Downloaded from orbit.dtu.dk on: Sep 27, 2021 Solar energy: state of the art Furbo, Simon; Shah, Louise Jivan; Jordan, Ulrike Publication date: 2003 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Furbo, S., Shah, L. J., & Jordan, U. (2003). Solar energy: state of the art. BYG Sagsrapport No. SR 03-14 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Editors: Simon Furbo Louise Jivan Shah Ulrike Jordan Solar Energy State of the art DANMARKS TEKNISKE UNIVERSITET Internal Report BYG·DTU SR-03-14 2003 ISSN 1601 - 8605 Solar Energy State of the art Editors: Simon Furbo Louise Jivan Shah Ulrike Jordan Department of Civil Engineering DTU-bygning 118 2800 Kgs. Lyngby http://www.byg.dtu.dk 2003 PREFACE In June 2003 the Ph.D. course Solar Heating was carried out at Department of Civil Engineering, Technical University of Denmark. The participants worked out state-of-the-art reports on 6 selected solar topics. This report is a collection of the reports. The course was sponsored by Nordic Energy Research. July 2003 CONTENTS Solar Combisystems Helena Gajbert, Lund Technical University, Sweden & Frank Fiedler, Solar Energy Research Center SERC, Högskolan Dalarna, Sweden…….………………………………………………………… Page 1-25 Thermal Storage for Small Solar Heating Systems Søren Knudsen, Department of Civil Engineering, Technical University of Denmark, Denmark & Mike Dennis, Centre for Sustainable Energy Systems, Australian National University, Australia…………………………………………………………...... Page 1-25 Solar Collector Materials M. Reza Nejati, Energy Systems Engineering Group, Department of Mechanical Engineering, K.N. Toosi University of Technology, Iran & V. Fathollahi, Center for Renewable Energy Research and Application CRERA, Iran…………………………………………... Page 1-10 Solar Cooling Wimolsiri Pridasawas, Royal Institute of Technology, Sweden and Teclemariam Nemariam, Royal Institute of Technology, Sweden…. Page 1-31 Solar Thermal Technologies for Seawater Desalination Jenny Lindblom, Renewable Energy Systems, Luleå University of Technology, Sweden………………………………………………... Page 1-17 Review of the State of the Art: Solar Radiation Measurement and Modeling Pongsak Chaisuparasmikul, College of Architecture, Illinois Institute of Technology, USA & Thomas Bache Andersen, Department of Civil Engineering, Technical University of Denmark, Denmark…………………………………………………………….. Page 1-19 Ph.D. Course SOLAR HEATING DEPARTMENT OF CIVIL ENGINEERING TECHNICAL UNIVERSITY OF DENMARK (DTU) SOLAR COMBISYSTEMS A STATE OF THE ART REPORT HELENA GAJBERT & FRANK FIEDLER Lund Technical University Solar Energy Research Center SERC, Högskolan Dalarna JULY 04, 2003 1 TABLE OF CONTENTS 1 Introduction ........................................................................................................................ 3 2 Background ........................................................................................................................ 4 3 Latest research on improvement of combisystems ............................................................ 8 3.1 Improvements from Task 26 ...................................................................................... 8 3.3 New storage medium................................................................................................ 10 3.4 Improved storage insulation..................................................................................... 11 3.5 Collectors adapted for seasonal load........................................................................ 11 3.6 Compact systems...................................................................................................... 14 3.7 Advanced control strategy for solar combisystems.................................................. 16 4 Evaluation methods for combisystems............................................................................. 18 4.1 The CTSS method .................................................................................................... 18 4.2 The DC test method.................................................................................................. 18 4.3 The CCT method...................................................................................................... 20 4.4 The characterization tool FSC.................................................................................. 20 4.5 Calculation model for assessment of reliability in solar combisystems................... 21 5 Summary .......................................................................................................................... 23 Literature .................................................................................................................................. 24 2 1 Introduction Due to the increasing concentration of greenhouse gases and climate changes, the need for renewable energy sources is greater than ever. This has now attracted attention from the European Commission that has set up targets to increase the share of renewable energy supply in Europe in order to reduce greenhouse gas emissions. By using solar thermal systems, a significant part of the space heating and hot water demand can be covered. In order to increase the market for solar systems, technical improvements of the systems has to be made, so that the systems can be more cost efficient. By using solar combisystems that deliver heat for both hot water and for space heating, a greater part of the total energy demand can be covered by solar energy. The share of solar combisystems has increased lately in many countries. In the middle and northern European countries the heat demand for space heating is still significantly higher than for hot water only. Therefore, the use of combisystems could significantly reduce the use of fossil fuel in these countries. Within this report the newest developments of solar combisystems in terms of technical improvements and trends are investigated and discussed in order to provide a general overview of the situation of solar combisystems today. As sources for this investigation served articles from the Solar World Congress 2003 in Gothenburg as well as reports from the IEA task 26 “Solar Combisystems”. Solar combisystems in the context of this report are systems for delivering hot water and space heating for residential buildings, mostly for detached houses built for one or two families. Larger systems e.g. systems with seasonal heat storage or combination of heat pumps and solar collectors are not investigated. Within the framework of task 26 typical industrial made solar combisystems in the participant countries have been identified and systematically investigated in terms of their design and performance. 3 2 Background Today about 82% of the world’s primary-energy requirements are covered by coal, natural gas, oil and uranium. Approximately 12% comes from biomass and 6% from hydroelectric power. A reduction of greenhouse gases throughout the world of about 50 % is required in the next 50-100 years, according to many experts. In order to achieve this, a reduction of greenhouse gas emissions of approximately 90% per capita in the industrial countries, will be necessary. If we shall be able to change our energy supply system and reduce greenhouse gases, we need to use renewable energy sources, and solar energy is one of the most environmentally safe energy sources. The European Commission has set up goals, described in the White Paper ”Energy for the future, renewable sources of energy”, to increase the market share of renewable energy sources from 6%, as it is today, to 12% by the year 2010 [17]. The energy consumption in the building sector represents around 40% of all end energy consumption in the EU, of which 75% is required for hot water and space heating. Until 2000 only around 0.11% of the total requirement for hot water and space heating are covered by solar thermal systems. According to the White Paper, this share should be increased to 1.18% until 2010 [16]. Experts have estimated that an annual increase of 20% of installed collector area will be necessary in order to accomplish this goal. Today the installed collector area in the EU is approximately 18 million m2 (of which approximately 7 million m2 are collectors in combisystems) and by the year 2010 100 million m2 would have to be installed (20 million m2 for combisystems). In order to accomplish these goals, the solar heating technologies need to be further developed [17]. 100 90 Total collector area 80 s e 70 r Share of combisystems t e 60 m e r 50 qua 40 on s i l l i 30 m 20 10 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Figure 1. The predicted area of solar collectors that needs to be installed within the EU until 2010 in order to accomplish the goals, according to many