be produced and working power of different chillers (double- and single- effect) at LEAF during the year ...... 118 Table A3. 6. Cooling power to be supplied to the chillers at LEAF during the year ...... 118

LIST OF TABLES

Table A3. 7. Cooling load to be produced and working power of different chillers (double- and single- effect) at LEAF during the year when the cooling demand is 10% higher than the estimated one ...... 119 Table A3. 8. Cooling power to be supplied to the chillers at LEAF during the year when the cooling demand is 10% higher than the estimated one ...... 119 Table A3. 9. Cooling load to be produced and working power of different chillers (double- and single- effect) at LEAF during the year when the cooling demand is 10% lower than the estimated one ...... 120 Table A3. 10. Cooling power to be supplied to the chillers at LEAF during the year when the cooling demand is 10% lower than the estimated one ...... 120 Table A3. 11. Cooling load to be produced and working power of different chillers (double- and single- effect) in Mackmyra production site during the year ...... 121 Table A3. 12. Cooling power to be supplied to the chillers during the year and necessary cooling towers in Mackmyra production site ...... 121 Table A3. 13. Cooling load to be produced and working power of different chillers (double- and single- effect) in Mackmyra production site during the year when the cooling demand is 10% higher than the estimated one ...... 122 Table A3. 14. Cooling power to be supplied to the chillers during the year and necessary cooling towers in Mackmyra production site when the cooling demand is 10% higher than the estimated one...... 122 Table A3. 15. Cooling load to be produced and working power of different chillers (double- and single- effect) in Mackmyra production site during the year when the cooling demand is 10% lower than the estimated one ...... 123 Table A3. 16. Cooling power to be supplied to the chillers during the year and necessary cooling towers in Mackmyra production site when the cooling demand is 10% lower than the estimated one ...... 123 Table A3. 17. Cooling load to be produced and working power of different chillers in Johannes production site during the year...... 124 Table A3. 18. Cooling power to be supplied to the chillers during the year and necessary cooling towers in Johannes production site ...... 125 Table A3. 19. Cooling load to be produced and working power of different chillers in Johannes production site when the cooling demand is 10% higher than the estimated one ...... 125 Table A3. 20. Cooling power to be supplied to the chillers in Johannes production site during the year when the cooling demand is 10% higher than the estimated one ...... 126 Table A3. 21. Cooling load to be produced and working power of different chillers in Johannes production site when the cooling demand is 10% lower than the estimated one ...... 126

LIST OF TABLES

Table A3. 22. Cooling power to be supplied to the chillers in Johannes production site during the year when the cooling demand is 10% lower than the estimated one ...... 127 Table A3. 23. Required cooling towers and heat exchangers´ technical data..... 128 Table A5. 1. Dimensioning of pipes and pressure drop (part I) ...... 137 Table A5. 2. Dimensioning of pipes and pressure drop (part II) ...... 138 Table A5. 3. PE Pressure Pipes for water supply: EN 12201, ISO 4427 ...... 142 Table A5. 4. Data of the pipes needed ...... 143 Table A5. 5. Values of parameters C and B for the required dn ...... 144 Table A5. 6. Total cost of the pipes ...... 144 Table A5. 7. Calculation of the pipes´ costs ...... 145 Table A5. 8. Needed distribution pumps and their cost ...... 146 Table A6. 1. Reference specifications about absorption chiller in Falun ...... 148 Table A6. 2. Investment costs for different installations in Falun ...... 149 Table A6. 3. Input electric power in Falun installations ...... 149 Table A7. 1. Characteristics of the obtained outputs at Johannes ...... 153

XII

CHAPTER 1

Introduction

This chapter is a definition of the thesis, which describes the issues to be studied and the reasons for their investigation, as well as the main purpose, scope, limitations and so forth.

In general terms, the task can be summed up as the evaluation of technological and economic possibilities regarding district cooling with absorption cooling technology at three specific sites in the victinity of Gävle.

1.1. BACKGROUND

1.1.1. COOLING AND ITS PRODUCTION

It is a fact that cooling demand is as high as or even higher than heating demand, since it is needed for both thermal comfort and many industrial processes and, in addition, it is required more energy for producing cooling than heating. Hence, production of cold could be very profitable for energy companies when it is a part of the existing energy system.

District cooling system (DCS) offers massive and collective cooling energy production, which is higher in efficiency than the conventional plants at individual premises, and allows users to utilise building space more effectively [1]. Generally, the chilled water for pipeline distribution is produced by refrigerant compressor technique; nonetheless, it is needed to face up to a large electricity consumption, which involves a large expense due to the deregulation of the european electricity market.

In 2004 Sweden became part of a common european electricity market and swedish plant will therefore meet higher european prices, which will lead to a

Chapter 1. INTRODUCTION

precarious scenario because of its intensive utilization of electricity [2]. Consequently, the use of electricity has to be decreased, for instance by changing energy carrier when it is used for non-electricity specific purposes. To reach this target, the choice of absorption facilities as cooling technology is clear.

Absorption cooling sytem uses heat as fuel, which make it possible to combine with cogeneration plants and make the most of surplus heat. Moreover, it is especially benefitial in summer periods when there is a large amount of waste heat and electricity generation needs to be therefore reduced or stopped.

1.1.2. GÄVLE ENERGI AB AND ITS PLANS FOR THE FUTURE

Gävle Energi AB is an energy company that belongs to Gävle community and it develops, produces and sells products and services in energy and communication with great view of the environment and nature. The company owns and runs most of the electricity as well as district heating network in the municipality of Gävle.

Gävle Energi AB not only ensures short-term goals but it has always long- term objectives to contribute actively to the Gävle region's development. Thus, as cooling demand is large when seen from a global perspective, it is building a district cooling network which will be finished in a near future. In a first step, the planned production of cold is based on refrigerant compressor technology and at present, it is thinking of future possibilities of using absorption cooling systems because of its low operational costs.

This way, the company wants to study the construction of district cooling systems by absorption cooling facilities for three small islands as large customers: city center, Hemlingby shopping centers and, finally, Kungsbäck area (university, hospital and technological park as a whole). Power for producing cold for these

Chapter 1. INTRODUCTION

sites could be supplied by steams boilers at LEAF, Johannes and future Mackmyra whisky factory respectively.

Table 1. Production sites and customers NEARBY LARGE SITE CUSTOMER 1) Planned biofueled ORC plant at LEAF Planned network in the central production site in Gävle of Gävle. 2) Planned production site of Mackmyra HiG, Gävle general hospital and whiskys in Kungsbäck technological park 3) Biofueled steam boiler at Johannes CHP plant Hemlingby shopping centers

It needs to be underlined that customers and areas have been chosen according to the possible disposal production sites. If other adequate steam boilers were, perhaps Gävle Energi AB might think about other customer islands in the victinity of Gävle.

1.2. PURPOSE

The aim of this thesis is to study economic and technological aspects of absorption cooling in the three cases already presented (see Table 1.). Therefore, it is required to decide needed size of installations in order to analyze costs and profits.

1.3. SCOPE

A district cooling system consists of three primary components: central plant (production), distribution system and customer system (market). The first two will be studied, starting from technological aspects and going through economic ones after.

Chapter 1. INTRODUCTION

It should be investigated the following with regards to each of the three sites in Gävle: - Operational conditions (maximum/minimum power, hours of operation per year and so forth). - Operational and investment cost of absorption system installations. - Cost of distribution systems by only concentrating on costs of main pipes (from production plant to customer substations). - Most economical size of installations.

1.4. LIMITATIONS

Even though more aspects ought to be taken into account, the matters mentioned in the scope are at focus and neither investment costs of steam boilers nor costs regarding customer substations should be considered. On the one hand, boilers either already exist or will be built anyway (this way, operational costs of producing steam for absorption chillers are also not pondered because boilers are working anyway and extra costs are negligible). On the other hand, it is very difficult to estimate the cost of customer facilities and furthermore, they will be the same whichever way the cold is produced (the main aim is to compare cooling production systems).

Moreover, it has to be underlined that the research is only centred on those three areas of the municipality.

1.5. METHOD

First of all, the issues of the thesis and reasons why they are interesting to investigate have been analyzed. In this way, the project has been specified and tasks for carrying it out have been defined in depth. Afterwards, a literature study

Chapter 1. INTRODUCTION

has been done to get enough knowledge about subjects: cooling technologies, district cooling systems and CHP plants using biofueled steam boilers.

Secondly, in the project´s early stages, it has been got in touch with consultants of Gävle Energi AB and experts at absorption cooling (Ramboll) and refrigerant compressor (SWECO) technologies for gathering together information about real installations and equipments in the market, as well as for examining them from different points of view.

Once different parts have been understood, it has been gone ahead with the thesis by concentrating on the real cases the investigation had to be focused on. Like this, it has been asked for data about customers´ cooling demand (load required), distribution distances and so on to make a first estimation of needed size of the installations and thus, the operational conditions.

The next step has been to decide on production plant size, for later weigh costs up. This has let profits of the new technology be known as regards extra electricity production and use of steam for cooling production. And, to finish with the production part, the compression installation has been compared with absorption one and, in addition, a sensitivity analysis, which ranges over size of equipments, costs and profits, has been done.

Last but not least, decisions regarding distribution systems have been made and costs has been also assessed.

1.6. OUTLINE OF THE THESIS

Chapter 2 explains the existing two main cooling production systems, refrigerant compressor and absorption technologies, but it is mainly concentrated on absorption installations. Then, it is finished with a comparison between them and advantages as well as disadvantages are discussed.

Chapter 1. INTRODUCTION

In Chapter 3 district cooling systems are presented. Section 3.1. describes production plants shortly, that is, what cogeneration or a CHP plant is and profits of working with them. Section 3.2. is about cooling distribution systems, which covers both characteristics of the piping networks (Section 3.2.1.) and type of pipes which are going to be used (Section 3.2.2.).

Chapter 4 studies thoroughly the real cases. This way, firstly it is presented the current situation and future plans (Section 4.1.). Thereafter, it is explained how decisions about production sites and customer areas have been made, in addition to sum up collected data about cooling demands and estimations about distances (Section 4.2.). Finally, data researchs and analysis regarding absorption cooling plants are included (Section 4.3.).

In Chapter 5 the obtained results are shown. Firstly, operational conditions and total costs of all production sites are gathered together (Section 5.1.). Moreover, Section 5.2. presents compression and absorption cooling systems´ comparison based on the existing project at LEAF. Lastly, Section 5.3. decribes the distribution systems and the costs they involve.

To finalize, there is the most important part: discussions and conclusions (Chapter 6), where types of absorption chillers to be used are decided, economical and technological aspects of the two cooling production technologies are compared and it is reasoned out which the best solution is.

CHAPTER 2

Cooling system technologies

Production of cold is like considering extraction of heat. There are several procedures that allow it, which are based on the fact that the heat can be transferred from one to another body with a difference in temperature by conduction and radiation. In this way, there are several procedures: chemicals, physicals and systems that are based on phase transformation of substances. Likewise, refrigerating machines can be classified into: adsorption, absorption, compression and ejector machines. [3]

In industry, refrigerant compressor and absorption cooling systems are mostly used. Refrigerant cycles for vapour compression and absorption are similar in that both evaporate and condensate a refrigerant at different pressures to produce chilled water. Nevertheless, a vapour compressor chiller uses a mechanical means to compress and carry refrigerant vapour to condenser, whereas absorption chiller establishes differential pressure depending on a thermodynamic process that involves refrigerant and water. In addition, the energy source is electricity for compression chillers, while it is heat for absorption ones. It bears mentioning that there are also other heat-driven cooling alternatives, which are ejector, desiccant and hybrid heat-driven cooling technologies.

Next stage is to study both technologies.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

2.1. REFRIGERANT COMPRESSOR INSTALLATION

The most common cooling system used is refrigerant compressor technology, vapour compression heat pump to be precise. It is widely used for residential and commercial cooling, food refrigeration and automobile air conditioning. [4]

Vapour-compression system is a work-driven cycle that is illustrated in Figure 1. Main parts of the system are: condenser, evaporator, compressor and expansion valve. Depending on the system, it is possible to find more accessories, such as units to purge and valves for controlling the flow of refrigerant.

Figure 1. Refrigerant compression cycle [5]

The evaporator is a heat exchanger where refrigerant is evaporated at the expense of cooling space. It can be either an air coil, if air is directly cooled, or a chiller (shell heat exchanger) if it cools a liquid.

The compressor increases the pressure of refrigerant vapour, which is coming from the evaporator, in order to rise its temperature. The cooling capacity is regulated by varying the output of the compressor in most of the systems.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

The condenser is a heat exchanger where high-pressure refrigerant vapour, which is coming from the compressor, is cooled down until it is transformed into liquid. The cooling media can be air or water; larger systems use water since it allows reducing the condensing temperature, whereas small systems and those with limitation of water release directly heat to the air.

Some systems can have an accumulator, which depends on evaporator and condenser sizes and capacities, and pipes. It is actually a storage tank for liquid refrigerant.

In this way, how a vapour-compression cycle operates can be summed up (Figure 2.). First, input work in the compressor rises the pressure and temperature of the refrigerant (State 2). Then, refrigerant vapour with high pressure and temperature passes through the condenser, where it is converted into liquid by rejecting heat to ambient air (State 3). After that, refrigerant passes through an expansion valve where its temperature and pressure is reduced (State 4). Finally, low-pressure liquid refrigerant is transformed into low pressure vapour in the evaporator by absorbing heat from ambient environment (State 1). The cycle is completed when low pressure refrigerant enters the compressor. [5]

Figure 2. Temperature-Entropy (T-s) diagram for a Vapour-Compression Refrigeration Cycle (Source: http://www.qrg.northwestern.edu/thermo/design-library/refrig/refrig.html)

Chapter 2. COOLING SYSTEM TECHNOLOGIES

It is common a temperature lift of up to 50°C between evaporator and condenser and if water cooled chillers are used, a coefficient of performance (COP)1 of 4,5 can be reached.

Nowadays, the most usual refrigerants are ammonia (NH3) and R134A

(CHF2CHF2).

2.1.1. COMPRESSOR AND SYSTEM EFFICIENCY

The system efficiency analysis requires compressor design and compression process characteristics study [4]: a. Selection of refrigerant

The potential system efficiency depends on refrigerant used.

Regarding compressors, centrifuging compressors work well at low pressures and high specific volumes whereas alternative compressors work better at high pressures and small specific volumes.

Likewise, refrigerant’s temperature in the condenser and evaporator depends on cold and warm areas, which also define pressure regions. According to the previous description, high pressure is needed in the evaporator and low in the condenser.

1 The coefficient of performance for compression refrigerant systems is: COPcooling = ∆Qcold /∆W where ∆Qcold is the heat moved from the cold reservoir (to the hot reservoir) and ∆W is the work consumed by the system.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

Thus, refrigerant has to be selected taking into account required saturation pressure and temperature for each particular application. Moreover, it is necessary to consider chemical stability, toxicity, how corrosive it is and cost.

b. Flow in the compressor

The kinetic energy of the flow is influenced by its turbulence, which entails its conversion in waste heat energy. But leakages are the main problem of the compressor.

c. Primary energy: compressor driver

All energy input in a compression system goes into the compressor driver, which can be an electric motor (mostly), a reciprocating engine, a gas turbine or another machine.

2.2. ABSORPTION COOLING INSTALLATIONS

Absorption cooling cycle is similar to compression cycle, which uses a volatile refrigerant. Refrigerant vaporizes alternately under low pressure in the evaporator, by absorbing cooling latent heat from materia to be cooled, and condenses at high pressure, delivering latent heat into condensing means.

The main difference between absorption and compression cycles is, as shortly mentioned before, the motivating force that makes refrigerant to flow through the system and provides the differential pressure required between evaporating and condensing processes. In the absorption cycles, the compressor is replaced by an absorber and a generator (as it is shown schematically in Figure 3., components to the left of the dashed Z-Z line are the same as the ones used in compression cycles). Moreover, while energy required in compression cycles is

Chapter 2. COOLING SYSTEM TECHNOLOGIES

provided by compressor’s mechanical work, energy input in absorption cycles is in the form of heat supplied directly to the generator, which is typically steam or hot water.

Figure 3. Scheme of basic absorption cycle [5]

The system consists of four basic components: evaporator and absorber, which are located on the low pressure side of the system, and generator and condenser, which are located on the high pressure side. Two fluids are used, refrigerant and absorbent. The flow of refrigerant follows the cycle condenser- evaporator-absorber-generator-condenser, while absorbent goes from the absorber to the generator and returns to the absorber.

The sequence of operation is as follows: high pressure liquid refrigerant leaving the condenser passes through an expansion or restrictor device which reduces the pressure of refrigerant before it goes into the low pressure evaporator. Refrigerant vaporizes in the evaporator by means of absorbing latent heat of the material being cooled and low pressure refrigerant vapour is absorbed through a not restricted conduit to the absorber, where it is mixed in a solution together with the absorbernt.

Refrigerant flows from the evaporator to the absorber because vapour pressure of solution absorbent-refrigerant is lower in the absorber than vapour

Chapter 2. COOLING SYSTEM TECHNOLOGIES

pressure of refrigerant in the evaporator. Vapour pressure of solution absorbent- refrigerant in the absorber determines the pressure in low-pressure side of the system and accordingly, refrigerant´s evaporating temperature. In turn, vapour pressure of solution absorbent-refrigerant depends on absorber’s nature, temperature and concentration. The lower the temperature of absorbent is and, in addition, the higher its concentration is, the pressure in the solution will be lower.

As refrigerant vapour from the evaporator is dissolved in absorbing solution, volume of refrigerant decreases (compression) and heat is released. To keep the temperature and vapour pressure at the required level in absorbent solution, heat released in the absorber (which sums up latent heat of condensation of refrigerant vapour and heat from the absorption) should be given off to surroundings. Since the efficiency of absorber increases as the temperature of absorbent solution decreases, it is clear that the efficiency of the absorber depends on the temperature of refrigerant available.

When refrigerant vapour is dissolving in absorbing solution, resistance (percentage of refrigeration) and vapour pressure of the solution is increasing. Therefore, it is necessary to make continuously more concentrate the solution in order to keep the vapour pressure of it low enough, just as it is required in the evaporator. This is got by eliminating constantly the ―strong‖ absorbing solution from the absorber and flowing again through the generator, where it is evaporated by means of a heat source. In this way, the ―weak‖ absorbing solution is returned to the absorber, where it absorbs more refrigerant vapour from the evaporator.

According to all this, since the absorber is in the low pressure side of the system and the generator in the high pressure one, the ―strong‖ solution must be pumped from the absorber to the generator and the ―weak‖ solution must be returned through a pressure reducing valve or restrictor to the absorber. Refrigerant is not compressed in the process of increasing its pressure, since it has to take place in the absorber. Consequently, power required by the pump is relatively small.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

In the generator, solution is heated up and refrigerant is evaporated; like that, it is separated from absorbent. Afterward, obtained high pressure refrigerant vapour passes to the condenser, where its latent heat goes outside and it is condensed. Finally, it is ready for starting again the cycle.

With regard to the ―weak‖ solution that remains in the generator, as before described, it is returned to the absorber through the return pipe. Relative resistance on the ―weak‖ solution is controlled by the amount of heat supplied to generator. [4], [6], [7]

Once how the system works is known, it has to be underlined that maximum efficiency in the system is attained when pressure difference between low and high pressure sides in the system is as small as possible (by maintaining pressure in its low side as high as possible and as low as possible in the high pressure side). It should be remembered that the pressure in the low pressure side is mainly determined by absorbing solution’s vapour pressure, which in turn depends on the temperature and concentration of the solution. Since control of temperature in the solution is limited by available temperature of refrigerant, control in the low pressure side (evaporator) is usually obtained by means of varying concentration of absorbing solution.

The next stage is to study whether efficiency can be improved even more. This can be achieved by introducing a heat exchanger between the ―strong‖ solution that goes to the generator and the ―weak‖ solution (with high temperature) that returns from the generator to the absorber. As temperature of the solution that goes to the generator is increased, whereas it is decreased in that which goes to the absorber, it is needed to supply the generator with less heat as well as to cool down less in the absorber. [7]

From Figure 4. in the next page it can be seen an illustration of the described absorption system, where streams 11-12 represent heat source (steam or hot water), streams 15-16 cooling water, streams 17-18 district cooling water, streams 13-14 cooling water and so forth.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

Figure 4. Schematic of the fundamental absorption refrigeration system [8]

Furthermore, as well as in compression cycles, some gas is created in liquid refrigerant when it goes from the condenser to the evaporator, as a result of a pressure drop while it is passing through an expansion devise (valve). Consequently, effect of the refrigerant is reduced. Therefore, cooling effect and efficiency of the system would be improved if refrigerant that goes from the condenser to the evaporator was subcooled by means of introducing a heat exchanger between the evaporator and absorber.

2.2.1. CONSIDERATIONS FOR DIMENSIONING ABSORPTION CIRCUITS

It is more difficult to dimension absorption systems than compression ones. That is due to the fact that they work according to the thermodynamic balance, which changes depending on environmental conditions. For this reason, to determine whether instantaneous performance of certain equipments is correct,

Chapter 2. COOLING SYSTEM TECHNOLOGIES

it is necessary to measure periodically purity of water and saline solutions. With this purpose, there are used instruments, such as decanting pumps, and chemical additives are added.

Moreover, the efficiency depends on the quantity and quality of energy consumed in the generator. Hence, for those reasons, it is very important to obtain thermodynamic equilibrium (Qin = Qout → QE + QG = QC + QA).

2.2.2. WORKING FLUID

All absorption chillers just work as the presented basic cycle (Figure 3.), but their design and performance are based on the used working fluids (refrigerant and absorber). Likewise, their efficiency depends widely on (in addition to what has been explained before) properties of the working fluid.

Desirable properties are [9]:

Large affinity between absorbent and refrigerant.

Low heat of mixing.

An absorbent with very low volatility (refrigerant vapour that goes to the generator should contain few or nothing of absorbent).

Low pressures, close to the atmospheric pressure, to minimize leakages.

High latent heat of refrigerant, for minimizing flow rate.

The most conventional medias (refrigerant/absorbent) are water/lithium bromide and ammonia/water. Absorption chillers working with the first ones use water as refrigerant and lithium bromide as absorbent, whereas ammonia is the refrigerant and water the absorbent in the second combination.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

2.2.2.1. WATER/ LITHIUM BROMIDE (H2O/LiBr)

Lithium bromide as absorbent has the advantage of not being volatile (it is an hygroscopic salt), so it is not needed to purify desorbed water vapour. Nevertheless, it can crystallize easily.

The use of water as refrigerant is restricted by its freezing point. Hence, it must be used above 0 ºC but it may be achieved up to 5ºC.

Water/lithium bromide systems are typically used for production of chilled water for air conditioning systems in large buildings. Available sizes of these machines range from 10 to 1500 tons and their COP2 is between 0,7 and 1,2 [5].

2.2.2.2. AMMONIA/WATER (NH3/H2O)

High volatility of water makes to be necessary the introduction of a rectifier (reflux condenser) after the generator so that water steam that refrigerant contains is eliminated before it goes into the condenser. Otherwise, temperature in the evaporator is increased and consequently, cooling capacity decreases. Moreover, it may form ice in the evaporator and expansion device.

2 The coefficient of performance for absorption cooling systems is defined as: COPcooling = ∆Qcold /Qh where ∆Qcold is the heat moved from the cold reservoir (to the hot reservoir), that is, the refrigeration capacity, and Qh the heating energy.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

Figure 5. Ammonia/Water absorption cycle [5]

The mixture ammonia/water requires higher pressure and larger temperature differences: the driving temperature is usually 140 ºC.

With regards to the temperature of refrigerant, it is allowed to use much lower temperatures, around -60 ºC (the freezing temperature of ammonia is -77,7 ºC).

Concentration of ammonia has to be controlled as the mixture could become explosive if there is 15,5-27% of ammonia by volume (although ammonia/air mixtures are barely inflammable). [10]

Ammonia/water systems are more common for small tonnages, from 3 to 25 tons, and have generally COPs of around 0,5. This way, they are usually used in air conditioning systems. [5]

The use of ammonia as refrigerant has a large disadvantage. Toxicity of ammonia3 makes its use not possible in no well-ventilated areas. There might not

3 Ammnois is caustic, has a pungent smell and is toxic.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

be problems in an industry (since emissions from ammonia/water chillers could be solved in water and, as a result, a caustic solution would be formed), but they can be harmful to occupants in commercial and residential buildings. [11]

2.2.2.3. COMPARISON BETWEEN WATER/LITHIUM BROMIDE AND AMMONIA/WATER SOLUTIONS

Water/lithium bromide solution has two problems mainly: it exists the possibility of solid formation and the absorbent (LiBr) crystallizes at moderate concentrations. Then, this mixture can be normally used only when the absorber is water cooled, which temperature is kept by means of reconcentrating and controlling the absorbent solution. [12]

Figure 6. Crystallization temperatures of water/lithium bromide solution against the mass concentration of lithium bromide [12]

Thereby, temperature difference between evaporator and absorber cannot be higher than 40°C in order to avoid risk for crystallization. If higher temperature lifts are required, it is needed either to change chiller configuration or to use another working pair with higher hygroscopic temperature lift. [13]

Other disadvantages regarding water/lithium bromide pair are the low pressure (see Figure 7. and Figure 8.) that is required (improperly operated or

Chapter 2. COOLING SYSTEM TECHNOLOGIES

maintained units can lead to leak of atmospheric air into them) and the high viscosity of the solution. On the contrary, it is very safe and has high volatility ratio, affinity and stability, in addition to high latent heat. [12]

Figure 7. Maximum system pressures against the condenser temperature [12]

Figure 8. Minimum system pressures against the evaporator temperature [12]

As it can be observed from previous Figure 7. and Figure 8., operation pressures of the ammonia/water system are higher than water/lithium bromide ones.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

An evaporator temperature of around 3-4°C is normal for water/lithium bromide systems if the lowest temperature in the cooling net is 6°C [13]. A temperature of 30°C in the absorber and condenser would be reasonable for applications with low temperature cooling water (temperature in the condenser will set pressure in the generator) [13].

Ammonia/water systems are more complex than the water/lithium bromide ones (rectifier and so) and their performance depend on design parameters (it is required higher pressure and larger temperature differences). For this reason, construction of plants using ammonia is more expensive. Moreover, better heat recovery means is required [12].

Next Table 2. sums up properties of both solutions.

Table 2. Absorption working fluids´ properties [14] WATER/LITHIUM PROPERTY AMMONIA/WATER BROMIDE High latent Good Excellent

heat NT Modearate Too high Too low vapor pressure Low freezing Excellent Limited application

temperature REFRIGERA Low viscosity Good Good

Low vapour Poor Excellent pressure Low Good Good

ABSORBENT viscosity No solid fase Excellent Limited application Low toxicity Poor Good High affinity between Good Good

MIXTURE refrigerant and absorbent

Chapter 2. COOLING SYSTEM TECHNOLOGIES

In this way, let´s say that water/lithium bromide systems have much less problems and are simple to operate, although concentration of the mixture has to be controlled to prevent crystallization. Likewise, its COP (also limited by crystalization) is higher.

Figure 9. COP of the absorption systems against the condenser temperature (heat exchanger efficiency 0,6) [12]

Figure 10. COP of the absorption systems against the generator temperature (heat exchanger efficiency 0,6) [12]

Chapter 2. COOLING SYSTEM TECHNOLOGIES

Figure 11. COP of the absorption systems against the evaporator temperature (heat exchanger efficiency 0,6) [12]

Even though absorption cycles are mostly based on water/lithium bromide solutions (ammonia/water systems are unusual in the market), there are a lot of applications where ammonia/water can be used and especially where lower temperatures are needed. Main industrial applications for refrigeration are in the temperature range below 0ºC, which is the field for the binary system ammonia/water [11]. Hence, absorption systems using water as refrigerant are commonly used for air conditioning, whereas ammonia is used in large-tonnage industrial applications (such as food industry and slaughter houses) [12]. Consecuently, calculations of this thesis are based on water/lithium bromide systems.

2.2.3. PRIMARY ENERGY

There are two parts that need energy supply in absorption cycles: the generator and pump, which need heat and electricity respectively.

The required electricity represents 1-2% of the total cooling effect. With regards to the heat, depending on how absorption chillers are fired, the system can be:

Chapter 2. COOLING SYSTEM TECHNOLOGIES

Direct-fired system. Gas or another type of fuel is burned in the system. This system is used in residential applications to produce chilled water at 6ºC. In addition, it can supply hot water if an auxiliary heat exchanger is introduced.

Indirect-fired system. Fuel is steam or high temperature water that comes from a separate source such as CHP plants, geothermal, solar or waste heat. This thesis studies these ones.

Finally, it cannot be left behind that the absorber as well as condenser are cooled down by a refrigeration tower, which energy consumption has to be considered. Natural water, such as water from the river, can be used instead of cooling towers for optimizing overall efficiency of the system.

2.2.4. TYPES OF ABSORPTION CHILLERS

Although simple or single-effect absorption cycles (see Figure 5.) have just been studied, there are more types of absorption equipments in the market. The most common are single-effect (water/lithium bromide or ammonia/water) and double-effect (water/lithium bromide) chillers. Nevertheless, there are advanced H2O/LiBr cycles, such as low-temperature or half-effect chillers and triple-effect absorption chillers (the latest ones are in development), as well as two stage ammonia/water systems. Moreover, energy storage is possible in water/lithium bromide systems in the form of chemical potential difference [14].

The main difference between single- and double-effect absorption chillers is that the last ones uses two stages of lithium bromide solution reconcentration, which increases efficiency and reduces therefore energy consumption.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

2.2.4.1. SINGLE-EFFECT ABSORPTION CHILLERS

Single-effect absorption chillers use low-presure steam or hot water as energy source. The typical temperature range is from 93 to 132 °C. [5]

The COP for these chillers is, depending on the model, around 0,7 [13] (for instance, Carrier 16TJ-41 and 16TJ-42 have a COP of 0,73 and 0,72 respectively).

Figure 12. Cooling cycle schematic (Source: Carrier-Sanyo)

Chapter 2. COOLING SYSTEM TECHNOLOGIES

2.2.4.2. DOUBLE-EFFECT ABSORPTION CHILLERS

Because of the relative low COP associated with single-effect machines, it is difficult for them to compete economically with conventional vapour compression systems except for low waste heat applications where the input energy is free [14]. Double-effect technology, which purpose is to increase COP of the cycle, is much more competitive.

Double-effect absorption chillers, which are also known as super absorbers, use a second generator, condenser and heat exchanger that operate at higher temperature. Likewise, they require higher driving heat temperature and use steam.

Figure 13. Double-Effect Water/Lithium Bromide Absorption Chiller Schematic [5]

Schematic of double-effect machine provided as Figure 13. shows that the cycle includes two solution heat exchangers, which represents that internal heat exchange is achieved in practice by means of incorporating these two components into a single transfer device [14]. Low pressure condenser and generator operate

Chapter 2. COOLING SYSTEM TECHNOLOGIES

at approximately the same conditions as the ones of a single-effect mahine [14]. Operating temperature and pressure of high pressure devices can be inferred from Figure 14., which represents pressure-temperature chart schematic of double- effect water/lithium bromide chiller.

Figure 14. Sketch for a double effect absorption heat pump in a log pressure-temperature diagram [13]

The COP of two stages cycles is in the range of 1,0 to 1,2 [14] (for instance, Carrier 16NK-53 has a COP of 1,42).

Design for a double-effect absorption chiller is more complex compared to a single-effect chiller. How to connect solution circuits is one of the major design choices: parallel or series flow are the basic options [14]. A summary of performance of different types of double-effect technology configurations is presented in Table 3. (results are based on the same heat exchanger sizes and external fluid loop conditions).

Table 3. Comparison of parallel and series flow for double-effect water/lithium bromide cycles [14] CONFIGURATION COP CAPACITY [KW] Parallel 1,325 354,4 Serie, high-pressure generator first 1,244 371,1 Serie, low-pressure generator first 1,238 370,2

Chapter 2. COOLING SYSTEM TECHNOLOGIES

As it can be seen from Table 3. in the previous page, parallel flow configuration is the best option according to the COP. Nevertheless, capacity favors series flow configurations.

Even though a double-effect system needs more devices than a single- effect one, if a cooling tower is needed as a heat sink, less cooling tower capacity is needed per unit cooling effect due to the higher COP in a double-effect chiller [13]. Taking this into account, total system cost may be comparable to a single- effect chiller [13].

2.3. REFRIGERANT COMPRESSOR TECHNOLOGY VERSUS ABSORPTION COOLING TECHNOLOGY

As it has already been said, absorption cycles have some common characteristics with vapour compression cycles, but they differ in two important aspects:

1. Constitution of the compression process. In absorption cooling system vapour is not compressed between the evaporator and condenser, but refrigerant is absorbed by a secondary substance (absorbent) in order to form a liquid solution that is compressed to high pressure.

As the average specific volume of liquid solution is much lower than the average specific volume of refrigerant vapour, less work is needed. So absorption cooling systems have the advantage of, compared to vapour compression systems, requiring less power for compression.

2. In absorption systems a means should be introduced to recover the coolant steam from liquid solution before refrigerant enters the condenser, where it

Chapter 2. COOLING SYSTEM TECHNOLOGIES

is transferred heat from a source at a relatively high temperature. This makes economic residual heat and steam that otherwise would be thrown away untapped in environment.

Therefore, application of absorption equipments is a really interesting alternative for decreasing electricity consumption. Furthermore, companies which use steam in their processes have an additional advantage, since they would be using waste or residual steam.

Heat demand in absorption systems is higher than in compression ones. Actually, it can be, depending on evaporation temperature, more than three times higher; nevertheless, it has to bear in mind that waste heat is often used as driving heat. With regards to energy demand, following diagrams (Figure 15.), which show ratios between driving energy and produced refrigeration capacity, can be studied for making a comparison.

Figure 15. Comparison between compression and absorption technologies using ammonia as refrigerant and cooling water with a temperature of 25 ºC [10]

Chapter 2. COOLING SYSTEM TECHNOLOGIES

As it can be observed from the diagrams (Figure 15.), COP for absorption technology is much less affected by a drop in evaporating temperature. This is a significant advantage in overall economy. [11]

Initial costs for an absorption system are higher than for a compressor one of the same cooling capacity as:

Absorption system needs more metallic materials in heat exchangers.

Lower pressures are requiered in absorption technologies, which implies higher diameter of tubes in order to reduce pressure losses.

Size of condenser water pump is generally a function of flow rate per unit cooling capacity. Cooling technologies with lower COP typically require a significantly higher condenser water flow rate and, consequently, a larger pump too, than those technologies with higher COP. Similarly, absorption chillers require larger cooling tower capacity than electric chillers because of larger volume of water.

It is needed more space for absorption systems since the equipments are bigger. In addition, cost and volume of absorption machines increase when temperature of the generator is low.

A compression cooling machine needs roughly 0,5 kWh of electricity for providing 1 kWh cooling, whereas in an absorption process 1-1,2 kWh of heat is needed for that [15]. Regarding energy costs, it works out cheaper and more efficient to supply energy directly in form of heat than when it must go through several stages of transformation. Undoubtedly, economical advantages of absorption systems depend on how the driving heat is produced: it is generally not economic when a boiler has to be installed to generate cooling, but it is an interesting technology when waste heat or renewable energies with low price are used, as well as when capacity of the boiler is available all the time.

If investment and running costs are taken into consideration, absorption systems can compete against compression systems when the price of electricity is

Chapter 2. COOLING SYSTEM TECHNOLOGIES

from 8 to 9 times higher than the cost of heat. In CHP plants, high investment cost of absorption machines are thwart by the more efficient use of fuel (see Table 4.).

Table 4. Energy saving with cogeneration for α 4 = 0,54 SEPARATE SEPARATE TOTAL FUEL CHP ELECTRICITY HEAT production production CONSUMPTION (condensing plants) (steam boiler) FUEL 100 73,3 63,6 136,9 CONSUMPTION EFFICIENCY 0,88 0,42 0,9 ELECTRICITY 30,8 30,8 ― PRODUCTIOIN HEAT 57,2 ― 57,2 PRODUCTION

During warm periods, heat in excess in CHP plants decreases electricity production, since those plants are dimensioned for the heating demand in winter and hot water is only needed in summer. On the contrary, cooling demand increases in summer, so it takes the advantage of using the excess of heat for cooling systems.

Finally, operation and maintenance can be mentioned. The most important part in compression systems is compressor´s work, whereas it is the equilibrium obtained by thermodynamic effects in absorption systems. For this reason, operating with absorption technologies is more complicated (see Section 2.2.1.).

In this way, to sum up, absorption refrigeration systems´ operating characteristics can be listed [10]: - It is driven by ―economic‖ heat (waste or ―free‖ heat) and it has low consumption of electricity. - Simple design and maintenance (no moving machinery). - Long service life. - It is reliabiled, then it is more available. - Environmentaly ―friendly‖ working media (in addition, it is easy to clean effluent gases) and oil-free refrigerant. It is very clean and heat

4 Electric-thermal ratio: α = Wel/Qheat = ηel/ηt where Wel is the electrical power output, Qheat is the useful thermal power output, ηel is the electrical efficiency and ηt is the thermal efficiency.

Chapter 2. COOLING SYSTEM TECHNOLOGIES

transfer resistances due to contamination are not produced. In addition, carbon dioxide emissions are reduced at the same time. - Low noise level and there is no vibrations. The earliest three characteristics are the most important criteria when comparing absorption systems with vapour compression systems.

To finish with cooling technologies, Table 5. summarizes their characteristics and Table 6. makes a short comparison between them.

Table 5. Summary of characteristics for cooling options [13] DRIVING HEAT COP SCALE 5 TECHNOLOGY COPel TEMPERATURE (cooling) [kWcooling] [°C] Conventional (Single-effect) 0,7 20-50 120 >250 H2O/LiBr absorption chiller Double-effect 1,2 15-40 150-170 >350 H2O/LiBr absorption chiller

NH3/H2O absorption chiller 0,5 10-25 >100 ― Vapour compression chiller ― 1-5 ― ―

Table 6. Comparison between two 1000kW chillers [10]

5 It only includes the chiller electricity consumption for absorption systems

CHAPTER 3

District Cooling System

Distrist cooling system or technology delivers coolant, commonly chilled water, from a central refrigeration plant to multiple buildings through a distribution network. At each connection point of the distribution mains, energy is delivered to the terminal devices at the user premises to meet their space/process cooling requirements [1].

District cooling system is mainly made up of three components: cooling production plant, distribution network and building substations.

Figure 16. Components of district cooling systems

Figure 17. District cooling system (or district heating system6) [15]

6 The same concept applies when it comes to district heating systems.

Chapter 3. DISTRICT COOLING SYSTEM

District energy systems enable to use energy in a more efficient way and reduce greenhouse gas emissions because, on the one hand, it is used a central refrigeration plant instead of many small machines which are less efficient and, on the other hand, it is produced electricity for the central grid that can replace other electricity sources such as coal-fired plants.

3.1. PRODUCTION

3.1.1. COGENERATION. BENEFITS WITH INTEGRATION OF COOLING TECHNOLOGY

Cogeneration (combined heat and power, CHP) is the use of a power station for simultaneous generation of both electricity and useful heat (conventional power plants produce but not use a large amount of heat). That is, it is an energy conversion technology where two separate systems are integrated together by a cascade of thermal energy [14]. Thus, it can be led to increase the system performance7 by designing systems that can use the heat: the efficiency of energy production can be increased from current levels that range from 35% to 55%, to over 80% [16]. In addition, some of the obligatory heat rejection is at a high enough temperature to supply energy for comfort heating and cooling.

Figure 18. An schematic of cogeneration process that shows the consumed and produced power in the whole system [15]

7 Overall efficiency: ηtot = ηel + ηt = We/Qfuel + Qheat /Qfuel = (Wel + Qheat)/Qfuel It is also called energy utilization factor, EUF.

Chapter 3. DISTRICT COOLING SYSTEM

Figure 19. Illustration of a CHP plant connected to a district heating network (Source: Gävle Energi AB)

This way, shopping malls and blocks of business, university and collages, hospitals, industries and so forth take the advantage of the economic benefits provided by a central plant, through the use of boilers that produce hot water or steam for heating and vapour compression or steam-driven absorption refrigeration machines that produce chilled water for cooling.

Table 7. Different types of plants using a steam boiler and their characteristics HEATING CONDENSING Flexible, low operating and investment costs BOILER No full use of all heat in the fuel CHP plant Heat and electricity production (BIOFUELED STEAM BOILER) Full use of heat in the fuel Heat, electricity and cooling production TRIGENERATION plant Energy Export → CO2-negative (BIOFUELED STEAM BOILER) "Free" energy

There is only one requirement for the integration of two technologies: temperature of available heat from one system must be adequate to fulfil requirements of the mating system. The source of energy for district energy systems is usually a steam boiler, which is fired, in the cases to be considering in this thesis, by biofuel.

Chapter 3. DISTRICT COOLING SYSTEM

3.2. COOLING DISTRIBUTION SYSTEM

3.2.1. PIPING NETWORK

Flow in cooling (as well as in heating) distribution systems varies with the load, so the flow through each substation is regulated by two-way control valves. The reasons for this are mainly to lower pumping costs and to increase the difference between supply and return temperatures, which affects the efficiency of the whole system [15]: a higher supply and return temperature differential is able to lower the distribution pump power consumption, but will increase the heat loss at pipe surfaces [17]. Consequently, a high return temperature is preferable in district cooling system. This way, forward temperature is roughly 6 °C and return temperature is alternatively between 12 and 16 °C.

Anyway, distribution losses can be almost always neglected in district cooling systems since temperature difference between outdoor and forward water is very low and the resistances are therefore despised. For this reason, there is not needed, unlike in district heating, to insulate the pipes. This makes cooling distribution systems cheaper than heating ones.

Control valves must regulate the flow, but the pressure too. The available differential pressure becomes lower at substations which are furthest away in the system (because of greater pressure drops caused by the increased flow in the distribution system) and it might not be enough for the required flow. Hence, either another pump has to be used or the speed of the existing one has to be increased to maintain the differential pressure. [15]

Chapter 3. DISTRICT COOLING SYSTEM

3.2.2. MATERIALS FOR THE PIPES

There are different types of pipes depending on the application (pressure, gravity, drainage and so on). In this case, pressure pipe systems are studied.

There are polyethylene (PE), polypropylene (PP), PVC and PEX pipes, in addition to steel and cooper ones. For water applications, PE pipes are widely used because their quality is high and they are economic at the same time. This way, polyethylene pressure pipes offer the following benefits: - Cost saving with faster installation - Long life time and maintenance free - Suitability for renovation - Corrosion resistance - Flexibility (it allows ground movement) - Joint thightness

Plastic pipes are much cheaper than, for instance, steel ones. As the last ones are widely used in district heating systems, let´s say that the material for cooling pipes is less costly. Likewise, construction of networks works out cheaper than as appropiate for district heating pipes.

CHAPTER 4

Process

4.1. GATHERING OF INFORMATION ABOUT EXISTING INSTALLATIONS AND PRESENT SITUATION

4.1.1. STEAM BOILERS AT LEAF AND KAPPA

There is an oil steam boiler at LEAF8 nowadays, which has a maximum capacity of 5 MW and produces satured vapour at 8 bar. The average power it operates is 2 MW all over the year except for 48 h at Easter.

In addition, there is Kappa paper mill close to that boiler, which has another oil boiler of 2 MW and produces steam at 12 bar for 80 hours per week9.

In this way, Bionär10 is thinking about building a new biofueled steam boiler which would replace those two11. It is wanted to make the most of that and it is therefore planning to produce electricity too. Ramboll consultancy has considered building a biomass fired CHP plant based on Organic Rankine Cycle (ORC), as a low capacity boiler to produce needed steam at roughly 70 bar (which requires a sophisticate water purification system) and a turbine are much more expensive.

8 It is a factory which is located in Gävle and produces confectionery, candy and pastilles. 9 It is working 5 days/week, not at weekends, and 16h/day, not during night. 10 It is a subsidiary of Gävle Energy AB, which owns the 45%. One of the customers of Bionär is LEAF. 11 Although the operating times of the boilers are different, the new boiler can work at 2 MW during the day and increase its capacity during the night, when it can be produced the steam which is needed in the paper mill during the day (storage in accumulator vessels).

4. PROCESS

Figure 20. ORC plant in biomass based cogeneration system (Source: http://www.turboden.it/en/products.asp)

ORC units have high overall energy efficiency: 20% of the thermal power is transformed into electric power, while 78% remains as steam. Nowadays, it is planning to build a TURBODEN 14 CHP plant that costs 5 300 000 SEK and which performance is 1,26 MW of net active electric power and 5,35 MW of steam (α = 0,23), with a biomass consumption of 7,63 MW.

. Figure 21. Energy efficiency of ORC units in cogeneration applications (Source: http://www.turboden.it/en/products.asp)

Gävle Energi AB, as knows of this project, might take the opportunity to use this installation turning it into a trigeneration plant by means of introducing an absorption cooling system that would use the steam produced in it. Hence, it is needed an even bigger ORC unit and to make a decision about it is one of the tasks of this project.

4. PROCESS

4.1.2. BIOFUELED JOHANNES CHP PLANT

Johannes CHP plant (Figure 22.), which is owned by Gävle Kraftvärme AB12, is located in the south of Gävle, exactly in Johannesbergsvägen.

Figure 22. Johannes CHP plant before 2003 (Source: Gävle Energi AB)13

The steam boiler was built in 1999, which aim is to produce heat to deliver in the district heating network of the municipality. It is a Bubble Fluidized Bed (BFB) boiler and has a maximum capacity of 77 MW, whereas the minimum power output is 20 MW.

Johannes is not able to fulfil the heating demand of Gävle in winter, so waste heat is bought from Korsnäs pulp and paper mill in Gävle for distributing it in the system. In summer time, when the demand decreases noticeably (as it is only needed for hot water), the steam coming from Korsnäs is enough to meet customer requirements and therefore, the boiler at Johannes is shut down (in other periods, its power output is reduced). Last year (2008) the plant was operating 6500 hours continiously (24 h/day), which means that it was stopped roughly 95 days during summer.

In 2003 a backpressure turbine of 22 MW was introduced, turning this way the installation into a cogeneration plant. This enables to increase profits to great extends; actually, the company makes money from electricity, although its

12 It owns all production facilities in Gävle Energi AB but it is owned 100% by Gävle Energi AB. 13 The turbine is missing since it was introduced in 2003.

4. PROCESS

production has to be managed according to the heating demand of the municipality.

Taking into consideration average values, 320 GWh of steam are produced, which entails 406,4 GWh of biofuel consumption. With regards to electricity, the production is around 97 GWh (as α value is 0,29), which means a large profit.

Figure 23. Production of heat (for District Heating) and electricity at Johannes

The next challenge could be to introduce an absorption cooling plant and Johannes would have to do with a trigeneration, which would be able to fulfil the cooling demand in the shopping centers (Hemlingby) close to that by means of a distribution system. Furthermore, electrically driven refrigeration devices that are mainly used for the turbine could be replaced. And last but not least, the boiler could be kept running almost the whole year with a large income because of the electricity produced (there are possibilities to increase electricity output by increased heat load from heat-driven chillers, especially in June-August. See Figure 23.)

For more information about Johannes CHP plant, see Appendix 7.

4. PROCESS

4.1.3. MACKMYRA

Nowadays, Mackmyra Svensk Whisky is located in Valbo, at the outskirts of Gävle. There is an electric boiler with a capacity of 850 kW that operates continuously all over the year14, which is owned by Bionär.

Figure 24. Existing electric boiler in Mackmyra (Source: Gävle Energi AB)

According to an already approved project, a new plant, Mackmyra Whiskyby, will be probably built with a bigger production capacity. It is planned to be in Western Kungsbäck, just at the west of the central Gävle and few kilometers from the existing distillery, and it will be built in several stages, starting in the second half of this year (2009).

A bigger distillery entails, among other things, the necessity of a bigger boiler. Thus, it has been proposed to replace the electric boiler by a biofueled boiler with capacity doubled so that it could be turned into a cogeneration plant by introducing a turbine. This means that, in addition to produce steam needed in the factory, profits would be increased because of electricity output.

It could be even thought about a bigger boiler and a third step could take place. As well as for LEAF, Gävle Energi AB might turn it into a trigeneration plant where cold would be produced by firing absorption cooling machines with steam. It is estimated that it would be needed a ten times bigger boiler;

14 ≈ 8760 h/year. It is only switched off because of breakdowns and maintenance.

4. PROCESS

nonetheless, it will be calculated according to the cooling demand in that site of the victinity.

Figure 25. Existing and planned boilers at Mackmyra (different stages)

4.1.4. REFRIGERATION COMPRESSOR COOLING PROJECT

The refrigerant compressor cooling project, which plans to fulfil the cooling demand in the city center by producing chilled water at LEAF and delivering it by district system, is being built now and it is thought the first stage will be finished for next summer (2009). Nowadays, there is only one customer, which has a cooling demand of roughly 250 kW.

The drafts of installations and equipments needed are in Appendix 1. According to the calculations, that can be also seen in Appendix 1., the investment cost for the installation is 22 629 000 SEK, which has a pay-back time of approximately 10 years. There are needed roughly 4 240 675 kWh of electricity per year for running the whole installation, which means 4 240 675 SEK per year, and there are produced 7 142 836 kWh of cooling per year by means of compression technology. With regards to the maintenance costs, those are time dependant and 170 000 SEK for the first year (see Section A1.4. in Appendix 1.). This way, the total cost of the system for ten years is 66 204 500 SEK.

4. PROCESS

4.2. GATHERING OF DATA: CUSTOMERS. LOAD REQUIRED AND DISTANCES

Once different existing possibilities of building absorption cooling systems have been studied, two small islands with future large district cooling customers have been defined: Hemlingby shopping centers in Johannesbergsvägen and Kungsbäck area, which would comprise the university (Högskolan i Gävle), hospital (Gävle Sjukhus) and technological park (Teknikparken). This way, the production sites would be Johannes and planned new Mackmyra whisky factory.

Moreover, the city center is also subject of investigation, so that it is the third island, which cooling demand could be supplied by introducing absorption chillers at LEAF. Then, it will have to be studied if it is economic to replace the compression refrigeration plant.

4. PROCESS

Figure 26. Three cooling production and customer sites and main pipes

4. PROCESS

Next Table 8. shows different cooling demands for the planned three production sites (see Appendix 2.).

Table 8. Cooling load demand at each site COOLING PRODUCTION CUSTOMER DEMAND SITE/AREA [MW] LEAF 2,5 LEAF/CITY CENTER CITY CENTER 9,0 11,5 TOTAL MACKMYRA ± 0 HOSPITAL 1,7 MACKMYRA/

KUNGSBÄCK UNIVERSITY 1,8 TECHNOLOGIC PARK 1,0 5,0 TOTAL JOHANNES 1,4 HEMLINGBY SHOPPING JOHANNES/ 2,0 JOHANNESBERGSVÄGEN CENTERS 3,4 TOTAL

Regarding distribution systems, as it can be seen in Appendix 4., the main pipe in the city center is 1370 meters long. Far away from the city center, Johannesbergsvägen area is and, according to the estimations (see Appendix 4.), there are 1775 m between the plant and the buildings that need cooling. The third and last area is Kungsbäck, where it would be needed a pipe from Mackmyra to the hospital, 2390 m, and to the university too, 810 m; nonetheless, it could be used the same pipe for both of them in the first 500 meters (see Appendix 4.).

4. PROCESS

4.3. ANALYSIS OF ABSORPTION COOLING PLANTS

4.3.1. ABSORPTION CHILLERS

Next task is to study the absorption cooling machines to be used. There are mainly two options, starting with a premise that they have to be steam-fired: single- and double-effect steam-fired absorption chillers. The difference between them is that the double-effect has two generators, thus a better COP and higher cost, roughly from 2 to 2,5 times the price of the single-effect.

Single-effect absorption chillers are designed for using available low sature pressure waste steam (100-150 kPa), so they are a recovery solution. With regards to double-effect chillers, they use satured steam at around 500-800 kPa. In this context, as mentioned before (Section 2.2.2.3.), water/lithium bromide units are only considered

Following Table 9. and Table 10. gather information about different possible installations (calculations and specifications are in Appendix 3.). Even though chillers with highest cooling capacity have been considered, they cannot cover the cooling demand and therefore, it is necessary to add several units in parallel.

Table 9. Possibilities to fulfill the cooling demand in the city center by using steam-fired absorption chillers DOUBLE-EFFECT STEAM- SINGLE-EFFECT STEAM-

FIRED ABSORPTION FIRED ABSORPTION PRODUCTION SITE CHILLER: TSA-16NK- 81 CHILLER: TSA-16TJ- 53

NUMBER OF CHILLERS NUMBER OF CHILLERS LEAF 3 5

4. PROCESS

Table 10. Possibilities to fulfill the cooling demand in Kungsbäck by using steam-fired absorption chillers DOUBLE-EFFECT STEAM- SINGLE-EFFECT STEAM- FIRED ABSORPTION FIRED ABSORPTION PRODUCTION SITE CHILLER: TSA-16NK- 81 CHILLER: TSA-16TJ-53

NUMBER OF CHILLERS NUMBER OF CHILLERS MACKMYRA 2 2

At first, it was focused on steam-fired machines for being more efficient. Nonetheless, it has been deduced it is not possible their use at Johannes plant from the analysis of steam streams. During summer, when the boiler is at its minimum capacity nowadays, the pressure of the steam leaving the turbine is lower than 1 bar (see Table A3. 1.), which is the minimum pressure required for satured steam needed in single-effect steam-fired absorption chillers. It would be possible to use high-pressure super-heated steam that enters the turbine (see Figure A3. 1.); however, it is not an interesting alternative as electricity production would be therefore reduced (it would mean going down in profits). As a result, water/lithium bromide single-effect hot water-fired absorption chillers have been studied (Table 11.).

Table 11. Possibilities to fulfill the cooling demand corresponding to Johannes plant SINGLE-EFFECT HOT WATER-FIRED PRODUCTION ABSORPTION CHILLER: TSA-16LJ- 53 SITE

NUMBER OF CHILLERS

JOHANNES 2

4.3.1.1. STUDY OF OPERATIONAL CONDITIONS

Cooling demand changes during the year mainly because of climatic conditions (time period). Despite total or maximum cooling demand is only known, an estimation can be made for the whole year (see Section A3.3., Appendix 3.):

4. PROCESS

Table 12. Cooling that should be produced for different sites during the year COOLING TIME PERIOD POWER PRODUCTION [kW] LEAF MACKMYRA JOHANNES Winter time: 15 November-15 March 895 389 1556 15 March-1 April & 1-15 November 3512 1527 2011 April & 15 October-1 November 4683 2036 2214 1-15 May & 15 September-15 October 6749 2934 2574 15 May-15 June & 15 August-15 September 9779 4252 3101 Summer time: 15 June-15 August 11500 5000 3400

Figure 27. Cooling power to be produced in different sites during the year

In winter the cooling demand is very low. Hence, there is no need for producing cooling at LEAF (899 kW) and Mackmyra (389 kW) due to the fact that free cooling is allowed in this time of the year15. With regards to Johannes (1556 kW), there is no river around the plant, so it is necessary to fulfil the demand in another way. As heat demand is the highest in winter, produced hot water cannot be used for firing absorption chillers (all heat ought to be delivered in the district heating network) and consequently, the best solution would be to use the already existing cooling and HVAC systems in Hemlingby and Johannes during winter.

15 The river is far away from Mackmyra production site but the customers (university and hospital) are quite close to it. Therefore, it is possible to introduce heat exchangers there for free cooling in this area.

4. PROCESS

4.3.2. THE REST OF EQUIPMENTS

Figure 28. Typical piping diagram of an absorption system (Source: Carrier-Sanyo)

The operation of chillers needs additional devices and equipments: - Cooling towers. - Chilled water pumps and cooling water pumps for each chiller. - Strainier, pressure gauge and drain trap, which should be near the steam inlet, for each chiller. - Air vent valve in each of the chilled and cooling water lines. - Shut-off valve to prevent the steam flow into the chiller during shut-down. - Etc.

Necessary pumps, valves, pipes, etc. inside production installations cannot have been calculated because of limited provided information. Thus, same investment and operational costs (power input) as for absorption cooling project which has just been built in Falun (see Appendix 6.) have been considered.

Regarding cooling towers, they produce cold water for cooling down absorbers and condensers inside the chillers and their size is decided according to the required cooling power. This equipment can be replaced by a heat exchanger at LEAF, as water from the river is cold enough.

4. PROCESS

Lastly, there are two more heat exchangers which are planning to be used for free cooling at LEAF and Mackmyra in winter time.

Specifications about cooling equipments (cooling towers and heat exchangers) are gathered together in Table A3. 8. (Appendix 3.).

CHAPTER 5

_ Results

5.1. PRODUCTION PLANTS

5.1.1. LEAF

5.1.1.1. OPERATIONAL CONDITIONS

Table 13. Power and steam demand of different chillers sets for the required cooling load at LEAF during the year NUMBER OF POWER SUPPLY STEAM SUPPLY CHILLERS COOLING LOAD16 [MWh] TO CHILLERS TO CHILLERS TIME PERIOD WORKING [MWh] [MWh] FREE ABSORPTION 16NK-81 16TJ-53 16NK-81 16TJ-53 16NK-81 16TJ-53 COOLING COOLING 15 November-15 March — — 862,78 — — — — — 15 March-1 April & 1-15 November 1 2 — 856,93 2,62 1,72 750,96 1412,95 April & 15 October-1 November 1 2 — 1704,61 3,90 2,56 1483,92 2811,27 1-15 May & 15 September-15 October 2 3 — 2902,07 9,22 4,54 2543,56 4785,81 15 May-15 June & 15 August-15 September 3 4 — 6571,49 21,61 9,46 5759,41 10836,57 15 June-15 August 3 5 — 8487 23,73 12,99 7438,75 13993,87 TOTAL [MWh/year] 862,78 20 522,10 61,08 31,27 17 976,60 33 840,46

16 Operation hours data are taken from Anders Kedbrant estimations, Table A1. 15. (Appendix 1.), for all calculations because of lack of information.

5. RESULTS

Table 14. Biofuel (for producing steam), electricity and water consumption. LEAF 16NK-81 16TJ-53 TOTAL BIOFUEL CONSUMPTION17 [GWh/year] 25,71 48,39 CHILLERS 61,08 31,27 ELECTRIC POWER REST OF THE PLANT18 450,82 SUPPLY [MWh/year] TOTAL 511,91 482,10

5.1.1.2. COSTS

5.1.1.2.1. INVESTMENT COSTS Table 15. Investment costs [SEK] for LEAF 3 ABSORPTION CHILLERS 5 ABSORPTION CHILLERS TSA-16TJ- 53 3 * 6 200 000 5 * 2 700 000 TSA-16NK- 81 (CARRIER-SANYO) (CARRIER-SANYO) BACK-UP COMPRESSOR CHILLER 19 BACK-UP COMPRESSOR CHILLER 600 000 600 000 YRTBTBT0550C (YORK) YRTBTBT0550C (YORK) 3 HEAT EXCHANGERS S121-IS10-502-TMTL47-LIQUIDE (Sondex) 5 HEAT EXCHANGERS (+ FILTER) 3 * 619 000 5 * 550 000 + MX25-MFMS (Alfa Laval) FILTERS BSG350/1,0P (Bernoulli) HEAT EXCHANGER (+FILTER) HEAT EXCHANGER (+FILTER) 120 000 120 000 TL10-BFG TL10-BFG REST OF THE INSTALLATION20 1 450 000 REST OF THE INSTALLATION 1 450 000 TOTAL [SEK] 22 627 000 TOTAL [SEK] 18 420 000 NOTE: all specifications are in Appendix 3.

17 Biofuel consumption in the ORC CHP plant (TURBODEN 14) = 1,43 MW biofuel/MW steam 18 Reference: Falun Cooling Project (see Appendix 6.). Considered operation hours = chiller´s operation hours. It is known that submersible pumps for the whole installation are working the whole year but data about them is missing. It has been assumed the same for both Mackmyra and Johannes production plants. 19 The considered back-up chiller is the one planned for compression refrigeration project (VKA3). It is only considered its investment cost as it is not usually running (it is just started up because of breakdowns and when the cooling demand is higher than the expected one). Calculations for Mackmyra and Johannes production sites are also based on the same compressor. 20 Reference: Falun Cooling Project (see Appendix 6.). It has been assumed the same for both Mackmyra and Johannes production plants.

5. RESULTS

5.1.1.2.2. OPERATIONAL COSTS

Table 16. Operational costs at LEAF21 16NK-81 16TJ-53 BIOFUEL [SEK/year] 4 241 579,13 7 984 657,3 -165 SEK/MWh-22 ELECTRICITY [SEK/year] 511 906,24 482 095,36 - 1 SEK/kWh- TOTAL [SEK/year] 4 753 485,4 8 466 752,7

5.1.1.2.3. TOTAL COSTS

PAY-BACK time of the equipments (chillers, pumps, etc.) is roughly 10 years (the investment is recovered approximately after ten years). Thus, costs are calculated for this period of time:

Table 17. Total costs of LEAF absorption cooling plants for 10 years 16NK-81 16TJ-53 TOTAL INVESTMENT 22 627 000 18 420 000 70 164 854 103 087 527 COSTS [SEK] OPERATING 47 534 854 84 667 527 PROFITS: ELECTRICITY PRODUCTION [SEK] - 31 836 561 - 59 931 460 - 770 SEK/MWh-23 TOTAL [SEK] 38 328 293 43 156 067

Maintenance costs are very low because there are few components that demand maintenace and there is just cleaning work mainly. As a result, these costs can be neglected.

21 Operational costs of producing steam are not considered as explained in Chapter 1 (Limitations). 22 Biofuel price was 150 SEK/MWh in 2008. As it is rising all the time, it has been considered 10% more expensive for the future. 23 Electricity selling price to the grid was 700 SEK/MWh in 2008. As it is rising all the time, it has been estimated that profits are 10% larger in the future. Electricity selling price is made up of two major parts: actual electricity (MWh) delivered into the electrical grid (400 SEK/MWh) + green certificates, GCs (1 MWh = 1 certificate; 300 SEK/MWh).

5. RESULTS

Next graph, Figure 29., compares all costs for different chillers sets at LEAF.

Figure 29. Graph that shows the breakdown of total costs for 10 years at LEAF

After ten years, there are only operational costs, which are lower for 16NK-81 chillers set. If profits due to electricity production are taken into account, costs for fulfilling customer’s demand in the city center will be 1 569 829 SEK/year and 2 473 607 SEK/year for 16NK-81 and 16TJ-53 chillers set installations respectively.

5. RESULTS

5.1.2. MACKMYRA

5.1.2.1. OPERATIONAL CONDITIONS

Table 18. Power and steam demand of different chillers sets for the required cooling load in Mackmyra production during the year NUMBER OF POWER SUPPLY STEAM SUPPLY CHILLERS COOLING LOAD [MWh] TO CHILLERS TO CHILLERS TIME PERIOD WORKING [MWh] [MWh] FREE ABSORPTION 16NK-81 16TJ-53 16NK-81 16TJ-53 16NK-81 16TJ-53 COOLING COOLING 15 November-15 March — — 375 — — — — — 15 March-1 April & 1-15 November 1 1 — 372,59 2,62 0,86 326,51 614,35 April & 15 October-1 November 1 1 — 741,10 3,90 1,28 649,46 1221,98 1-15 May & 15 September-15 October 1 2 — 1261,62 4,61 3,03 1105,60 2080,23 15 May-15 June & 15 August-15 September 1 2 — 2857,34 7,20 4,73 2503,99 4711,36 15 June-15 August 2 2 — 3690 15,82 5,20 3233,68 5989,37 TOTAL [MWh/year] 375 8922,66 34,15 15,09 7819,23 14 617,29

Table 19. Biofuel (for producing steam), electricity and water consumption. Mackmyra 16NK-81 16TJ-53 TOTAL BIOFUEL CONSUMPTION24 [GWh/year] 11,18 20,90 CHILLERS 34,15 15,09 ELECTRIC POWER COOLING TOWERS (fans) 26,32 43,49 SUPPLY [MWh/year] REST OF THE PLANT 450,82 TOTAL 511,30 509,40 TOTAL WATER FOR COOLING TOWERS [m3/year] 37 147,6 34 148,2

24 It has been assumed that the biofuel consumption in the future boiler at Mackmyra is the same as in the one at LEAF, as the boiler might be small and its efficiency is not therefore very high.

5. RESULTS

5.1.2.2. COSTS

5.1.2.2.1. INVESTMENT COSTS

Table 20. Investment costs [SEK] for Mackmyra 2 ABSORPTION CHILLERS 2 ABSORPTION CHILLERS TSA-16TJ- 53 2 * 6 200 000 2 * 2 700 000 TSA-16NK- 81 (CARRIER-SANYO) (CARRIER-SANYO) BACK-UP COMPRESSOR CHILLER BACK-UP COMPRESSOR CHILLER 600 000 600 000 YRTBTBT0550C (YORK) YRTBTBT0550C (YORK) 2 COOLING TOWERS 2 COOLING TOWERS 2 * 1 595 000 2 * 998 000 OCT09HB05-5-90 (Vestas Aircoil) OCT09HB03-3-120 (Vestas Aircoil) HEAT EXCHANGER (+ FILTER) HEAT EXCHANGER (+ FILTER) 60 000 60 000 TL6-BFG TL6-BFG REST OF THE INSTALLATION 1 450 000 REST OF THE INSTALLATION 1 450 000 TOTAL [SEK] 17 700 000 TOTAL [SEK] 9 506 000

5.1.2.2.2. OPERATIONAL COSTS

Table 21. Operational costs in Mackmyra production site 16NK-81 16TJ-53 BIOFUEL [SEK/year] 1 844 948,48 3 448 948,8 -165 SEK/MWh- ELECTRICITY [SEK/year] 511 296,31 509 404,38 - 1 SEK/kWh- WATER [SEK/year] 148 590,4 136 592,8 - 4 SEK/m3- TOTAL [SEK/year] 2 504 835,19 4 094 945,98

5. RESULTS

5.1.2.2.3. TOTAL COSTS

Table 22. Total costs of Mackmyra absorption cooling plants for 10 years 16NK-81 16TJ-53 TOTAL INVESTMENT 17 700 000 9 506 000 42 748 352 50 455 460 COSTS [SEK] OPERATING 25 048 352 40 949 460 PROFITS: ELECTRICITY PRODUCTION [SEK] - 9 031 216 - 16 882 966 - 770 SEK/MWh-25 TOTAL [SEK] 33 717 136 33 572 494

Next graph, Figure 30., compares all costs for different chillers sets in Mackmyra production site.

Figure 30. Graph that shows the breakdown of total costs for 10 years in Mackmyra production site

After ten years, if profits due to electricity production are taken into account, costs for fulfilling customer’s demand in Kungsbäck area will be

25 Assumption: α = 0,15. It has to be quite smaller than for Johannes (α = 0,29) since the boiler is smaller and works at lower pressure. The smaller the boiler is, the lower the efficiency is. Moreover, the lower pressure in the boiler is, the lower electricity production is (α value depends mainly on the pressure of the boiler).

5. RESULTS

1 601 714 SEK/year and 2 406 649 SEK/year for 16NK-81 and 16TJ-53 chillers set installations respectively.

5.1.3. JOHANNES

5.1.3.1. OPERATIONAL CONDITIONS

Table 23. Power and hot water demand of chillers set for the required cooling load at Johannes during the year HOT POWER NUMBER OF ABSORPTION WATER SUPPLY TO TIME PERIOD 16LJ-53 COOLING SUPPLY TO CHILLERS CHILLERS LOAD [MWh] CHILLERS [MWh] WORKING [MWh] 15 November-15 March — — — — 15 March-1 April 2 490,68 1,72 733,84 1-15 November April 2 805,90 2,56 1204,65 15 October-1 November 1-15 May 2 1106,82 3,03 1654,47 15 September-15 October 15 May-15 June 2 2083,87 4,73 3115,98 15 August-15 September 15 June-15 August 2 2509,2 5,20 3750,75 TOTAL [MWh/year] 6996,47 17,23 10459,69

5.1.3.2. COSTS

Table 24. Biofuel (for producing steam), electricity and water consumption. Johannes

16LJ-53 TOTAL BIOFUEL CONSUMPTION26 [GWh/year] 13,28 CHILLERS 17,23 HVAC systems (winter time)27 749,99 ELECTRIC POWER COOLING TOWERS (fans) 36,50 SUPPLY [MWh/year] REST OF THE PLANT 450,82 TOTAL 1254,55 TOTAL WATER FOR COOLING TOWERS [m3/year] 28 753,8

26 Biofuel consumption in Johannes = 1,27 GWh biofuel/GWh steam 27 HVAC systems´cooling factor: COP =cooling/(electricity to compressor) = 2-3. As the systems are not new and operational conditions are unknown, COP = 2 has been considered.

5. RESULTS

5.1.3.2.1. INVESTMENT COSTS

Table 25. Investment costs [SEK] for Johannes 2 ABSORPTION CHILLERS 2 * 2 700 000 TSA-16LJ- 53 (CARRIER-SANYO) BACK-UP COMPRESSOR CHILLER 600 000 YRTBTBT0550C (YORK) 2 COOLING TOWERS 2 * 675 000 OCT09HB02-2-120 (Vestas Aircoil) REST OF THE INSTALLATION 1 450 000 TOTAL [SEK] 8 800 000

5.1.3.2.2. OPERATIONAL COSTS

Table 26. Operational costs in Johannes production site 16LJ-53 BIOFUEL [SEK/year] 2 191 828,57 -165 SEK/MWh- ELECTRICITY [SEK/year] 1 254 551,77 - 1 SEK/kWh- WATER [SEK/year] 115 015,2 - 4 SEK/m3- TOTAL [SEK/year] 3 561 395,54

5.1.3.2.3. TOTAL COSTS

Table 27. Total costs of Johannes absorption cooling plant for 10 years 16NK-81 TOTAL INVESTMENT 8 800 000 44 413 955 COSTS [SEK] OPERATING 35 613 955 PROFITS: ELECTRICITY PRODUCTION [SEK] - 23 356 493 - 770 SEK/MWh- TOTAL [SEK] 21 057 462

Next graph, Figure 31., shows all costs for 10 years in Johannes production site.

5. RESULTS

Figure 31. Graph that shows the breakdown of total costs for 10 years in Johannes production site

After ten years, if profits due to electricity production are taken into account, costs for fulfilling customer’s demand in Johannesbergsvägen area will be 1 225 746 SEK/year.

5. RESULTS

5.1.4. SENSITIVITY ANALYSIS

Apart from studying different production sites according to possible customers´ demand, a sensitivity analysis28, which ranges over size of absorption units and other equipments, costs and profits, has been carried out for when the cooling demand is both ten percent higher and lower than the estimated one.

5.1.4.1. LEAF

When cooling demand is 10% higher, one more 16 TJ-53 single-effect absorption chiller is needed at LEAF. Hence, one more MX25-MFMS (Alfa Laval) heat exchanger for cooling down single-effect chillers set (with six chillers in parallel) has to be introduced too. Furthermore, it cannot be left behind that cooling load is also higher in winter time (1012,7 kW).

Next Table 28. and Table 29. gather together new operational conditions and total costs respectively.

Table 28. Operational conditions of different chillers sets at LEAF during the year when the cooling demand is 10% higher than the estimated one TOTAL TOTAL TOTAL STEAM TOTAL BIOFUEL ELECTRICITY COOLING LOAD SUPPLY CONSUMPTION SUPPLY [MWh/year] [MWh/year] [MWh/year] [MWh/year] FREE ABSORP. 16NK-81 16TJ-53 16NK-81 16TJ-53 16NK-81 16TJ-53 COOL. COOL. 976,24 23 198,59 20 331,87 41 420,45 515,81 489,85 29 074,58 59 231,24

Table 29. Total costs of LEAF absorption cooling plants for 10 years when the cooling demand is 10% higher than the estimated one 16NK-81 16TJ-53 TOTAL INVESTMENT 22 627 000 21 670 000 75 758 141 124 300 077 COSTS [SEK] OPERATING 53 131 141 102 630 077 PROFITS: ELECTRICITY - 36 007 749 - 73 355 610 PRODUCTION [SEK] TOTAL [SEK] 39 750 391 50 944 467

28 Calculations in this Section 5.1.4. are based on the same assumptions and estimations as for the three cases studied before.

5. RESULTS

When cooling demand is 10% lower, chiller configurations do not change; either three 16NK-81 units or five 16TJ-53 units in parallel are still needed. In this case, 779 kW of free cooling are necessary.

Following Table 30. and Table 31. show, on the one hand, new total cooling load and operational conditions; on the other hand, the total costs (take note that investment costs are the same).

Table 30. Operational conditions of different chillers sets at LEAF during the year when the cooling demand is 10% lower than the estimated one TOTAL TOTAL TOTAL STEAM TOTAL BIOFUEL ELECTRICITY COOLING LOAD SUPPLY CONSUMPTION SUPPLY [MWh/year] [MWh/year] [MWh/year] [MWh/year] FREE ABSORP. 16NK-81 16TJ-53 16NK-81 16TJ-53 16NK-81 16TJ-53 COOL. COOL. 750,96 17 845,07 15 640,52 29 426,53 504,70 482,10 22 365,94 42 079,94

Table 31. Total costs of LEAF absorption cooling plants for 10 years when the cooling demand is 10% lower than the estimated one 16NK-81 16TJ-53 TOTAL INVESTMENT 22 627 000 18 420 000 64 577 824 92 672 852 COSTS [SEK] OPERATING 41 950 824 74 252 852 PROFITS: ELECTRICITY - 27 699 356 - 52 114 385 PRODUCTION [SEK] TOTAL [SEK] 36 878 468 40 558 467

5. RESULTS

5.1.4.2. MACKMYRA

When cooling demand is 10% higher, one more 16 TJ-53 single-effect absorption chiller is also required in Mackmyra production site. This way, one more OCT09HB03-3-120 (Vestas Aircoil) cooling tower is needed too. Likewise, roughly 39 kW cooling/year more ought to be produced by means of free cooling in winter.

New total cooling load and operational conditions as well as total costs are shown in Table 32. and Table 33.

Table 32. Operational conditions of different chillers sets in Mackmyra production site during the year when the cooling demand is 10% higher than the estimated one TOTAL TOTAL STEAM TOTAL BIOFUEL TOTAL WATER TOTAL COOLING ELECTRICITY SUPPLY CONSUMPTION CONSUMPTION LOAD [MWh/year] SUPPLY [MWh/year] [MWh/year] [m3/year] [MWh/year]

FREE ABSORP. 16NK-81 16TJ-53 16NK-81 16TJ-53 16NK-81 16TJ-53 16NK-81 16TJ-53 COOL. COOL.

413,03 9 814,79 8 600,87 16 181,66 512,05 510,02 12 299,24 23 139,78 44 472,4 40 396,1

Table 33. Total costs of Mackmyra absorption cooling plants for 10 years when the cooling demand is 10% higher than the estimated one 16NK-81 16TJ-53

TOTAL INVESTMENT 17 700 000 13 204 000 44 893 151 58 100 671 COSTS [SEK] OPERATING 27 193 151 44 896 671 PROFITS: ELECTRICITY - 9 934 004 - 18 689 819 PRODUCTION [SEK] TOTAL [SEK] 34 959 146 39 410 852

5. RESULTS

When cooling demand is 10% lower, it is only necessary one 16NK-81 double-effect absorption chiller (one less) and, therefore, only one OCT09HB05-5-90 (Vestas Aircoil) cooling tower too. Regarding demanded cooling in winter, 351 kW are just required.

Following Table 34. and Table 35. gather together new total cooling load as well as operational conditions and total costs, respectively.

Table 34. Operational conditions of different chillers sets in Mackmyra production site during the year when the cooling demand is 10% lower than the estimated one TOTAL TOTAL STEAM TOTAL BIOFUEL TOTAL WATER TOTAL COOLING ELECTRICITY SUPPLY CONSUMPTION CONSUMPTION LOAD [MWh/year] SUPPLY [MWh/year] [MWh/year] [m3/year] [MWh/year]

FREE ABSORP. 16NK-81 16TJ-53 16NK-81 16TJ-53 16NK-81 16TJ-53 16NK-81 16TJ-53 COOL. COOL.

337,93 8 030,28 7 036,80 13 240,73 511,07 498,42 10 062,62 18 934,24 27 893,3 34 148,2

Table 35. Total costs of Mackmyra absorption cooling plants for 10 years when the cooling demand is 10% lower than the estimated one 16NK-81 16TJ-53

TOTAL INVESTMENT 9 905 000 9 506 000 32 734 801 47 097 672 COSTS [SEK] OPERATING 22 829 801 37 591 672 PROFITS: ELECTRICITY - 8 127 503 - 15 293 040 PRODUCTION [SEK] TOTAL [SEK] 24 607 298 31 804 632

5. RESULTS

5.1.4.3. JOHANNES

The installations remain the same in Johannes production site when cooling demand is 10 % higher or lower. Cooling load and hence, operational conditions are only changed.

Next Table 36. and Table 38. show the new operational conditions and Table 37. and Table 39. the consistent new total costs.

Table 36. Operational conditions of different chillers sets in Johannes production site during the year when the cooling demand is 10% higher than the estimated one TOTAL TOTAL HOT TOTAL ABSORPTION TOTAL BIOFUEL TOTAL WATER WATER ELECTRICITY COOLING CONSUMPTION CONSUMPTION SUPPLY SUPPLY LOAD [MWh/year] [m3/year] [MWh/year] [MWh/year] [MWh/year] 7 353,12 10 991,43 1 268,15 13 959,11 28 753,8

Table 37. Total costs of Johannes absorption cooling plants for 10 years when the cooling demand is 10% higher than the estimated one 16LJ-53 TOTAL INVESTMENT 8 800 000 45 664 168 COSTS [SEK] OPERATING 36 864 168 PROFITS: ELECTRICITY - 24 543 860 PRODUCTION [SEK] TOTAL [SEK] 21 120 308

Table 38. Operational conditions of different chillers sets in Johannes production site during the year when the cooling demand is 10% lower than the estimated one TOTAL TOTAL HOT TOTAL ABSORPTION TOTAL BIOFUEL TOTAL WATER WATER ELECTRICITY COOLING CONSUMPTION CONSUMPTION SUPPLY SUPPLY LOAD [MWh/year] [m3/year] [MWh/year] [MWh/year] [MWh/year] 6 639,31 9 923,21 1 241,36 2 079 408,443 28 324,8

Table 39. Total costs of Johannes absorption cooling plants for 10 years when the cooling demand is 10% lower than the estimated one 16LJ-53 TOTAL INVESTMENT 8 800 000 43 140 656 COSTS [SEK] OPERATING 34 340 656 PROFITS: ELECTRICITY - 22 158 526 PRODUCTION [SEK] TOTAL [SEK] 20 982 130

5. RESULTS

5.2. COMPRESSION TECHNOLOGY VERSUS ABSORPTION TECHNOLOGY. COMPARISON FOR LEAF PRODUCTION SITE

Technological possibilities and aspects of absorption cooling systems at three specific sites in the victinity of Gävle, as well as the costs and profits (economic aspects), have been evaluated. Nevertheless, the main aim of this thesis is to analyze possible benefits with the use of heat driven absorption chillers instead of conventional vapour compressor chillers. Thus, compression cooling machines at LEAF have been replaced by equivalent absorption ones in order to make a comparison.

Compression cooling installation (see Appendix 1.) will be made up of five chillers: VKA1 (1254 kW), VKA2 (1254 kW), VKA3 (717 kW), VKA4 (3226 kW) and VKA5 (3226 kW), which are going to be replaced except for VKA3, as it is a back-up chiller that would be also used in the absorption cooling plant. The rest of the installation (building, pumps and so on)29 as well as operational conditions30 remain the same.

This way, four double-effect steam fired absorption chillers are going to be introduced: two 16NK-41 (1371 kW) and other two 16NK-71 (3446 kW), which has been choosen taking into account different sizes and models of chillers that exist in the market. Both VKA1 and VKA2 could be replaced with just a single bigger absorption machine (16NK-62); nevertheless, five machines ought to be in total so that absorption cooling installation would have been also built in two stages31. Likewise, an installation with single-effect absorption chillers is not

29 KM1 pumps are not taken into consideration as electricity consumption of absorption chillers, which belongs with pumps, is calculated. Regarding distribution pumps, those are taken into account in this case as they are also included in the costs of the refrigeration compression installation. 30 Compression cooling plant is using free cooling not only in winter but all around the year except for May-August (altogether 1936 h/year). Even though it is not right (it should be used only in winter time: ≈ 15 November-15 March), the same operational conditions have been considered so that new calculations are comparable with the existing compression project. 31 There are only VKA1 and VKA2 cooling machines in the first stage of the compressor refrigerant cooling project and one of them is a back-up chiller. For that reason, there are two small compressor chillers when the installation is totally built (in addition to VKA4 and VKA5) instead of a bigger one.

5. RESULTS

studied since more than four absorption chillers would be needed (their maximum capacity is 2461 kW).

Next, all calculations are shown.

Table 40. Operational conditions of the existing cooling project but with absorption machines CAPACITY [kW] OPERATING TIME VKA1 →16NK-41,1 VKA4 →16NK-71,1 [h/year] VKA2 →16NK-41,2 VKA5 →16NK-71,2 44,28 1254 3226 487,08 940,5 2419,5 605,16 627 1613 339,48 315,5 806,5

Table 41. Power and steam demand of chillers set for the required cooling load in the existing cooling project but with absorption machines VKA1 →16NK-41,1 VKA4 →16NK-71,1 TOTAL VKA2 →16NK-41,2 VKA5 →16NK-71,2 [MWh/year] STEAM SUPPLY TO THE CHILLERS 2 * 876,51 2 * 2249,84 6252,67 [MWh/year] TOTAL POWER SUPPLY TO THE CHILLERS 2 * 9,78 2 * 15,99 51,53 [MWh/year] TOTAL BIOFUEL CONSUMPTION 2 * 1253,42 2 * 3217,30 8941,37 [MWh/year]

Table 42. Operational costs in the existing cooling project but with absorption machines ELECTRICITY [SEK/year] CHILLERS 51 530,11 - 1 SEK/kWh- REST OF THE EQUIPMENTS 3 192 656 BIOFUEL [SEK/year] - 165 SEK/MWh- 1 475 326,19 TOTAL [SEK/year] 4 719 512,30

Table 43. Total costs of the existing cooling project but with absorption machines for 10 years VK3 600 000 COOLING 16NK-41 2 * 3 000 000 EQUIPMENTS 16NK-71 2 * 5 300 000 INVESTMENT COSTS BUILDING 4 000 000 [SEK] PIPES INSIDE THE BUILDING 4 500 000 PUMPS AND FILTERS 3 000 000 INSIDE THE BUILDING TOTAL 28 700 000 COSTS OF OPERATION [SEK] 47 195 123 PROFITS: ELECTRICITY PRODUCTION [SEK] - 11 073 544 - 770 SEK/MWh- TOTAL [SEK] 64 821 579

5. RESULTS

Next Figure 32. gathers together all information about both cooling installations at LEAF.

8941 MWh 1438 MWh electricity biofuel to the grid 165 SEK/MWh ORC 770 SEK/MWh = 170 000 x when x = 1 x: years MAINTENANCE α = 0,23 COSTS = 340 000 – 10 200 x when 1 < x ≤ 5 3245 MWh [SEK] 6253 MWh electricity = 289 000 + 89 250 (x – 5) when x ≥ 6 steam 0,001 SEK/MWh 4241 MWh electricity ABSORPTION COOLING INSTALLATION 7143 MWh 0,001 SEK/MWh COMPRESSION COOLING INSTALLATION 7143 MWh

28 700 000 SEK COOLING 22 629 000 SEK COOLING

TOTAL COSTS FOR 10 YEARS: TOTAL COSTS FOR 10 YEARS: 64 821 579 SEK 66 204 500 SEK

(profits due to electricity production are taken into account)

Figure 32. Comparison of cooling installations with absorption and compression machines at LEAF

5. RESULTS

5.3. DISTRIBUTION SYSTEM

5.3.1. INSTALLATION

The most important information about the main networks is gathered in the following Table 44. Calculations and estimations, as well as all explanations, are presented in Appendix 5.

Table 44. Data about the distribution systems INTERNAL EXTERNAL CHILLED ΔP PIPE DIAMETER DIAMETER PRODUCTION DISTANCE WATER [kPa] KWH PE OF THE OF THE SITE [m] FLOW (in the (PN10) PIPE PIPE, 3 distribution [m /h] system) [mm] dn [mm] LEAF LEAF 1370 175 200 771 328 Mackmyra I 500 262 315

MACKMYRA Mackmyra II 310 166 200 317 250

Mackmyra III 1890 203 250 JOHANNES Johannes 1775 370 450 171 718

5.3.3. COST OF THE MAIN PIPING NETWORKS

Total costs of the distribution systems for each of the three studied sites can be seen in the next Table 45. They are made up of cost for distribution pumps and pipes; the later one includes, apart from the material (pipe itself), digging, construction and calculation plus quality control costs. Moreover, Table 46. gathers together power consumption of the distribution pumps as well as operational costs. For further information, see Section A5.2. in Appendix 5.

Table 45. Cost of the distribution systems PRODUCTION PUMP COST PIPES COST TOTAL COSTS SITE [SEK] [SEK] [SEK] LEAF 110 000 6 850 000 6 960 000 MACKMYRA 62 000 16 621 100 16 683 100 JOHANNES 69 000 9 577 900 9 646 900

Table 46. Operational conditions and costs of distribution pumps ELECTRIC POWER SUPPLY OPERATIONAL PRODUCTION SITE TO DISTRIBUTION PUMPS COSTS [SEK/year] [MWh/year] - 1 SEK/kWh- LEAF 336,04 336 040 MACKMYRA 119,39 119 390 JOHANNES 193,20 193 200

CHAPTER 6

Discussions

Amount of provided information was limited and to collect accurate information was difficult. Therefore, results are only approximations, as they are based on quiet a lot assumptions. As a result, definitive conclusions cannot be come up with.

6.1. PRODUCTION PLANTS

To finish with this research, one of the tasks is to make a decision about more adequate types of absorption chillers to be used. In the case of Johannes cooling production plant, hot-water absorption cooling machines ought to be introduced as there are no more options from the technical point of view. Regarding the other two sites, investment costs are higher for double-effect steam fired chillers than for single-effect ones, whereas operational costs are much more, about 50%, lower. Both scenarios, LEAF and Mackmyra, can be examined in depth.

On the one hand, investment costs for double-effect installation are 4 207 000 SEK higher at LEAF. Nevertheless, operational costs are 3 713 268 SEK lower per year, which means that the initial extra costs would be paid back in less than 2 years. If profits due to electricity output are taken into consideration, the difference in annual costs would not be so large, but still 903 778 SEK/year (in this case, higher investment costs would be paid back in 5 years).

On the other hand, despite double-effect facilities cost 8 194 000 SEK more than single-effect ones at Mackmyra, operational costs are

6. DISCUSSIONS

1 590 110 SEK lower per year. As a result, the extra investment costs are paid back in 5 years. This time rises up to 10 years if produced electricity is taken into account.

Therefore, needless to say that it is more profitable to introduce double- effect chillers in both sites, since the pay-back times for extra investments are short and the earnings would be considerable. This way, costs and profits for the possible future three absorption cooling plants in Gävle would be those that are gathered together in the following Table 47.

Table 47. Most adequate chillers and costs & profits for the three production sites PROFITS OPERATIONAL FROM PRODUCTION ABSORPTION INVESTMENT COSTS ELECTRICITY SITE CHILLERS SETS COST [SEK] [SEK/year] PRODUCTION [SEK/year] 3 double-effect LEAF chillers (4652 kW) 22 627 000 4 753 785 3 183 656 in parallel 2 double-effect MACKMYRA chillers (4652 kW) 17 700 000 2 504 835 903 122 in parallel 2 single-effect hot water chillers JOHANNES 8 800 000 3 561 396 2 335 649 (1846 kW) in parallel

Next graph in Figure 33. shows total heat that might be produced in different biofuel boilers for the three absorption plants and accordingly obtained extra electricity output.

6. DISCUSSIONS

Figure 33. Increased heat load for the three absorption plants and the possible extra electricity that would be produced

In Figure 23. was shown that when the load in the district heating network is low there is almost none electricity production in Johannes CHP plant. In addition, it is shut down during summer, June-August. If heat driven absorption chillers were introduced, heat load and therefore, electricity output, would be increased as it is shown in the next graph in Figure 34.

Figure 34. Increased heat and electricity load in the probable Johannes trigeneration plant

6. DISCUSSIONS

Nevertheless, this heat load would not be even enough to keep the boiler running during summer because of efficiency problems, that is, the minimum working capacity. The graph in Figure 35. shows that the boiler would have to work at around 5 MW, whereas it is shut down when the loading is lower than 25% of its maximum capacity (20 MW).

Figure 35. Required operational conditions of the boiler for the cooling plant at Johannes

Consequently, cooling production at Johannes is a contribution but at present it is not possible to keep the plant running during summer because of the minimum load problem. It might be feasible if either heat or cooling market grew in the future.

6.2. MOST PROFITABLE TECHNIQUE FROM ECONOMIC POINT OF VIEW. SUSTAINABILITY

Next graph in Figure 36. depicts all costs for the two different cooling systems with absorption and vapour compressor technologies at LEAF. It has to be underlined that the comparison is limited since water from the river is used for cooling down the chillers and one of the main differences between these machines is the required size of cooling towers.

6. DISCUSSIONS

Figure 36. Comparison of total costs for ten years for the different cooling production technologies at LEAF

The larger investment costs of the absorption cooling compared to compression cooling, 6 071 000 SEK, are paid back after five years (4,39 years) because of lower electricity consumption and larger fuel utilization32, in addition to increased electricity production.

Next Table 48. gathers together annual benefits after the first 10 years when using absorption chillers instead of compression cooling machines:

Table 48. Annual benefits of absorption cooling technology at LEAF after 10 years PROFITS ELECTRICITY ELECTRICITY FROM CASE CONSUMPTION PRODUCTION ELECTRICITY [MWh/year] [MWh/year] [SEK/year] LEAF 8905 kW - 996 1438 1 107 354

32 It bears reminding from Section 2.3. that absorption systems can compete against compression ones when price of electricity is around 8 times higher than cost of heat.

6. DISCUSSIONS

An efficiency comparison between system including absorption or vapour compressor chillers can be made too. If overall system is taken into account, total efficiency for compressor cooling system is 58% higher33. Nevertheless, if internal electricity consumption is analyzed, the coefficient of performance 34 (COPel) is 23% greater for the absorption machines’ installation , as absorption chillers only use electricity for pumping the absorbent solution whereas compression ones are driven by electric power.

Deregulation and real-time pricing for electricity give an incentive to manage electrical loads. A compression chiller is a very big target when looking for ways to reduce electrical loading and to control costs. Thus, absorption units allow it without sacrificing either performance or reliability.

Moreover, as mentioned before, an absorption cooling system contributes to an increased electricity production. Hence, it gives good opportunities of utilizig the biofuel in an effective way.

This way, it is come to the conclusion that a sustainable energy system for Gävle for meeting the cooling demand can be the erection of district cooling networks with trigeneration plants by producing cooling in heat driven absorption cooling machines. Increasing of the energy system with a third output (cooling) would optimize the system even more. Furthermore, it is also very good from environmental point of view, since extra electricity produced could be sold as green in the Swedish market and it could replace, this way, margin produced electricity.

It bears mentioning that the system border of electricity production and consumption has to be taken into consideration when studying environmental aspects and, like this, carbon dioxide emissions. From global point of view, electricity production in Gävle would affect European energy system and total

33 ηTOT, compression system = Wcooling/Welectricity = 1,684 ηTOT, absorption system = (Wcooling + Welectricity)/(Qfuel + Welectricity) = 0,705

34 COPel, compression chillers set = Wcooling/Welectricity = 1,684 COPel, absorption chillers set = Wcooling/Welectricity = 2,201

6. DISCUSSIONS

CO2 emissions would be therefore negative. However, the local emissions would be negatively affected because of increased use of fuel; anyway, biofuel, that is, clean fuel, would be used.

6.3. COOLING DEMAND VERSUS COSTS AND BENEFITS OF ABSORPTION COOLING TECHNOLOGY

There are three scenarios that it does not even compare at all to each other as the installations are quiet different. Even though double-effect steam fired chillers might be at both LEAF and Mackmyra production sites, water from the river could be used for cooling down the chillers at LEAF whereas cooling towers are required at Mackmyra, which entails electricity consumption and higher investment costs for the latest case. Regarding Johannes production site, although it also needs cooling towers, steam is not used, but hot water.

As a result, each case is going to be studied separately.

6.3.1. ELECTRICITY PRODUCTION AND CONSUMPTION

The environmental and economical effects with absorption systems compared with vapour compression ones are consistently positive and become more and more evident with higher cooling demands and higher electricity prices (note Figure 37. in the next page).

6. DISCUSSIONS

Figure 37. Electricity production and consumption according to the cooling demand in three different scenarios

6.3.2. COSTS AND PROFITS. THE BEST OPTIONS

JOHANNES

Figure 38. Costs and profits (due to electricity production) according to the cooling demand in three different scenarios

Johannes absorption cooling plant with hot-water chillers is the smallest one. The previous graph in Figure 38. shows how investment costs are kept

6. DISCUSSIONS

constant with variations of ±10% in cooling demand. This means the same machines can be used to produce up to 10% more than required cooling nowadays with higher profits, as electricity output together with income from customers increase while variation in costs of operation is little.

On the other hand, steam-fired chillers are under study. The trend at LEAF is the same as at Johannes. However, there is a big difference at Mackmyra when demand decreases by 10%: investment costs are 44% lower. Therefore, the best option would be to build smaller installations and meet the cooling demand in Kungsbäck area by other means. This could be accomplished in two different ways: by storing energy or by making the network smaller and using another.

The university, which cooling demand is 1,8 MW, could be connected to the network in the city center, as it is not far away from Konserthuset (where the main pipe might reach). In addition, as mentioned earlier, there would be no problem to produce required extra cooling with the same facility at LEAF. Research on advantages and disadvantages of this option could make possible the execution of a new thesis project.

Regarding energy storage, accumulator tanks for chilled water should be considered for many reasons: problems to fulfil the cooling demand, dynamic demand during the year, security in the system and so forth. Consecuently, further research into those systems could be done.

CHAPTER 7

Conclusions

This research seeks to compare compression and absorption cooling technologies and to make a decision about which one is the best solution, in addition to deal with the analysis of three trigeneration plants with absorption cooling systems in Gävle. In connection with this, next all interesting made conclusions are summed up and gathered together.

- Development of district cooling systems with trigeneration plants that produce chilled water in absorption machines is the best solution to meet the cooling demands.

Benefits with absorption systems compared with vapour compression ones become more and more evident with higher cooling demands and higher electricity prices.

- It is more profitable to introduce double-effect steam-fired absorption chillers than single-effect ones.

- Even though steam-fired chillers are more efficient, single-effect hot water chillers might be introduced at Johannes, as the pressure of the steam leaving the turbine is lower than the required one for steam fired cooling machines.

- The cooling plant at Johannes might be a contribution, but at present it is not feasible because of boiler´s minimum load problem.

- It would be more profitable to increase the production of cooling in 10% over the demand at LEAF and Johannes. Nevertheless, regarding Mackmyra production site, the best option would be to build smaller installations and meet the demand by other means.

REFERENCES

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[2] L. Trygg, B. G. Karlsson, Industrial DSM in a deregulated European electricity market-a case study of 11 plants in Sweden, Department of Mechanical Engineering, Division of Energy Systems, Linköping Institude of Technology, Linköping S-581 83, Sweden.

[3] A. Rojey, Cold producing process, 4,037,426 United States Patent.

[4] M. J. Moran, H. N. Shapiro, ―Fundamentos de termodinámica técnica” (Fundamentals of Engineering Thermodynamics), Reverté (2004). ISBN 84- 291-4313-0.

[5] United States Departament of Energy (DOE), Mississippi Cooling, Heating, and Power (micro-CHP) and Bio-fuel Center, micro- Cooling, Heating, and Power (m-CHP) Instructional Module, Mississippi State, MS 39762 (December 2005 First Printing).

[6] R. Gianfrancesco, Method and apparatus for the absorption-cooling of a fluid, 5,177,979 United States Patent.

[7] R. Darío Ochoa V., ‖Absorción como una alternativa de ahorro de energía” (Absorption as alternative for saving energy), Tecnología Empresarial S.A. (2003).

[8] A. Şencan, K. A. Yakut, S. A. Kalogirou, Exergy analysis of lithium bromide/water absorption systems, Renewable Energy 30 (2005) 645-657.

[9] G. Cohen, A. Rojey, Absorbers used in absorption heat pumps and refrigerators, 4,299,093 United States Patent.

[10] Y. Hassan, Cold from Waste Energy. The Absorrption System, Mechanical Department, Sudan University.

[11] D W Hudson, Gordon Brothers Industries Pty Ltd, Ammonia absoption refrigeration plant, The official journal of AIRAH (August 2002).

[12] I. Horuz, A comparison between ammonia-water and water-lithium bromide solutions in vapor absorption refrigeration systems, PII S0735- 1933(98)00058-X.

[13]M. Rydstrand, Heat driven cooling in district energy systems, KTH Chemical Engineering and Technology, Stockholm (2004). ISBN 91-7283-794-2.

[14] K.E. Herold, R.Radermacher, S. A. Klein, Absorptioni Chillers and Heat Pumps, CRC Press (1996). ISBN 0-8493-9429-9.

REFERENCES

[15] P. E. Nilsson, Achieving the Desired Indoor Climate. Elergy Efficiency Aspects od Systen Design, Studentlitteratur, Lund (2003). ISBN 91-44-03235- 8.

[16] M.A. Rosen, M. N. Le, I. Dincer, Efficiency analysis of a cogeneration and district energy system, Applied Thermal Engineering 25 (2005) 147-159.

[17] F. Lin, J. Yi, Y. Weixing, Q. Xuzhong, Influence of supply and return water temperatures on the energy consumption of a district cooling system, Applied Thermal Engineering 21 (2001) 511-521.

INTERNET SOURCES:

1. http://www.air-conditioning-and-refrigeration-guide.com/refrigeration- cycle.html 2. http://www.qrg.northwestern.edu/thermo/design-library/refrig/refrig.html, Design of Vapour-Compression Refrigeration Cycles 3. http://www.commercial.carrier.com, Absorption Chillers 4. http://www.nationmaster.com/encyclopedia/Gas-absorption-refrigerator 5. http://www.grappa.co.yu/b/index.php?page=shop.getfile&file_id=36&product_ id=48&option=com_virtuemart&Itemid=30, Carrier-Sanyo Super Absorption 16LJ 11-53 6. http://www.kwhpipe.com 7. http://www.carrier.com 8. http://www.turboden.it/en/products.asp

BROCHURES:

1. 16TJ Single-Effect Steam-fired chillers (Carrier-Sanyo). 2. 16NK Double-Effect Steam-Fired Absorption Chillers (Carrier-Sanyo). 3. 16LJ Single-Effect Hot water-fired chillers (Carrier-Sanyo). 4. The Complete Pipework Solution (KWH Pipe). 5. PE Pressure Pipe Systems (KWH Pipe). 6. OCR technology, biomass application (TURBODEN).

REFERENCES

PERSONAL CONTACTS:

Table R. 1. Information about personal contacts NAME COMPANY/ CAPACITY INFORMATION AREA OF EXPERTISE Åke Björnwall Gävle Energi AB: Project & Development Tel direct 026 – 17 86 15 - General Supervisor [email protected] - Gävle Energi Håkan Rannestig Gävle Energi AB: Manager P&U 026-17 26 60 Cooling project

Ulf Hedman Ramböll Sverige AB (www.ramboll.se) Tel direct 026-149507 - Boiler-projects Consultant [email protected] - Absorption cooling Anders Kedbrant SWECO Systems AB (www.sweco.se) Tel direct 026-66 20 02 - Existing project Consultant Mobil 0706-623262 - Compression [email protected] Refrigeration Per-Arne Vahlund Gävle Energi AB: Marketing 026-17 86 80 Customer data Inger Wiklund Gävle Energi AB: Documentation 026-17 86 59 GIS Greger Berglund Gävle Energi AB: Project Manager 026-17 85 25 Distribution system

Lucas Enström Gävle Energi AB: Operation Manager 026-17 26 65 Johannes CHP plant [email protected] Daniel Widman Falu Energi & Vatten AB : Project Manager Tel direct 023-77049052 District Cooling project in [email protected] Falun

- Sale assistants: Tomas Lundgren and Tyko Sandell from Carrier, Thomas Nyström from Z&I Pumps, Anna Schlegel from Grudfos, Robert Lindberg from Baltimore Air Coil (BAC), etc.

APPENDICES

Appendix 1. PLANNED REFRIGERANT COMPRESSION INSTALLATION

A1.1. INSTALLATION

Figure A1. 1. Draft of the whole compression installation (Source: Anders Kedbrant, SWECO)

Appendix 1. Planned refrigeration compression installation

nd 2 stage 1st stage

2nd stage 1st stage

Figure A1. 2. Draft of the devices of the compression installation (Source: Anders Kedbrant, SWECO)

Appendix 1. Planned refrigeration compression installation

 INSTALLATION ON ITS FIRST STAGE - Submersible pumps for the whole installation: KM1-P6A and KM1-P6B - Main pumps for the distribution pipes: KB1-P6A and KB1-P6B

► Cooling water in the distribution system: FORWARD PIPE: 5,5 °C

RETURN PIPE: 13,2 °C

- 2 cooling machines (compressor, evaporator, condenser): VKA1 and VKA2 o 2 dry single pumps: KB1-P1 and KB1-P2 o 2 dry single pumps: KM1-P1 and KM1-P2 (they keep set flow in the condenser). - Heat exchanger unit: KB1-VVX1

 MACHINES AND DEVICES TO BE INTRODUCED IN THE SECOND STAGE - 3 cooling machines (compressor, evaporator, condenser): VKA3, VKA4 and VKA5 o 3 dry single pumps: KB1-P3, KB1-P4 and KB1-P5 o 3 dry single pumps: KM1-P3, KM1-P4 and KM1-P5

PUMPS:

Table A1. 1. Pump specifications of compression cooling installation I KM1-P6A / P6B TYPE (SUBMERSIBLE, BRUNN1, BRUNN2) DRY SINGLE PUMP PROCEDURE Wilo / FA 25.93D WITH ENGINE FK34.1- 6/50 MEDIA WATER 20°C FLOW 265 l/s MAXIMUM PRESSURE 150 kPa POWER 75 kW RATED CURRENT 151 A MINIMUM EFFICIENCY 88 %

Appendix 1. Planned refrigeration compression installation

Table A1. 2. Pump specifications of compression cooling installation II TYPE KB1-P6A / P6B Grundfos / : TP300/590/4 A-F-A DBUE or PROCEDURE equivalent MEDIA WATER 5,5°C FLOW 320 l/s MAXIMUM PRESSURE 400 kPa POWER 200 kW RATED CURRENT 340/196 A MINIMUM EFFICIENCY ---

Table A1. 3. Pump specifications of compression cooling installation III TYPE KB1-P1, KB1-P2 DRY SINGLE PUMP PROCEDURE Wilo / : IL 150/190-5,5/4 or equivalent MEDIA WATER 5,5°C FLOW 45 l/s MAXIMUM PRESSURE 50 kPa POWER 5,5 kW RATED CURRENT 11,4 A MINIMUM EFFICIENCY 71 %

Table A1. 4. Pump specifications of compression cooling installation IV TYPE KB1-P3 DRY SINGLE PUMP PROCEDURE Wilo / IL 80/170-2,2/4 MEDIA WATER 5°C FLOW 25 l/s MAXIMUM PRESSURE 50 kPa POWER 2,2 kW RATED CURRENT 4,7 A MINIMUM EFFICIENCY 67 %

Table A1. 5. Pump specifications of compression cooling installation V TYPE KB1-P4, KB1-P5 DRY SINGLE PUMP PROCEDURE Wilo / IL 200/240-15/4 MEDIA WATER 5°C FLOW 110 l/s MAXIMUM PRESSURE 70 kPa POWER 15 kW RATED CURRENT 28,5 A MINIMUM EFFICIENCY 76 %

Appendix 1. Planned refrigeration compression installation

Table A1. 6. Pump specifications of compression cooling installation VI TYPE KM1-P1, KM1-P2 DRY SINGLE PUMP PROCEDURE Wilo / IL 100/170-3/4 MEDIA WATER 20°C FLOW 40 l/s MAXIMUM PRESSURE 45 kPa POWER 3 kW RATED CURRENT 6,4 A MINIMUM EFFICIENCY 73 %

Table A1. 7. Pump specifications of compression cooling installation VII TYPE KM1-P3 DRY SINGLE PUMP PROCEDURE Wilo / IL 100/160-2,2/4 MEDIA WATER 5°C FLOW 30 l/s MAXIMUM PRESSURE 45 kPa POWER 2,2 kW RATED CURRENT 4,7 A MINIMUM EFFICIENCY 77 %

Table A1. 8. Pump specifications of compression cooling installation VIII TYPE KM1-P4, KM1-P5 PROCEDURE DRY SINGLE PUMP Wilo / IL 200/240-7,5/6 MEDIA WATER 5°C FLOW 80 l/s MAXIMUM PRESSURE 50 kPa POWER 7,5 kW RATED CURRENT 16 A MINIMUM EFFICIENCY 74 %

CHILLERS:

Table A1. 9. Vapour Compressor chillers specifications I VKA1, VKA2 TYPE MODEL: YRWCWCT3550C REFRIGERANT R134 A MAXIMUM CAPACITY 1254 kW INPUT POWER 187 kW VOLTAGE 400/ 50 Hz

Appendix 1. Planned refrigeration compression installation

Table A1. 10. Vapour Compressor chillers specifications II VKA3 TYPE MODEL: YRTBTBT0550C REFRIGERANT R134 A MAXIMUM CAPACITY 717 kW INPUT POWER 110 kW VOLTAGE 400/ 50 Hz

Table A1. 11. Vapour Compressor chillers specifications III VKA4, VKA5 TYPE MODEL: YKKKKLH95CQF REFRIGERANT R134 A MAXIMUM CAPACITY 3226 kW INPUT POWER 451 kW VOLTAGE 400/ 50 Hz

FREE COOLING HEAT EXCHANGER UNIT:

Table A1. 12. Heat exchanger specifications of compression cooling installation TYPE/MANUFACTURER KB1-VVX1 AlfaLaval CAPACITY 500 kW 4,5/15 ºC (primary) STREAMS TEMPERATURE 5,5/165 ºC (secondary) FLOW 11,3 l/s (primary & secondary) 96,9 kPa (primary) PRESSURE DROP 98,8 kPa (secondary)

VKA2 is a back-up chiller in the first stage. When the second stage is built, both VKA1 and VKA2 will be working together with VKA4 and VKA5 and VKA3 will be the back-up chiller (it is not considered for calculations).

All calculations, which are shown next, are for the whole installation.

Appendix 1. Planned refrigeration compression installation

A1.2. COOLING LOAD

Table A1. 13. Operational conditions of VKA1 and VKA2 compressors (YRWCWCT3550C) in time steps OPERATING COOLING CAPACITY % OPERATING % LOAD COP TIME LOAD [kW] (during year) [h/year] [kWh/year] 100 1254 6,712 3 44,28 55 527,12 75 940,5 7,524 33 487,08 458 098,74 50 627,0 7,377 41 605,16 379 435,32 25 315,5 4,679 23 339,48 107 105,94 1476 TOTAL 1 000 167,12 (see Table A1. 15.)

Table A1. 14. Operational conditions of VKA4 and VKA5 compressors (YKKKKLH95CQF) in time steps OPERATING COOLING CAPACITY COP % OPERATING % LOAD TIME LOAD [kW] (during year) [h/year] [kWh/year] 100 3226,0 7,148 3 44,28 142 847,28 75 2419,5 7,830 33 487,08 1 178 490,06 50 1613,0 7,868 41 605,16 976 123,08 25 806,5 6,350 23 339,48 273 790,62 TOTAL 1476 2 571 251,04

NOTE: the following Table A1. 15. shows the operation hours.

Table A1. 15. Operating time for cooling delivering during the year Month Days hours/day hours/month January 31 8 248 February 28 8 224 March 31 8 248 April 30 8 240 May 31 12 372 June 30 12 360 July 31 12 372 August 31 12 372 September 30 8 240 October 31 8 248 November 30 8 240 December 31 8 248

Free cooling (1936 h/year)

Compression refrigeration (1476 h/year)

Appendix 1. Planned refrigeration compression installation

Thus, as there are two YRWCWCT3550C compressors and other two YKKKKLH95CQF,

TOTAL COOLING LOAD PRODUCED BY COMPRESSION REFRIGERATION TECHNOLOGY: 7 142 836,32 kWh/year

A1.3. INPUT LOAD AND COSTS

Table A1. 16. Power needed in the compression cooling installation during the year INPUT POWER OPERATING TIME INPUT [kW] [h/year] LOAD Winter Winter Shut down [kWh/year] time time compressors KM1-P6A 75 22,5 1476 1936 6260 295 110 KM1-P6B 75 22,5 1476 1936 6260 295 110

KB1-P6A 200 60 1476 1936 6260 786 960 KB1-P6B 200 60 1476 1936 6260 786 960

see VKA1/VKA2 Table ― 1476 ― ― 149 046,48 A1. 17.

FIRST STAGE FIRST KB1-P1 5,5 ― 1476 ― ― 8118 KB1-P2 5,5 ― 1476 ― ― 8118 KM1-P1 3 ― 1476 ― ― 4428 KM1-P2 3 ― 1476 ― ― 4428

KB1-VVX1 ― 500 ― 1936 968 000

see VKA2 Table ― 1476 ― ― 149 046,48 A1. 17. VKA3 110 ― ― ― ― ― see VKA4 Table ― 1476 ― ― 359 465,04 A1. 18. see VKA5 Table ― 1476 ― ― 359 465,04 A1. 18.

KB1-P3 2,2 ― ― ― ― ― SECOND STAGE SECOND KB1-P4 15 ― 1476 ― ― 22 140 KB1-P5 15 ― 1476 ― ― 22 140 KM1-P3 2,2 ― ― ― ― ― KM1-P4 7,5 ― 1476 ― ― 11 070 KM1-P5 7,5 ― 1476 ― ― 11 070

TOTAL 4 240 675,04

100

Appendix 1. Planned refrigeration compression installation

Working the whole year (when the compressors are shut down too) 30% of the total power is just used in winter time and when the compressors are not working It is ony used in winter time, when free cooling is allowed

NOTES: - Following Table A1. 17. and Table A1. 18. show input load for different compressors in time steps. Table A1. 17. Input load VKA1 and VKA2 compressors (YRWCWCT3550C) in time steps INPUT OPERATING INPUT % POWER TIME LOAD LOAD [kW] [h/year] [kWh/year] 100 187 44,28 8 280,36 75 140,25 487,08 68 312,97 50 93,5 605,16 56 582,46 25 46,75 339,48 15 870,69 TOTAL 1476 149 046,48

Table A1. 18. Input load VKA4 and VKA5 compressors (YKKKKLH95CQF) in time steps INPUT OPERATING INPUT % POWER TIME LOAD LOAD [kW] [h/year] [kWh/year] 100 451 44,28 19 970,28 75 338,25 487,08 164 754,81 50 225,5 605,16 136 463,58 25 112,75 339,48 38 276,37 TOTAL 1476 359 465,04

- Input loads for pumps should be calculated in the same way, as they depend on the cooling load (system curve). Nevertheless, their design curves are unkown and therefore, it has been considered they are working at their maximum capacity except for winter time (and when compressors are shut down too), when they work at 30% of the maximum capacity (minimum capacity).

101

Appendix 1. Planned refrigeration compression installation

Finally, Table A1. 19. gathers together total needed load in the system and operational costs.

Table A1. 19. Total input load and operating costs in the compression cooling installation TOTAL INPUT LOAD [kWh/year] 4 240 675 OPERATING COSTS [SEK/year] -1SEK/kWh- 4 240 675

A1.4. TOTAL COSTS

Table A1. 20. Costs of the compressor refrigerant system COOLING EQUIPMENTS 11 129 000

INVESTMENT BUILDING 4 000 000 COSTS PIPES INSIDE THE BUILDING 4 500 000 [SEK] PUMPS AND FILTERS 3 000 000 INSIDE THE BUILDING

TOTAL: 22 629 000 COSTS OF

OPERATION 4 240 675 [SEK/year] 2nd 3th 5th 6th 10th MAINTENANCE 1st year … … COSTS year year year year year [SEK] 159 800 149 600 139 400 … 119 000 89 250 89 250 89 250

Evolution of maintenance costs (it includes parts and working time, 412 h/year, of 2 people) is shown in Figure A1. 3. below:

Figure A1. 3. Maintenance costs in the course of time

102

Appendix 1. Planned refrigeration compression installation

A1.5. PAY-BACK TIME FOR THE INVESTMENTS

Table A1. 21. Pay-back times for the compression installation INVESTMENTS PAY-BACK TIME [years] COOLING EQUIPMENT (compression machine) 10 PIPES 20-30 PUMPS AND FILTERS 10

As the depreciation of equipments is in roughly 10 years (the investment is recovered), costs can be calculated for this period of time:

Table A1. 22. Total costs for the refrigeration compression system for the first 10 years INVESTMENT COSTS [SEK] 22 629 000 COSTS OF OPERATION [SEK] 42 406 750 MAINTENANCE COSTS 35 [SEK] 1 168 750 TOTAL [SEK] 66 204 500

Thus, TOTAL COSTS FOR 10 YEARS are: 66 204 500 SEK 6 620 450 (SEK/year)

Later on, after the first 10 years, there will be only operational and maintenance costs.

35 Total maintenance costs are equal to the area under the curve in Figure A1. 3. This way, they will be: (51000*5/2) + (119000-89250)*5 + (89250*10) = 1168750 SEK for ten years.

103

Appendix 2. EXPECTED COOLING DEMAND

A. CITY CENTER (LEAF)

Table A2. 1. Cooling demand of possible future customers in the city center and additional data NAME COOLING COOLING OWNER OF ADDRESS N° INSTALLED DEMAND NOTES ESTATE Yes No [KW] Kv Hövdingen, N skepparg 2 1 X 150 Kv Notanus, N Strandgatan 1 2 X 70 Kv Syndicus Kyrkogatan 4 3 X 200 Länsstyrelsen, Borgmästarplan 2 4 X Not interested Norrporten Polishuset S Centralg 1-3 5 X 350 New cooling system installed 2007 Kv Vulkanus S Sjötullsgatan 6 X 100 ‖Byggforskningen‖ Kv Vasen Lantmäterigatan 7 X 700 Kv Kapellbacken Skomakargatan 1 8 X 400 ‖Skattehuset‖ Kv. Klockstapeln Vågskrivargatan 5 9 X 200 Kv Gevalia Nygatan 25-27 10 X 250 Cooling machine installed 2004 Kv Skampålen 11 X 400 Present cooling system contain R22. Norrvidden Kv Lektorn 12 X 200 Cooling machine installed 1998 Norr 23:5 13 X 200 Old cooling machine which (‖Skandihuset‖) need to be replaced Postterminalen 14 X 100

Kv Nattväktaren 15 X 700 Cooling machine installed 2000 Diös Fastigheter Sankt George:1 16 X 40 Kv Hoppet 17 X 40 Kv Pechlin ―Folksamhuset‖ 18 X 100 New cooling machine installed 2005

104

Appendix 2. Expected cooling demand

Table A2.1 (continuation). Cooling demand of possible future customers in the city center and additional data NAME COOLING COOLING OWNER OF ADDRESS N° INSTALLED DEMAND NOTES ESTATE Yes No [KW] Alderholmen Building not erected yet. Gavlegårdarna 19 X 30 servicehus Kv Trähästen Förvaltningshuset 20 X 400 ―Sure‖ customer Gavlefastigheter Biblioteket ―The library‖ 21 X 700 ―Kommunhuset‖ 22 X 300 Teatern ―The theatre‖ 24 X 300 Need cooling solution Kv Tomväkaren Konserthuset 25 350 Problem with present solution Boultbee 26 Have two machines built 2004 Kv Kärrlandet ―Nian‖ 27 X 700 Cooling machines installed 2004. Gamla domstolarna 28 X 45 Existing customer Boetten Drottningatan 48 29 X 20 Kraft Foods Kv Alderholmen 30 X 500 100 kW sure, 400 kW potential Handelsbanken Kv Skolstuvan 31 X 200 Länsmuséet Kv Plantagen ―The museum‖ 32 X 250 Jernhusen station AB Centralstationen ―Railway station‖ 33 X 60 New cooling machines installed 2005. Banverket Kv Storön 34 X 100 Need to expand present capacity Allokton Kv Gesällen 35 X 350 F2 Hyresbostäder Kv Borgen 36 X 40 Folkets Hus 37 X 120 Not interested at present Kv islandsskolan 38 X 40 Norr 23:3 39 X 100 Contact by SWECO

105

Appendix 2. Expected cooling demand

Total cooling demand in the city center is 8905 kW (data for Konserthuset was missing but it has been considered slightly bigger than for the theatre because it is quite bigger building but activities going on there are similar). Nevertheless, taking into account that it is unkown cooling demand of some places (such as nº 26) and there could be more customers in the future, it is considered a cooling demand of 9000 kW. In addition, LEAF itself needs 2500 kW of cooling. Like this,

TOTAL COOLING DEMAND FOR LEAF PRODUCTION SITE: 11 500 kW

B. KUNGSBÄCK AREA (MACKMYRA)

Table A2. 2. Customers and their cooling demand in Kungsbäck CUSTOMER COOLING DEMAND [kW] HOSPITAL 1700 UNIVERSITY 1800 TECHNOLOGIC PARK 1000

4500 kW has to be delivered through the main pipe of district cooling distribution system that leaves the cooling production plant. However, it is needed to increase production output power since the whisky factory might use cold as well. Anyway, this cooling demand would not be much, as there is not any cooling system in the current factory and storage rooms that are planning to build would be underground, where temperature would be adequate (under 17 ºC). This way,

TOTAL COOLING DEMAND FOR MACKMYRA PRODUCTION SITE: ≈ 5000 kW

106

Appendix 2. Expected cooling demand

C. JOHANNESBERGSVÄGEN AREA (JOHANNES)

Table A2. 3. Cooling demand for Johannes production site CUSTOMER COOLING DEMAND [kW] HEMLINGBY SHOPPING CENTERS 2000

Cooling demand of possible customers in Johannesbergsvägen area is 2000 kW. Moreover, cooling is also used at Johannes CHP plant, mainly for the refrigeration of the turbine, which is produced by electrically driven devices. Thus, this cooling system could be also replaced and it is like this planning to produce the cooling needed too, which is roughly 1,3-1,4 MW, in the absorption plant. So,

TOTAL COOLING DEMAND FOR JOHANNES PRODUCTION SITE: 3400 kW

107

Appendix 3. SPECIFICATIONS AND CALCULATIONS REGARDING ABSORPTION COOLING INSTALLATIONS

A3.1. ABSORPTION CHILLERS

A.3.1.1. MODELS AND THEIR CHARACTERISTICS

A. LEAF AND MACKMYRA

- SINGLE-EFFECT STEAM-FIRED ABSORPTION CHILLERS: Carrier-Sanyo 16TJ

108

Appendix 3. Specifications and calculations regarding absorption cooling installations

(Source: Carrier-Sanyo)

109

Appendix 3. Specifications and calculations regarding absorption cooling installations

According to the brochure, 16TJ-53 absorption chiller consumes 5460 kg/h satured steam at 100 kPa. It is known that the enthalpy of satured vapour at 1 bar is 2675,5 kJ/kg [4] (Pressure Table of Properties of Satured Water), so:

kg 1 h kJ 5460 * * 2675,5 = 4057,84 kW satured steam h 3600 s kg Thus,

4,1 MW satured steam at 1 bar 16TJ - 53 2,5 MW cooling

ABSORPTION CHILLER

On the other hand, electric and cooling power to be supplied are:

P = 400V * 11,0 A * 0,8 (power factor that most generators use) = 3520 W

Pelectricity supply = 3,52 kW

P = 159 kg/s * 4,2 kJ/(kg.K) * (38,4 – 29,4) K= 6010,2 kW

Pcooling supply = 6,01 MW

Take note that the relation between capacity of the chiller used and cooling water power as well as steam needed can be considered linear (part-load curve is almost linear). However, the cooling water flow is usually constant. That is, i.e. an 16TJ-53 absorption chiller working at 50% of its maximum capacity (1230,5 kW) needs 2028,92 kW of satured steam and 3005,1 kW of cooling (the water flow is 159 l/s). With regards to the electric power supply (for pumps), it is constant.

110

Appendix 3. Specifications and calculations regarding absorption cooling installations

- DOUBLE-EFFECT STEAM-FIRED ABSORPTION CHILLERS: Carrier-Sanyo 16NK

111

Appendix 3. Specifications and calculations regarding absorption cooling installations

(Source: Carrier-Sanyo)

112

Appendix 3. Specifications and calculations regarding absorption cooling installations

According to the brochure, 16NK-81 absorption chiller consumes 5300 kg/h satured steam at 784 kPa. It is known that the enthalpy of satured vapour at 8 bar is 2769,1 kJ/kg [4] (Pressure Table of Properties of Satured Water), so:

kg 1 h kJ 5300 * * 2769,1 = 4076,71 kW satured steam h 3600 s kg

Thus,

4,1 MW satured steam at 8 bar 16NK - 81 4,7 MW cooling

ABSORPTION CHILLER

On the other hand, electric and cooling power to be supplied are:

P = 400V * 33,5 A * 0,8 = 10 720 W

Pelectricity supply = 10,72 kW

P = 333,9 kg/s * 4,2 kJ/(kg.K) * (35,4 – 29,4) K= 8414,28 kW

Pcooling supply = 8,41 MW

113

Appendix 3. Specifications and calculations regarding absorption cooling installations

B. JOHANNES

Figure A3. 1. Water streams (steam and DH) at Johannes CHP plant (Source: Gävle Energi AB)

114

Appendix 3. Specifications and calculations regarding absorption cooling installations

Next Table A3. 1. shows pressures of the first steam stream extracted from the turbine related to electricity and district heating production capacities during the year. The values in blue point out the steam cannot be used in absorption chillers. The last four values belong to summer period, when the boiler is running at its minimum capacity (20 MW).

Table A3. 1. Production data and pressure of the first steam stream extracted from the turbine (Source: Gävle Energi AB) ELECTRICITY DISTRICT HEATING P [MW] [MW] [kPa] 23,704 56,168 1 24,367 59,375 1,044 20,531 55,589 2,25 19,848 52,422 2,23 21,738 50,532 0,8835 11,137 34,355 2,13 10,679 32,022 2,12 12,687 30,004 0,5511 3,602 18,624 2,05 3,683 18,555 2,05 4,244 15,991 0,7415 4,449 15,723 0,7409 4,677 15,558 0,4139 4,877 15,28 0,4136

As the pressure of steam is not suitable during peak periods of cooling demand (summer)36, a steam-fired absorption machine cannot be introduced.

36 It is not considered the last steam stream leaving the turbine since its pressure is even lower.

115

Appendix 3. Specifications and calculations regarding absorption cooling installations

- SINGLE-EFFECT HOT WATER-FIRED ABSORPTION CHILLERS: Carrier-Sanyo 16LJ

116

Appendix 3. Specifications and calculations regarding absorption cooling installations

(Source: Carrier-Sanyo)

117

Appendix 3. Specifications and calculations regarding absorption cooling installations

According to the brochure, 16LJ-53 absorption chiller consumes 73 l/s hot water (95,0 °C → 86,0 °C) at its maximum cooling capacity. This is a heat supply of: P = m * Cp * ∆T P [kW] = 73 [kg/s] * 4,2 [kJ/kg K] * 9 [K] = 2759,4 kW

Pheat supply = 2759 kW

On the other hand, electric and cooling power to be supplied are:

P = 400V * 11,0 A * 0,8 = 3520 W

Pelectricity supply = 3,52 kW

P = 119,2 kg/s * 4,2 kJ/(kg.K) * (38,4 – 29,4) K= 4505,76 kW

Pcooling supply = 4,51 MW

A3.1.2. INVESTMENT COSTS

Next Table A3. 2. shows price and capacity comparison of different chillers (LJ and TJ units compared to NK units).

Table A3. 2. Price comparison of single- and double-effect units (Source: Carrier-Sanyo)

118

Appendix 3. Specifications and calculations regarding absorption cooling installations

Investment costs for different needed models are the followings (Table A3. 3.):

Table A3. 3. Investment costs for different absorption chiller units (Source: Ulf Hedman, Ramboll) ABSORPTION CHILLER PRICE [SEK] 16TJ-53 2 700 000 16LJ-53 2 700 000 16NK-81 6 200 000 16NK-71 5 300 000 16NK-41 3 000 000

A3.1.3. OPERATIONAL CONDITIONS

According to the estimations Anders Kedbrant did for refrigerant compression cooling project, the cooling demand load curve in the city center for 2008 is as shown in Figure A3. 2., which has been divided in different cooling power production periods.

8900

7568

5223

3624 2718

693

Figure A3. 2. Cooling demand load curve (2008) divided in periods according to the power needed to be produced

119

Appendix 3. Specifications and calculations regarding absorption cooling installations

Information from the previous graph (Figure A3. 2.) is gathered in Table A3. 4.

Table A3. 4. Average city center´s cooling demand in time steps for 2008 PRODUCTION COOLING HOURS % of max. TIME PERIOD DEMAND (reference: power 37 [kW] compression refrigeration project) Winter time: 693 7,79 964 15 November-15 March 15 March-1 April 2718 30,54 244 1-15 November April 3624 40,72 364 15 October-1 November 1-15 May 5223 58,69 430 15 September-15 October 15 May-15 June 7568 85,03 672 15 August-15 September Summer time: 8900 100 738 10 June-15 August

NOTE: There is no production of cooling in winter time, since free cooling is allowed (it is needed to introduce a heat exchanger).

Taking into account calculated percentages, cooling load during the year can be estimated for the three production sites that are subject of studying:

37 Information from first column can be translated into percentages taking the maximum power as reference.

120

Appendix 3. Specifications and calculations regarding absorption cooling installations

A. LEAF

Table A3. 5. Cooling load to be produced and working power of different chillers (double- and single- effect) at LEAF during the year COOLING NUMBER OF CHILLERS WORKING % of POWER & CAPACITY [kW] TIME PERIOD max. PRODUCTION power TSA-16NK-81 TSA-16TJ-53 [kW] 15 November-15 March 7,79 895,45 — — 15 March-1 April & 1-15 November 30,54 3512,02 3512 1756 1756 April & 15 October-1 November 40,72 4682,70 4652 (max.) 2342 2342 1-15 May & 15 September-15 October 58,69 6748,82 3375 3375 2250 2250 2250 15 May-15 June & 15 August-15 September 85,03 9778,88 3260 3260 3260 2445 2445 2445 2445 15 June-15 August 100 11500 3834 3834 3834 2300 2300 2300 2300 2300 NOTE: minimum working power of absorption chillers is 20% of their maximum capacity

Table A3. 6. Cooling power to be supplied to the chillers at LEAF during the year COOLING OF CHILLERS –free cooling- [kW] TIME PERIOD TSA-16NK-81 TSA-16TJ-53 15 November-15 March — — 15 March-1 April & 1-15 November 6352,31 4288,46 4288,46 April & 15 October-1 November 8414,28 5719,58 5719,58 1-15 May & 15 September-15 October 6104,51 6104,51 5494,9 5494,9 5494,9 15 May-15 June & 15 August-15 September 5896,51 5896,51 5896,51 5482,69 5482,69 5482,69 5482,69 15 June-15 August 6934,73 6934,73 6934,73 5617,01 5617,01 5617,01 5617,01 5617,01 NOTE: Heat exchangers are going to be calculated for cooling down the chillers when they are working at their maximum capacity (security margin, just in case). Although cooling water flow is better to be constant, in this case it needs to be changed as conditions of free cooling (temperature of water from the river), that is, the cooling power, cannot be controlled. Therefore, necessary water flow can be set by a valve just before it goes into the chillers.

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Appendix 3. Specifications and calculations regarding absorption cooling installations

Table A3. 7. Cooling load to be produced and working power of different chillers (double- and single- effect) at LEAF during the year when the cooling demand is 10% higher than the estimated one COOLING NUMBER OF CHILLERS WORKING % of POWER & CAPACITY [kW] TIME PERIOD max. PRODUCTION power TSA-16NK-81 TSA-16TJ-53 [kW] 15 November-15 March 7,79 1012,7 — — 15 March-1 April & 1-15 November 30,54 3970,2 3970 1985 1985 April & 15 October-1 November 40,72 5293,6 2647 2647 1766 1766 1766 1-15 May & 15 September-15 October 58,69 7529,7 3815 3815 1908 1908 1908 1908 15 May-15 June & 15 August-15 September 85,03 11053,9 3685 3685 3685 2211 2211 2211 2211 2211 15 June-15 August 100 13000 4334 4334 4334 2600 2600 2600 2600 2600 2600

Table A3. 8. Cooling power to be supplied to the chillers at LEAF during the year when the cooling demand is 10% higher than the estimated one COOLING OF CHILLERS –free cooling- [kW] TIME PERIOD TSA-16NK-81 TSA-16TJ-53 15 November-15 March — — 15 March-1 April & 1-15 November 7180,72 4847,72 4847,72 April & 15 October-1 November 4787,75 4787,75 4312,89 4312,89 4312,89 1-15 May & 15 September-15 October 6900,36 6900,36 4659,68 4659,68 4659,68 4659,68 15 May-15 June & 15 August-15 September 6665,22 6665,22 6665,22 5399,66 5399,66 5399,66 5399,66 5399,66 15 June-15 August 7839,10 7839,10 7839,10 6349,66 6349,66 6349,66 6349,66 6349,66 6349,66

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Appendix 3. Specifications and calculations regarding absorption cooling installations

Table A3. 9. Cooling load to be produced and working power of different chillers (double- and single- effect) at LEAF during the year when the cooling demand is 10% lower than the estimated one COOLING NUMBER OF CHILLERS WORKING % of POWER & CAPACITY [kW] TIME PERIOD max. PRODUCTION power TSA-16NK-81 TSA-16TJ-53 [kW] 15 November-15 March 7,79 779 — — 15 March-1 April & 1-15 November 30,54 3054 3054 1527 1527 April & 15 October-1 November 40,72 4072 4072 2036 2036 1-15 May & 15 September-15 October 58,69 5869 2935 2935 1957 1957 1957 15 May-15 June & 15 August-15 September 85,03 8503 4252 4252 2126 2126 2126 2126 15 June-15 August 100 10000 3334 3334 3334 2000 2000 2000 2000 2000

Table A3. 10. Cooling power to be supplied to the chillers at LEAF during the year when the cooling demand is 10% lower than the estimated one COOLING OF CHILLERS –free cooling- [kW] TIME PERIOD TSA-16NK-81 TSA-16TJ-53 15 November-15 March — — 15 March-1 April & 1-15 November 5523,91 3729,21 3729,21 April & 15 October-1 November 7365,21 4972,27 4972,27 1-15 May & 15 September-15 October 5308,57 5308,57 4779,34 4779,34 4779,34 15 May-15 June & 15 August-15 September 7690,78 7690,78 5192,07 5192,07 5192,07 5192,07 15 June-15 August 6030,35 6030,35 6030,35 4884,36 4884,36 4884,36 4884,36 4884,36

123

Appendix 3. Specifications and calculations regarding absorption cooling installations

B. MACKMYRA

Table A3. 11. Cooling load to be produced and working power of different chillers (double- and single- effect) in Mackmyra production site during the year COOLING NUMBER OF CHILLERS WORKING % of POWER & CAPACITY [kW] TIME PERIOD max. PRODUCTION power TSA-16NK-81 TSA-16TJ-53 [kW] 15 November-15 March 7,79 389,33 — — 15 March-1 April & 1-15 November 30,54 1526,97 1527 1527 April & 15 October-1 November 40,72 2035,96 2036 2036 1-15 May & 15 September-15 October 58,69 2934,27 2934 1467 1467 15 May-15 June & 15 August-15 September 85,03 4251,69 4252 2126 2126 15 June-15 August * 100 5000 2500 2500 2461 (max.) 2461 * TSA-16TJ- 53. Back-up chiller can be used to produce extra cooling (78 kW) which is needed

Table A3. 12. Cooling power to be supplied to the chillers during the year and necessary cooling towers in Mackmyra production site COOLING OF CHILLERS [kW] COOLING TOWERS NEEDED TIME PERIOD TSA-16NK-81 TSA-16TJ-53 TSA-16NK-81 TSA-16TJ-53

15 November-15 March — — Capacity: 7691 kW Capacity: 6010 kW 15 March-1 April & 1-15 November 2762,12 3729,21 Flow: 1202,04 m3/h Flow: 572,4 m3/h April & 15 October-1 November 3682,60 4972,27 ΔTmax. = 5,76 K ΔTmax. = 9 K 1-15 May & 15 September-15 October 5306,86 3582,68 3582,68 Capacity: 4523 kW Capacity: 6010 kW 15 May-15 June & 15 August-15 September 7690,78 5192,07 5192,07 Flow: 1202,04 m3/h Flow: 572,4 m3/h 15 June-15 August 4522,14 4522,14 6010,2 6010,2 ΔTmax. = 3,39 K ΔTmax. = 9 K

124

Appendix 3. Specifications and calculations regarding absorption cooling installations

Table A3. 13. Cooling load to be produced and working power of different chillers (double- and single- effect) in Mackmyra production site during the year when the cooling demand is 10% higher than the estimated one COOLING NUMBER OF CHILLERS WORKING % of POWER & CAPACITY [kW] TIME PERIOD max. PRODUCTION power TSA-16NK-81 TSA-16TJ-53 [kW] 15 November-15 March 7,79 428,45 — — 15 March-1 April & 1-15 November 30,54 1679,7 1680 1680 April & 15 October-1 November 40,72 2239,6 2240 2240 1-15 May & 15 September-15 October 58,69 3227,95 3228 1614 1614 15 May-15 June & 15 August-15 September 85,03 4676,65 2338 2338 2338 2338 15 June-15 August 100 5500 2750 2750 1833 1833 1833

Table A3. 14. Cooling power to be supplied to the chillers during the year and necessary cooling towers in Mackmyra production site when the cooling demand is 10% higher than the estimated one COOLING OF CHILLERS [kW] COOLING TOWERS NEEDED TIME PERIOD TSA-16NK-81 TSA-16TJ-53 TSA-16NK-81 TSA-16TJ-53

15 November-15 March — — Capacity: 5710 kW Capacity: 5839 kW Flow: 572,4 m3/h 3 15 March-1 April & 1-15 November 3038,69 4102,86 Flow: 1202,04 m /h ΔTmax. = 8,98 K ΔTmax. = 4,37 K April & 15 October-1 November 4051,59 5470,48 Capacity: 5710 kW Flow: 572,4 m3/h 1-15 May & 15 September-15 October 5838,63 3941,68 3941,68 ΔTmax. = 8,98 K Capacity: 4975 kW 15 May-15 June & 15 August-15 September 4228,84 4228,84 5709,81 5709,81 Flow: 1202,04 m3/h Capacity: 4477 kW 3 ΔTmax. = 3,72 K Flow: 572,4 m /h 15 June-15 August 4974,05 4974,05 4476,51 4476,51 4476,51 ΔTmax. = 7,04 K

125

Appendix 3. Specifications and calculations regarding absorption cooling installations

Table A3. 15. Cooling load to be produced and working power of different chillers (double- and single- effect) in Mackmyra production site during the year when the cooling demand is 10% lower than the estimated one COOLING NUMBER OF CHILLERS WORKING % of POWER & CAPACITY [kW] TIME PERIOD max. PRODUCTION power TSA-16NK-81 TSA-16TJ-53 [kW] 15 November-15 March 7,79 350,55 — — 15 March-1 April & 1-15 November 30,54 1374,3 1374 1374 April & 15 October-1 November 40,72 1832,4 1832 1832 1-15 May & 15 September-15 October 58,69 2641,05 2641 1321 1321 15 May-15 June & 15 August-15 September 85,03 2826,35 3826 1913 1913 15 June-15 August 100 4500 4500 2250 2250

Table A3. 16. Cooling power to be supplied to the chillers during the year and necessary cooling towers in Mackmyra production site when the cooling demand is 10% lower than the estimated one COOLING OF CHILLERS [kW] COOLING TOWERS NEEDED

TIME PERIOD TSA-16NK-81 TSA-16TJ-53 TSA-16NK-81 TSA-16TJ-53

15 November-15 March — — Capacity: 5495 kW 15 March-1 April & 1-15 November 2485,22 3355,55 Flow: 572,4 m3/h April & 15 October-1 November 3313,62 4474,07 Capacity: 8140 kW ΔTmax. = 8,64 K Flow: 1202,04 m3/h 1-15 May & 15 September-15 October 4776,89 3226,12 3226,12 ΔTmax. = 6,09 K Capacity: 5495 kW 15 May-15 June & 15 August-15 September 6920,26 4671,87 4671,87 Flow: 572,4 m3/h 15 June-15 August 8139,35 5494,90 5494,90 ΔTmax. = 8,64 K

126

Appendix 3. Specifications and calculations regarding absorption cooling installations

C. JOHANNES

Table A3. 17. Cooling load to be produced and working power of different chillers in Johannes production site during the year COOLING TOTAL POWER % of max. COOLING NUMBER OF TSA-16LJ-53 PRODUCTION TIME PERIOD power for POWER CHILLERS WORKING FOR Hemlingby PRODUCTION & CAPACITY [kW] HEMLINGBY [kW] [kW] 15 November-15 March 7,79 155,8 1555,8 — 15 March-1 April & 1-15 November 30,54 610,8 2010,8 1006 1006 April & 15 October-1 November 40,72 814,4 2214,4 1107 1107 1-15 May & 15 September-15 October 58,69 1173,8 2573,8 1287 1287 15 May-15 June & 15 August-15 September 85,03 1700,6 3100,6 1551 1551 15 June-15 August 100 2000 3400 1700 1700

NOTE: Cooling demand in Johannes represents the cooling needed for the turbine itself (to cool it down because of friction energy generated by turbine´s axis and generator). Therefore, it is the same all over the year, that is, it does not depend on the time period (outdoor temperature). This way, cooling demand during the year has been estimated for Hemlingby shopping centers and then, 1,4 MW for Johannes have been added up to each of them.

127

Appendix 3. Specifications and calculations regarding absorption cooling installations

Table A3. 18. Cooling power to be supplied to the chillers during the year and necessary cooling towers in Johannes production site COOLING OF COOLING TOWERS TIME PERIOD CHILLERS [kW] NEEDED 15 November-15 March — Capacity: 4150 kW 15 March-1 April & 1-15 November 2455,47 2455,47 Flow: 858,24 m3/h April & 15 October-1 November 2701,99 2701,99 ΔTmax. = 8,70 K 1-15 May & 15 September-15 October 3141,34 3141,34 Capacity: 4150 kW 15 May-15 June & 15 August-15 September 3785,72 3785,72 Flow: 858,24 m3/h 15 June-15 August 4149,40 4149,40 ΔTmax. = 8,70 K

Table A3. 19. Cooling load to be produced and working power of different chillers in Johannes production site when the cooling demand is 10% higher than the estimated one COOLING TOTAL POWER % of max. COOLING NUMBER OF TSA-16LJ-53 PRODUCTION TIME PERIOD power for POWER CHILLERS WORKING FOR Hemlingby PRODUCTION & CAPACITY [kW] HEMLINGBY [kW] [kW] 15 November-15 March 7,79 171,38 1571,38 — 15 March-1 April & 1-15 November 30,54 671,88 2071,88 1036 1036 April & 15 October-1 November 40,72 895,84 2295,84 1148 1148 1-15 May & 15 September-15 October 58,69 1291,18 2691,18 1346 1346 15 May-15 June & 15 August-15 September 85,03 1870,66 3270,66 1635 1635 15 June-15 August 100 2200 3600 1800 1800

128

Appendix 3. Specifications and calculations regarding absorption cooling installations

Table A3. 20. Cooling power to be supplied to the chillers in Johannes production site during the year when the cooling demand is 10% higher than the estimated one COOLING OF COOLING TOWERS TIME PERIOD CHILLERS [kW] NEEDED 15 November-15 March — Capacity: 4394 kW 15 March-1 April & 1-15 November 2528,69 2528,69 Flow: 858,24 m3/h April & 15 October-1 November 2802,07 2802,07 ΔTmax. = 9,22 K 1-15 May & 15 September-15 October 3285,35 3285,35 Capacity: 4394 kW 15 May-15 June & 15 August-15 September 3990,75 3990,75 Flow: 858,24 m3/h 15 June-15 August 4393,48 4393,48 ΔTmax. = 9,22 K

Table A3. 21. Cooling load to be produced and working power of different chillers in Johannes production site when the cooling demand is 10% lower than the estimated one COOLING TOTAL POWER % of max. COOLING NUMBER OF TSA-16LJ-53 PRODUCTION TIME PERIOD power for POWER CHILLERS WORKING FOR Hemlingby PRODUCTION & CAPACITY [kW] HEMLINGBY [kW] [kW] 15 November-15 March 7,79 140,22 1540,22 — 15 March-1 April & 1-15 November 30,54 549,72 1949,72 975 975 April & 15 October-1 November 40,72 732,96 2132,96 1066 1066 1-15 May & 15 September-15 October 58,69 1056,42 2456,42 1228 1228 15 May-15 June & 15 August-15 September 85,03 1530,54 2930,57 1465 1465 15 June-15 August 100 1800 3200 1600 1600

129

Appendix 3. Specifications and calculations regarding absorption cooling installations

Table A3. 22. Cooling power to be supplied to the chillers in Johannes production site during the year when the cooling demand is 10% lower than the estimated one COOLING OF COOLING TOWERS TIME PERIOD CHILLERS [kW] NEEDED 15 November-15 March — Capacity: 3906 kW 15 March-1 April & 1-15 November 2379,80 2379,80 Flow: 858,24 m3/h April & 15 October-1 November 2601,92 2601,92 ΔTmax. = 8,19 K 1-15 May & 15 September-15 October 2997,33 2997,33 Capacity: 3906 kW 15 May-15 June & 15 August-15 3575,81 3575,81 Flow: 858,24 m3/h September ΔT = 8,19 K 15 June-15 August 3905,32 3905,32 max.

130

Appendix 3. Specifications and calculations regarding absorption cooling installations

A3.2. THE REST OF EQUIPMENTS

Table A3. 23. Required cooling towers and heat exchangers´ technical data HEAT EXCHANGERS HEAT EXCHANGERS (+FILTER) PRODUCTION SITE COOLING TOWERS (+FILTER) -chillers´cooling down- -free cooling- S121-IS10-502-TMTL47-LIQUIDE (Sondex) 16NK-81 — Flow: 339 kg/s chillers Capacity: 8505 kW TL10-BFG (Alfa Laval) LEAF FILTER: BSG350/1,0P (Bernoulli) Flow: 38,7 l/s Capacity: 895,0 kW 16TJ-53 MX25-MFMS (Alfa Laval) — Flow: 241,4 l/s chillers Capacity: 6010 kW OCT09HB05-5-90 (Vestas Aircoil) Flow: 1221 m3/h. Evaporation: 10,9 m3/h 16NK-81 Capacity: 5988 kW — chillers Number of fans: 5 Air flow/fan: 30,41 m3/s. Rotation speed: 439 rpm TL10-BFG (Alfa Laval) MACKMYRA Electric power supply/fan: 6,1 kW Flow: 16,8 l/s OCT09HB03-3-120 (Vestas Aircoil) Tin = 12,2ºC. Tout = 6,7 ºC Flow: 573 m3/h. Evaporation: 7,7 m3/h 16TJ-53 Capacity: 8499 kW — chillers Number of fans: 3 Air flow/fan: 21,29 m3/s. Rotation speed: 340 rpm Electric power supply/fan: 5,14 kW OCT09HB02-2-120 (Vestas Aircoil) Flow: 429 m3/h. Evaporation: 5,7 m3/h 16LJ-53 Capacity: 4483 kW JOHANNES — — chillers Number of fans: 2 Air flow/fan: 23,91 m3/s. Rotation speed: 531 rpm Electric power supply/fan: 7,3 kW

131

Appendix 3. Specifications and calculations regarding absorption cooling installations

NOTE 1: Power of cooling towers is determined by fan´s air flow (cooling water flow is constant), of which relation can be considered to be linear. For calculating power of fans (electricity supply), following equations are used:

q1/q2 =n1/n2 3 P1/P2 = (n1/n2)

where: - q: fan´s air flow - n: fan´s rotation speed (rpm) - P: power

NOTE 2: Size of equipments - LEAF. Same heat exchangers have been considered for the three cases since differences between the needed capacities are not so large and, in addition, those equipments can work at 10% higher capacity than the specified one.

- MACKMYRA. The highest capacity between required cooling equipments have been approximately taking into consideration to make the decision about the cooling towers to be introduced. They are valid for all cases as the flow is constant, so they will work according to the needed cooling capacity (they are too big in some cases but data about more adequate towers could not be obtained).

- JOHANNES. Cooling tower has been choosen so that it can cover the cooling demand in the three cases, as the differences are not so large.

132

Appendix 4. MAPS OF CUSTOMERS AND DISTANCES FROM THE PRODUCTION SITES

A. CITY CENTER (LEAF)

Figure A4. 1. Map of the city center with the main pipe that leaves LEAF production site and its length

133

Appendix 4. Plans of customers and distances from the production sites

It has been followed the same way for the main pipe as in the refrigerant compression cooling project, since the production site and customers are the same and, in addition, as necessary remarks for this decision have been already taken into account.

134

Appendix 4. Plans of customers and distances from the production sites

B. KUNGSBÄCK AREA (MACKMYRA)

Figure A4. 2. Map with the customers, pipes and distances for Mackmyra production site

135

Appendix 4. Plans of customers and distances from the production sites

The pipe which arrives at hospital from Mackmyra would need to go through the technologic park, since it is also a customer. This way, it has been decided to follow the direction of roads and the existing district heating installation.

136

Appendix 4. Plans of customers and distances from the production sites

C. JOHANNESBERGSVÄGEN AREA (JOHANNES)

HEMLINGBY SHOPPING CENTERS

Johannes

Figure A4. 3. Map with the customers for Johannes production site, pipe and its length

137

Appendix 4. Plans of customers and distances from the production sites

The absorption plant at Johannes would be used to fulfil the cooling demand of the existing Hemlingby shopping center and buildings which are under construction now, with a total cooling floor area of 35 000 m2 (see Figure A4. 4.). The extension is expected to be finished by this summer (2009).

Figure A4. 4. Map of the shopping centers under construction in Hemlingby

For this reason, the main distribution pipe is planning to be between all these buildings. Once the pipe would leave the constructed area, it would go through the forest, since its digging is cheaper than road´s, and cross E4 highway taking the advantage that it already exists a tunnel there. Thereafter, it would reach the production plant as drawn because of the possibility of future customers over there. Next Figure A4. 5. shows the future plan of the municipality of building a new area close to Johannes CHP plant.

138

Appendix 4. Plans of customers and distances from the production sites

Figure A4. 5. Map of the future residential area close to Johannes plant

139

Appendix 5. CALCULATIONS ABOUT DIMENSIONS OF PIPES, DISTRIBUTION PUMPS AND THEIR COSTS

A5.1. DIMENSIONING

Table A5. 1. Dimensioning of pipes and pressure drop (part I) COOLING VOLUMETRIC PRODUCTION DISTANCE MASS FLOW PIPES CUSTOMER DEMAND FLOW SITE [m] [kg/s] [kW] [m3/h] LEAF LEAF CITY CENTER 9000 1370 214,29 771,43 HOSPITAL 1700 UNIVERSITY 1800 Mackmyra I TECHNOLOGIC 1000 PARK TOTAL 4500 500 107,14 385,71 MACKMYRA Mackmyra II UNIVERSITY 1800 310 42,86 154,29

HOSPITAL 1700 TECHNOLOGIC Mackmyra III 1000 PARK TOTAL 2700 1890 64,29 231,43 HEMLINGBY JOHANNES Johannes SHOPPING 2000 1775 47,62 171,43 CENTERS NOTE: Mass flow: P [kW] = m [kg/s] * Cp [kJ/kg K] * ∆T [K] → m = P/Cp/∆T

140

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

Table A5. 2. Dimensioning of pipes and pressure drop (part II) INTERNAL CROSS PRESSURE PRESSURE FOR PRODUCTION DIAMETER RESISTANCE PIPES CUSTOMER SECTION OF LOSS for DISTRIBUTION SITE OF THE PIPE [Pa/m] THE PIPE [m2] each pipe [Pa] PUMP [Pa] 38 [mm] LEAF LEAF CITY CENTER 0,11 369,44 65 89050 328100 HOSPITAL UNIVERSITY Mackmyra I TECHNOLOGIC PARK

TOTAL 0,05 261,24 100 50000 25000

MACKMYRA Mackmyra II UNIVERSITY 0,02 165,22 175 54250 258500

HOSPITAL TECHNOLOGIC Mackmyra III PARK TOTAL 0,032 202,35 130 245700 641400 HEMLINGBY JOHANNES Johannes SHOPPING 0,02 174,16 160 284000 718000 CENTERS NOTES (in the next page):

38 As the flow passes through pipes and other components in the system, the pressure decreases. Thus, it is needed a pressure difference in the system which is generated in the pump and which is progressively dissipated by pressure losses in the distribution system with increasing distance from the pump. This is shown in schematic Figure A5. 2.

141

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

NOTES: - Diameter of pipes: ø = 2 √(A/π) - The cross section of pipes has been calculated for a velocity of water flow of 2 m/s (it is usually between 1 and 3 m/s for large pipes), for considering it the most suitable (Greger Berglund). - The resistances have been calculated by using a SBI nomogram that can be seen in the following page (Figure A5. 1.). - Pressure increase that is needed (distribution pump) has been calculated considering that there is a pressure drop of 150 kPa in the customer site (Greger Berglund), although it is usually enough with 30-50 kPa –safety margin-.

142

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

Figure A5. 1. SBI monogram showing the parameters of the different pipes

143

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

Figure A5. 2. Differential pressures in a direct return distribution system with one terminal unit

Distribution losses could be calculated as following:

(Source: lecture of Energy Systems, HIG, by Heimo Zeinko)

Nevertheless, they are not taken into consideration because of being very small. There is only a temperature difference of 4ºC between the water that goes through pipes and outside, so the resistances are therefore almost zero.

144

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

Going back to the diameter of pipes, outer diameters have been obtained by using the following Table A5. 3. once internal diameters (see Table A5. 2.) have been calculated.

Table A5. 3. PE Pressure Pipes for water supply: EN 12201, ISO 4427 (Source: PE Pressure Pipe Systems brochure)

145

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

Finally, Table A5. 4. shows the dimension of pipes needed.

Table A5. 4. Data of the pipes needed 39 PIPES MATERIAL dn [mm] LEAF KWH PE, PN10 40 450 Mackmyra I KWH PE, PN10 315 Mackmyra II KWH PE, PN10 200 Mackmyra III KWH PE, PN10 250 Johannes KWH PE, PN10 200

A5.2. COSTS

A. DIGGING FOR PIPES AND TOTAL COSTS

The distribution system in ground looks like it is shown in Figure A5. 3.. Ground is dug and two pipes, forward and return ones, are introduced keeping the distances (Greger Berglund) that can be observed in the figure. The hole is filled with sand.

Figure A5. 3. Piping excavation section

39 dn: nominal outer diameter 40 PN: nominal pressure. Maximum pressure for plastic pipes is 10 bar (PN10).

146

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

The values of parameters B and C from Figure A5. 3. depend on the outer diameter, dn. Those are gathered in Table A5. 5.

Table A5. 5. Values of parameters C and B for the required dn (Source: Greger Berglund, Gävle Energi AB) dn [mm] C [mm] B [mm] 200 400 1000 250 450 1100 315 525 1250

NOTE: data for dn = 315 mm was missing, so the values have been interpolated from the values of the original data and rounded off.

When pipes are going through water (as appropiate for LEAF), the installation is totally different. Pipes are placed in the bottom of the river (or sea, in other cases), keeping a distance of described C value between them. It would be

750 mm for LEAF pipes (dn = 450).

Next, costs of the main distribution system are shown, Table A5. 6., without taking into account the pumps.

Table A5. 6. Total cost of the pipes (Source: Greger Berglund, Gävle Energi AB, and Anders Kedbrant, SWECO) COST SINGLE PIPE PIPE [SEK/m] MACKMYRA I 3408 MACKMYRA II 2698 COUNTRY SIDE MACKMYRA III 3053 JOHANNES 2698 WATER –river- LEAF 2500

Cost for pipes in countryside can be splitted up in its different components. This way, the following graph in Figure A5. 4. shows it in percentages.

147

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

Figure A5. 4. Distribution system cost split up in its components and their contribution to the total cost

Finally, total costs of the distribution system except for the pumps can be calculated:

Table A5. 7. Calculation of the pipes´ costs COST TOTAL PRODUCTION DISTANCE COST PIPE PER PIPE COST SITE [m] [SEK/m] [SEK] [SEK] LEAF LEAF 1 370 2500 3 425 000 6 850 000 Mackmyra I 500 3 408 1 704 000 3 408 000

Mackmyra II 310 2 698 836 380 1 672 760

MACKMYRA Mackmyra III 1 890 3 053 5 770 170 11 540 340 TOTAL 16 621 100 JOHANNES Johannes 1 775 2 698 4 788 950 9 577 900

148

Appendix 5. Calculations about dimensions of pipes, distribution pumps and their costs

B. PUMPS

Table A5. 8. Needed distribution pumps and their cost (Source: Zander & Ingeström AB) MAX. PRODUCTION Q 41 P POWER PRICE PUMP TYPE SITE [m3/h] [kPa] CONS. [SEK] [kW] KENFLO centrifugal LEAF 771,43 328,1 77,4 110 000 pump, KPS 30-250 KENFLO centrifugal MACKMYRA 317,14 250 27,5 62 000 pump, ISO 200x150-315 KENFLO centrifugal JOHANNES 171,43 718 44,5 69 000 pump, ISO 100x65-250

NOTE: Electric power consumption cannot be calculated in accordance with pumps´ working power during the year as their design curves are unkown. Thus, it has been assumed that they work the same way as pumps from compression refrigerant cooling project and therefore considered that they are working at their maximum capacity all over the year except for winter time and for when chillers are shut down, when they work at 30% of the maximum capacity.

41 Q: volumetric flow

149

Appendix 6. FALUN COOLING PROJECT: A REFERENCE

A6.1. INSTALLATION

Figure A6. 1. Draft of the whole cooling installation in Falun (Source: Daniel Widman, Falu Energi & Vatten AB) 150

Appendix 6. Falun cooling project: a reference

Table A6. 1. Reference specifications about absorption chiller in Falun (Source: Carrier-Sanyo)

There are additional remarkable devices in the installation, such as: - A compression chiller of 1290 kW. It has two functions: to keep cooling in reserve and to fulfil the demand in periods of higher loads. - Two BAC (Baltimore Air Coil) VXT 470 cooling towers. - Grundfos pumps. Distribution pumps: FK-P01 (50 kW).

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Appendix 6. Falun cooling project: a reference

A6.2. TOTAL COSTS

Table A6. 2. Investment costs for different installations in Falun COST OF THE WHOLE INSTALLATION [SEK] 10 000 000 COST OF THE COMPRESSION COOLING MACHINE [SEK] 1 500 000 COST OF THE ABSORPTION CHILLER [SEK] 2 700 000 COST OF THE COOLING TOWERS [SEK] 2 * 675 000 COST OF THE DISTRIBUTION PUMPS [SEK] 100 000

Like this, the COST of the INSTALLATION without distribution pumps, chillers and cooling towers is 1 450 000 SEK.

Maintenance costs are very low, so they are therefore not taken into account. With regards to operational costs, they are calculated as sum of electric power needed and water for cooling towers (it is assumed that steam is free). This way, it is needed to assess costs for 250 kW plus 50 kW per each distribution pump of electricity (≈1 SEK/kWh) and 10 m3/h of water (≈4 SEK/ m3).

Total electric consumption of the whole installation is made up of:

Table A6. 3. Input electric power in Falun installations TOTAL 250 kW POWER SUPPLY TO THE ABSORPTION CHILLER 5,84 kW 42 POWER SUPPLY TO THE COOLING TOWERS 2 * 30,0 kW (there are 2 fans in each cooling tower) POWER NEEDED IN THE REST OF THE INSTALLATION 184,16 kW

NOTE: Compressor chiller´s input power at its maximum capacity is 300 kW. Nevertheless, it is not included as it is seldom working.

42 P = 7,3 kVA * 0,8 (power factor that most generators use) = 5,84 kW

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Appendix 7. EXTRA INFORMATION ABOUT JOHANNES POWER PLANT

Johannes plant has a biofueled steam boiler, where there are mainly burnt bark, forest residues and waste wood43. Nonetheless, it is needed oil to start up the plant (which takes between 12 and 18 hours) and unfortunately, this fuel has to be also sometimes used because of technical problems.

Next, basic scheme of the plant is shown in Figure A7. 1. for explaining how it operates thereafter.

8 12 11

5 9 10 6 7

1. FUEL INTAKE 2. SIEVING (fuel mixer) 4 3. FUEL STORAGE 3 4. CONVEYOR BELT FOR BIOFUEL UP TO THE BOILER 5. STEAM BOILER 6. DIRECT CONDENSER 7. TURBINE 13 8. VESSEL ACCUMULATORS 14 9. ELECTROSTATIC PRECIPITATOR 2 10. FLUE GAS CONDENSER (FGC) 11. CHIMNEY STACK 12. CONTROL ROOM 13. OIL TANK 14. AMMONIA TANK 1 Figure A7. 1. Scheme of Johannes CHP plant (Source: Gävle Energi AB)

The different types of biofuel, which are stored according to their composition in different piles outside (see Figure A7. 2.), are mixed and carried

43 The blending changes frecuently, which depends on the availability of different fuels, costs and so forth.

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Appendix 7. Extra information about Johannes power plant

into a silo (sieving). Afterwards, the fuel mixture is put on a fuel storage building. This place has a fuel capacity of a weekend production, since there is nobody working on fulfilling it during this period.

Figure A7. 2. Fuel storage 44 and conveyor belt carrying biofuel to the boiler at Johannes

The biofuel mixture is transported to the boiler using a conveyor belt (which gets in a fuel container) as means of transport (see Figure A7. 2.), where it is then burned. The steam boiler, which scheme is shown in Figure A7. 3., is a Bubble Fluidized Bed (BFB) with a maximum capacity of 77 MW.

Biofuel enters the boiler through two intakes together with some air (it is injected in order to avoid flames go into fuel silo). Primary air goes in the bottom, where a sand bed is. There, solid fuel is suspended on upward-blowing jets of air and a turbulent mixing is achieved. As a result, more effective combustion and heat transfer take place.

The combustion heats water, which is coverted into superheated steam at high and constant pressure. The steam leaving the boiler goes thereafter to the turbine.

44 This picture was taken the 24th of March of 2009, when it was still winter. Despite the snow and cold weather, biofuel keeps well since it is warm inside due to reactions (aerobic decomposition of organic matter) that take place in there.

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Appendix 7. Extra information about Johannes power plant

29 kg/s 94 bar

Figure A7. 3. Bubble Fluidized Bed (BFB) boiler of Johannes CHP plant (Source: Gävle Energi AB)

The turbine called Olga was installed in 2005, which means that there was previously a direct condenser instead that was used to cool down the steam by means of district heating return water (it is still in there in case of a breakdown or higher heating demands). It is a backpressure turbine, model Siemens SST-600, which works in two steps and has a power output capacity of 22 MW (see Figure A7. 4. and left side of Figure A7. 5.), where electricity is produced by expanding and cooling the steam.

The exhaust steam leaving the turbine is then condensed in two heat exchangers (see right side of Figure A7. 5.) and the water that extracts heat from the steam goes to the supply pipe of the district heating network. When heat supply is higher than the demand, hot water is stored, what there are two heat accumulators for, and this way, it is delivered when the demand is higher (compensation of load variations).

Characteristics of obtained electricity and water for district heating are gathered in Table A7. 1.

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Appendix 7. Extra information about Johannes power plant

Turbine

Generator

Heat exchangers

Figure A7. 4. Illustrative drawing of Olga turbine and components (Source: Gävle Energi AB)

Figure A7. 5. Olga turbine on the left side and heat exchangers on the right side. Johannes CHP plant

Table A7. 1. Characteristics of the obtained outputs at Johannes ELECTRICITY Power 23MW Generator voltage 11 kV DISTRICT HEATING Power 50 MW Forward temperature 96 ºC Return temperature 67 ºC

Exhaust gases leaving the boiler go through an electrostatic precipitator in order to eliminate particulate matter and after that heat is extracted in a flue-gas

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Appendix 7. Extra information about Johannes power plant

condensation system (see Figure A7. 6. and for more specified information, Figure A7. 7.). This waste heat is also used in the district heating network and sand-ashes, together with the sand extracted from the bottom of the boiler and cleaned in a rotational sieve, are recycled for reutilizing them in the boiler.

Figure A7. 6. Schematic of the FGC at Johannes (Source: Gävle Energi AB)

Figure A7. 7. Detailed scheme of the condensate treatment plant at Johannes (Source: Gävle Energi AB)

Moreover, there is a water purification system where ultrapure water (conductivity < 20 μS/m) is obtained as it is required for the boiler. The technology is called EDI (electrodeionisation), which combines ion exchange and membrane filtering.

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