DOCSLIB.ORG

Plate-And-Frame Free Cooling

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Plate-And-Frame Free Cooling CDS-PRM001-EN_new.book Page 43 Tuesday, March 16, 2010 3:03 PM Plate-and-frame free cooling One way to reduce the energy consumption of a chilled-water plant is to precool the water in the chilled-water loop before it Plate-and-frame enters the evaporator. This can be accomplished by piping a heat exchangers are plate-and-frame heat exchanger into the chilled-water and sometimes referred to as condenser-water loops. Using the piping arrangement shown in waterside economizers. Figure 3–9, free cooling and mechanical cooling occur simultaneously. (Plate-and-frame free cooling can be achieved with other piping arrangements, depending on the operating characteristics desired.) Figure 3–9 Chilled-water plant with plate-and-frame free cooling When the ambient wet-bulb temperature is low enough, the heat exchanger transfers heat from the chilled water returning to the evaporator to the condenser water returning from the cooling tower. Precooling the chilled water before it enters the evaporator lessens the cooling burden, reducing the energy that the chiller uses. Application considerations ■ Adding a heat exchanger to provide free cooling increases the initial cost of the system. The additional pressure loss also raises pumping costs. ■ The ambient wet-bulb temperature determines the free-cooling capacity of the heat exchanger—cooling capacity diminishes as the ambient wet-bulb temperature rises. Free cooling is only CDS-PRM001-EN • TRACE 700 User’s Manual Cooling and Heating Plants 3–43 Plate-and-frame free cooling CDS-PRM001-EN_new.book Page 44 Tuesday, March 16, 2010 3:03 PM available when the ambient wet-bulb (AWB) temperature is less than the design return chilled-water (DRCW) temperature plus the heat exchanger approach (HEA) temperature, that is, AWB DRCW+ HEA ■ The cooling tower must be designed for winter operation. ■ Water entering the condenser must be maintained within the temperature limits specified by the chiller manufacturer. Related reading ■ Multiple-Chiller-System Design and Control Applications Engineering Manual (Trane literature number SYS-APM001-EN) ■ Chilled Water Systems Air Conditioning Clinic, one of the systems series (Trane literature number TRG-TRC016-EN) ■ “A New Era of Free Cooling,” Engineers Newsletter (volume 20, number 3) Sample scenario A chilled-water plant includes a three-stage centrifugal chiller and a plate-and-frame heat exchanger that has a 3°F approach. The following illustrations demonstrate how to model this plant. Cooling-equipment definitions in the TRACE 700 library include an approach temperature for a plate-and- frame heat exchanger—the default is 3°F. To model a different approach To change the approach temperature, use the Library/ temperature, choose a plate- Template Editors program to and-frame type here… copy and modify an existing piece of cooling equipment. Note: TRACE 700 assumes that the capacity of the heat exchanger equals the cooling capacity of the chiller to which …then type the new approach it is assigned. temperature here. 3–44 Cooling and Heating Plants TRACE 700 User’s Manual • CDS-PRM001-EN Plate-and-frame free cooling CDS-PRM001-EN_new.book Page 45 Tuesday, March 16, 2010 3:03 PM To model a cooling plant that includes a plate-and- frame heat exchanger: 1 Select the desired equipment type. For this example, pick one of the centrifugal chillers from the water-cooled chiller category. 2 Enter the full-load consumption for each pump. 3 Click Controls and choose Plate & frame series uses the one of the plate-and-frame heat exchanger to supplement options as the free cooling mechanical cooling. Plate & frame uses the heat type. exchanger instead of mechanical For a cooling plant with cooling, but only if ambient multiple chillers, be sure to conditions permit. The heat specify the free-cooling exchanger only operates if it can option for each chiller. satisfy the entire cooling load. CDS-PRM001-EN • TRACE 700 User’s Manual Cooling and Heating Plants 3–45 Plate-and-frame free cooling CDS-PRM001-EN_new.book Page 46 Tuesday, March 16, 2010 3:03 PM Refrigerant-migration free cooling As the name implies, refrigerant-migration free cooling is based on the principle that refrigerant migrates to the coldest point in a refrigeration circuit. Under favorable conditions, this energy- saving option for centrifugal chillers can provide up to 40 percent of the design cooling capacity of the chiller. When condenser water returning from the cooling tower is colder than the water in the chilled-water loop, as depicted in Figure 3–10, the refrigerant pressure in the condenser is less than that in the evaporator. This difference in pressure drives refrigerant vapor from the evaporator to the condenser, where it liquefies. With the help of gravity, the liquid refrigerant flows back to the evaporator. The non-mechanical refrigeration cycle is sustained, providing free cooling, as long as the differential refrigerant pressure is sufficient to drive vapor from the evaporator to the condenser. Figure 3–10 Refrigerant-migration free cooling Application considerations ■ Mechanical cooling and refrigerant-migration free cooling cannot occur simultaneously. This type of free cooling can only be used if the cooling capacity of the tower water is sufficient to meet the entire building load. 3–46 Cooling and Heating Plants TRACE 700 User’s Manual • CDS-PRM001-EN Refrigerant-migration free cooling CDS-PRM001-EN_new.book Page 47 Tuesday, March 16, 2010 3:03 PM ■ Little, if any, free-cooling capacity is available when the ambient wet-bulb temperature exceeds 50°F. ■ Unlike the compressor (which is off), accessories such as pumps and cooling-tower fans continue to operate in the conventional manner during the free-cooling mode. ■ The cooling tower must be designed for winter operation. Related reading ■ Chilled Water Systems Air Conditioning Clinic, one of the systems series (Trane literature number TRG-TRC016-EN) Sample scenario A water-cooled centrifugal chiller is equipped for refrigerant- migration free cooling. When ambient conditions permit, free cooling satisfies up to 40 percent of the design capacity of the chiller. To model a chiller with refrigerant-migration free cooling: 1 Add the appropriate equipment category to the cooling plant. For this example, select water- cooled chiller. (This is equivalent to dragging an equipment icon to a plant on the Configuration tab.) 2 Replace the default equipment tag with a more descriptive name, if desired. 3 Select the desired equipment type and full- load consumption for each If refrigerant-migration pump. free cooling cannot satisfy the entire load, 4 Click Controls and choose then mechanical cooling the appropriate option from is used instead. the list of free cooling types (in this case, refrigerant migration). CDS-PRM001-EN • TRACE 700 User’s Manual Cooling and Heating Plants 3–47 Refrigerant-migration free cooling CDS-PRM001-EN_new.book Page 48 Tuesday, March 16, 2010 3:03 PM Strainer-cycle free cooling Like other methods of free cooling for chillers, strainer-cycle free cooling acts as a waterside economizer that reduces the amount of energy consumed to produce chilled water. In this case, the source of cooling is condenser water returning from the cooling tower. Figure 3–11 illustrates a typical strainer-cycle piping arrangement that provides free cooling. When the ambient wet-bulb temperature is cold enough, the tower water is valved around the chiller and directly into the chilled-water loop. A filter is positioned upstream of the valve to strain the condenser water before it enters the chilled-water loop, resulting in the name given to this method of free cooling. Figure 3–11 Piping arrangement for strainer-cycle free cooling Application considerations ■ Pumping cooling-tower water throughout the entire chilled-water loop increases the risk of corrosion and fouling. Water treatment, though costly, can help mitigate this risk. ■ Free cooling is only available if the leaving-tower water can satisfy the entire cooling load, limiting the effectiveness of this option. Ambient wet-bulb temperature determines the amount of free- cooling capacity available from the strainer cycle—cooling capacity diminishes as the ambient wet-bulb temperature rises. 3–48 Cooling and Heating Plants TRACE 700 User’s Manual • CDS-PRM001-EN Strainer-cycle free cooling CDS-PRM001-EN_new.book Page 49 Tuesday, March 16, 2010 3:03 PM ■ The cooling tower must be designed for winter operation. Sample scenario A chilled-water plant, which includes a water-cooled centrifugal chiller, is piped to provide strainer-cycle free cooling. After adding a water- cooled chiller to the cooling plant: 1 Choose the appropriate equipment type (a centrifugal chiller for this example). 2 Specify the full-load consumption for each pump. 3 Click Controls and choose strainer cycle from the list of free cooling types. If strainer-cycle free cooling Strainer-cycle free cooling cannot satisfy the entire occurs at the plant level. If load, then mechanical the cooling plant includes cooling is used instead. multiple chillers, repeat this step for each chiller. CDS-PRM001-EN • TRACE 700 User’s Manual Cooling and Heating Plants 3–49 Strainer-cycle free cooling.
Load more

Recommended publications
  • Page 1 OPTIMAL ENERGY MANAGEMENT of HVAC
    Page 1 OPTIMAL ENERGY MANAGEMENT OF HVAC SYSTEMS BY USING EVOLUTIONARY ALGORITHM Session Number: CIB T2S5 Authors Fong K F, BEng, MSc, CEng, MCIBSE, MHKIE, MASHRAE Hanby V I, BSc, PhD, CEng, MInstE, MCIBSE Chow T T, PhD, CEng, MIMechE, MCIBSE, FHKIE, MASHRAE Abstract The available plant and energy simulation packages become robust and user-friendly, and this is the major reason that they are so popular even in the consultancy fields in these few years. In fact, these plant and energy simulation packages can be widely adopted in studying different alternatives of the operation of HVAC and building services systems. Since there are many parameters involved in different equipment and systems, one of the useful areas of studies is to optimize the essential parameters in order to provide a satisfactory solution for design or operation in terms of efficient and effective facilities management. Therefore in this paper, the simulation-optimization approach is proposed for effective energy management of HVAC systems. Due to the complexity of the HVAC systems, which commonly include the refrigeration, water and air side systems, it is necessary to suggest optimal conditions for different operation according to the dynamic cooling load requirements throughout a year. A simulation-EA coupling suite has been developed by using the metaheuristic skill, and the evolutionary algorithm can be effectively used to handle the discrete, non-linear and highly constrained characteristics of the typical HVAC and building services optimization problems. The effectiveness of this simulation-EA coupling suite has been demonstrated through the establishment of the monthly optimal reset scheme of the chilled water supply temperature of a local central chiller plant.
    [Show full text]
  • Ene04 Low Carbon Design Low and Zero Carbon Technologies
    Ene04 Low carbon design Low and zero carbon technologies Actions: i. Implement LZC (low and zero carbon) technologies in-line with the LZC feasibility study ii. Implement passive design measures and free cooling technologies in line with the previous analysis undertaken Recognised local LZC technologies Technologies eligible to contribute to achieving the criteria must produce energy from renewable sources and meet all other ancillary requirements as defined by Directive 2009/28/EC. Local does not have to mean on site – community schemes near to the site can be used as a way of demonstrating compliance. The following requirements must also be met: 1. There must be a direct supply of energy produced to the building under assessment. 2. Technologies under 50 kWe or 45 kWth must be certified by a Microgeneration Certification Scheme (MCS), or equivalent, and installed by MCS (or equivalent) certified installers. 3. Combined heat and power (CHP) schemes above 50 kWe must be certified under the CHPQA standard. CHP schemes fuelled by mains gas are eligible to contribute to performance against this issue. 4. Heat pumps can only be considered as a renewable technology when used in heating mode. Refer to Annex VI of Directive 2009/28/EC for more detail on accounting for energy from heat pumps. 5. Where MCS or CHPQA certification is not available, the design team must investigate the availability of alternative accreditation schemes in line with the Directives listed above, or an equivalent country or regional directive or standard. Where an accreditation scheme exists, it should be used for the purpose of verifying compliance of the specified LZC technology.
    [Show full text]
  • Demand-Response Management of a District Cooling Plant of a Mixed Use City Development
    Demand-Response Management of a District Cooling Plant of a Mixed Use City Development Segu Madar Mohamed Rifai Master of Science Thesis KTH - Royal Institute of Technology School of Industrial Engineering and Management Department of Energy Technology SE-100 44 STOCKHOLM Thesis Registration No.: EGI- 2012-011MSC Title: Demand-Response Management of a District Cooling Plant of a Mixed Use City Development. SEGU MADAR MOHAMED RIFAI Student Number: 731222 A-315 Approved Examiner Supervisor at KTH Date: 05/06/2012 Prof. Björn Palm Dr. Samer Sawalha Local Supervisor Dr. Hari Gunasingam Commissioner Contact person i | P a g e Abstract Demand for cooling has been increasing around the world for the last couple of decades due to various reasons, and it will continue to increase in the future particularly in developing countries. Traditionally, cooling demand is met by decentralised electrically driven appliances which affect energy, economy and environment as well. District Cooling Plant (DCP) is an innovative alternative means of providing comfort cooling. DCP is becoming an essential infrastructure in modern city development owning to many benefits compared to decentralized cooling technology. Demand Response Management (DRM) is largely applied for Demand Side management of electrical grid. Demand of electrical energy is closely connected with the demand of alternative form of energy such as heating, cooling and mechanical energy. Therefore, application of DR concept should be applied beyond the electrical grid; in particular, it could be applied to any interconnected district energy systems. District Cooling Plant is one of a potential candidate and Demand Response management solutions can be applied to DCP for sustainable operation.
    [Show full text]
  • Free Cooling – Outside Air Economizer White Paper #11
    FREE COOLING – OUTSIDE AIR ECONOMIZER WHITE PAPER #11 It’s like opening a window when it’s hot inside and cool outside. How much does it save? The easy answer is ‘it depends.’ To really find out, read further. You’ll see there are a lot of factors. Like all heat recovery concepts, a pre-requisite for success is to have the free heat (or free cooling) available at the same location and time as there is a need for it. The free heat in Atlanta has no practical use in Alaska because they are too far apart. Likewise, free cooling from outdoors doesn’t provide any value unless it is warm indoors at that time. Balance Temperature Buildings are like boxes. They have thermal losses and gains through the shell (envelope), and they also have appliances and activities inside that generate heat. See Figure 1. There will be a point where the envelope loss just matches the internal heat gains and neither heating nor cooling is required; above this ‘balance temperature’, cooling will be required. Source: Commercial Energy Auditing Reference Handbook, 3e Doty,S., Fairmont Press. Figure 1. Thermal Balance Temperature FREE COOLING – OUTSIDE AIR ECONOMIZER White Paper What is your building’s balance temperature? A building’s thermal balance temperature can be estimated with a method called regression, but there are also clues. See Table 1. If there is a lot of heat-producing equipment inside, the building becomes self- heating and will include hours in cooling mode when it is cold outside. Opportunity! If the heating and cooling load is mostly from envelope (not a lot of equipment), the balance point will be higher which means it probably won’t be hot inside while it is cold outside.
    [Show full text]
  • A Comprehensive Review of Thermal Energy Storage
    sustainability Review A Comprehensive Review of Thermal Energy Storage Ioan Sarbu * ID and Calin Sebarchievici Department of Building Services Engineering, Polytechnic University of Timisoara, Piata Victoriei, No. 2A, 300006 Timisoara, Romania; [email protected] * Correspondence: [email protected]; Tel.: +40-256-403-991; Fax: +40-256-403-987 Received: 7 December 2017; Accepted: 10 January 2018; Published: 14 January 2018 Abstract: Thermal energy storage (TES) is a technology that stocks thermal energy by heating or cooling a storage medium so that the stored energy can be used at a later time for heating and cooling applications and power generation. TES systems are used particularly in buildings and in industrial processes. This paper is focused on TES technologies that provide a way of valorizing solar heat and reducing the energy demand of buildings. The principles of several energy storage methods and calculation of storage capacities are described. Sensible heat storage technologies, including water tank, underground, and packed-bed storage methods, are briefly reviewed. Additionally, latent-heat storage systems associated with phase-change materials for use in solar heating/cooling of buildings, solar water heating, heat-pump systems, and concentrating solar power plants as well as thermo-chemical storage are discussed. Finally, cool thermal energy storage is also briefly reviewed and outstanding information on the performance and costs of TES systems are included. Keywords: storage system; phase-change materials; chemical storage; cold storage; performance 1. Introduction Recent projections predict that the primary energy consumption will rise by 48% in 2040 [1]. On the other hand, the depletion of fossil resources in addition to their negative impact on the environment has accelerated the shift toward sustainable energy sources.
    [Show full text]
  • Hvacwatersystems Waterside Free Cooling.Pdf
    HVAC Water Systems Waterside Free Cooling Summary Free cooling utilizes the evaporative cooling capacity of a cooling tower to indirectly produce chilled water for use in medium temperature loops, such as process cooling loops and sensible cooling loops. Free cooling is best suited for climates that have wetbulb temperatures lower than 55°F for 3,000 or more hours per year. It is most effectively applied to serve process and/or sensible cooling loops that between 50°F–70°F chilled water. Table 1. Free Cooling Application At least 3000 hours per Applicability year where wet bulb temperature is below: 55°F Process cooling water Process cooling, sensible 45°F cooling 35°F All chilled water use 1. Assumes process cooling water is between 60 to 70°F. 2. Assumes sensible cooling water is between 50 to 55°F. Principles • Chilled water systems use chillers that typically operate at 0.5 to 0.7 kW/ton in a partial load regime while free cooling systems typically operate at 0.05 to 0.15 kW/ton. 1 • A flat plate heat exchanger is used to isolate the chilled water loop from the open tower condenser water. With few exceptions, tower water is not reliably clean enough for use directly in the cooling loop. • The approach temperature on a cooling tower is critical for best results. A low approach temperature on the tower is critical to achieve the highest energy savings. • A traditional chiller is used to provide cooling during hot periods and as an always-available emergency backup. For a portion of the year, free cooling offers a non-compressor based backup to the traditional chiller.
    [Show full text]
  • Melink Intelli-Hood Snapshot of 4 Melink Customers a New Standard in Kitchen Ventilation Intelli-Hood Kitchen Ventilation Controls
    ®® Case Studies Melink Intelli-Hood Snapshot of 4 Melink customers A New Standard in Kitchen Ventilation Intelli-Hood Kitchen Ventilation Controls Savings & Benefits Other Intelli-Hood® Advantages Improves Energy Efficiency ® The Intelli-Hood controls improve energy efficiency 1. Eliminate drive losses and belt Supermarket Restaurant Hotel University by reducing the exhaust and make-up fan speeds during maintenance by specifying direct Annual energy savings Annual energy savings Annual energy savings idle periods. Typical annual operating savings are Annual energy savings drive fans. per location per location per location per location $1,500-$3,000 per hood, with a payback of 1-3 years. $2,340 $2,040 $5,500 $5,580 2. Reduce humidity problems associated Improves Kitchen Comfort ® with a negative building pressure. Current payback Current payback Current payback Current payback The Intelli-Hood controls improve kitchen comfort 1.8 years 2.2 years 2.1 years 2.3 years by reducing the supply of hot/humid make-up air during 3. Improve hood and building air idle periods. They also serve as an economizer when balance with variable-speed controls indoor and outdoor conditions are right for free cooling. Finally, the Intelli-Hood® controls reduce hood noise in the (verses belts and pulleys). kitchen up to 90% when the fans slow down. 4. Extend HVAC equipment life by Before-and-After Energy Savings Improves Fire Safety reducing run time and thus wear/tear The Intelli-Hood® controls can improve fire safety by of compressors, motors, heaters, etc. KW with the Intelli-Hood® monitoring the exhaust air temperature. If the temperature Actual reading from a current Intelli-Hood supermarket ® 5.
    [Show full text]
  • Echnica L Ssista Nce Tu Dy Umass Memorial Medical Center
    UMASS MEMORIAL MEDICAL CENTER POWER PLANT 55 LAKE AVENUE NORTH WORCESTER, MA T ECHNICAL ECHNICAL A SSISTANCE SSISTANCE PREPARED FOR S TUDY DCAMM Prepared by B2Q Associates, Inc. Andover, MA Revision Date 12/21/2015 TECHNICAL ASSISTANCE STUDY - WATERSIDE ECONOMIZER UMASS MEMORIAL MEDICAL CENTER - POWER PLANT Introduction .................................................................................................................................... 3 Contacts .......................................................................................................................................... 5 Approach & Modeling Methodology .............................................................................................. 6 Executive Summary Table ............................................................................................................... 7 Facility & Process Description ......................................................................................................... 8 Annual Chilled Water Load Profile ................................................................................................ 11 Energy Modeling Methodology .................................................................................................... 15 Baseline Chiller Plant Modeling ................................................................................................ 15 Power Plant Modeling............................................................................................................... 17 Energy Conservation
    [Show full text]
  • "Free" Cooling Using Water Economizers
    engineers newsletter volume 37–3 • providing insights for today’s hvac system designer "free" cooling using Standard 90.1 requirements Water Economizers The following sections of the Standard 90.1 prescriptive path are relevant for water economizers.[4] from the editor … Why economize? In past newsletters, we addressed the ability to accomplish "free" cooling by There are times of the year when a Section 6.5.1 Economizers. "Each artfully rearranging traditional cooling cooling system…" over the size equipment [1] and other ways to achieve system can use outdoor conditions to byproduct cooling virtually for free.[2] cool the building or process using the thresholds shown below "that has a fan We’ve also provided newsletters that standard cooling components to shall include either an air or water discussed air economizers and energy distribute its cooling effect. economizer." There are nine exceptions: code requirements.[3] small individual fan cooling units, In this EN, Susanna Hanson (Trane The most prevalent technique is an air spaces humidified above 35°F (2ºC) applications engineer) focuses on the economizer. When the temperature, or dew point for processes, systems with traditional methods of water-side enthalpy, of the outdoor air is low, condenser heat recovery, some economizing and associated energy code requirements. cooler outdoor air is used to reduce the residential applications, and systems temperature (or enthalpy) of air entering with minimal hours or cooling loads. the cooling coil. This can reduce or There is also an option to use higher eliminate mechanical cooling for much Let’s start with some definitions. efficiency equipment in lieu of an of the year in many climates.
    [Show full text]
  • Investigation of Separated Two-Phase Thermosiphon Loop for Relieving the Air-Conditioning Loading in Datacenter
    energies Article Investigation of Separated Two-Phase Thermosiphon Loop for Relieving the Air-Conditioning Loading in Datacenter Hafiz M. Daraghmeh 1 , Mohammed W. Sulaiman 1 , Kai-Shing Yang 2 and Chi-Chuan Wang 1,* 1 Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan; hafi[email protected] (H.M.D.); [email protected] (M.W.S.) 2 Green Energy & Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 300, Taiwan; [email protected] * Correspondence: [email protected]; Tel.: +886-3-5712121 Received: 28 November 2018; Accepted: 24 December 2018; Published: 29 December 2018 Abstract: This study investigates the feasibility of using R-134a filled separated two-phase thermosiphon loop (STPTL) as a free cooling technique in datacenters. Two data center racks one of them is attached with fin and tube thermosiphon were cooled by CRAC unit (computer room air conditioning unit) individually. Thermosiphon can help to partially eliminate the compressor loading of the CRAC; thus, energy saving potential of thermosiphon loop was investigated. The condenser is a water-cooled design and perfluoroalkoxy pipes were used as adiabatic riser/downcomer for easier installation and mobile capability. Tests were conducted with filling ratio ranging from 0 to 90%. The test results indicate that the energy saving increases with the rise of filling ratio and an optimum energy savings of 38.7% can be achieved at filling ratios of 70%, a further increase of filling ratio leads to a reduction in energy saving. At a low filling ratio like 10%, the evaporator starves for refrigerant and a very uneven air temperature distribution occurring at the exit of data rack.
    [Show full text]
  • A Solar Heating and Cooling System in a Nearly Zero-Energy Building: a Case Study in China
    Hindawi International Journal of Photoenergy Volume 2017, Article ID 2053146, 11 pages https://doi.org/10.1155/2017/2053146 Research Article A Solar Heating and Cooling System in a Nearly Zero-Energy Building: A Case Study in China 1,2 1 2 2 2 2 2 Zhifeng Sun, Yaohua Zhao, Wei Xu, Xinyu Zhang, Huai Li, Min Wang, Tao He, and 2 Dongxu Wang 1College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China 2Institute of Building Environment and Energy, China Academy of Building Research, Beijing 100013, China Correspondence should be addressed to Xinyu Zhang; [email protected] Received 5 January 2017; Revised 21 April 2017; Accepted 18 May 2017; Published 18 July 2017 Academic Editor: Michel Feidt Copyright © 2017 Zhifeng Sun et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The building sector accounts for more than 40% of the global energy consumption. This consumption may be lowered by reducing building energy requirements and using renewable energy in building energy supply systems. Therefore, a nearly zero-energy building, incorporating a solar heating and cooling system, was designed and built in Beijing, China. The system included a 35.17 kW cooling (10-RT) absorption chiller, an evacuated tube solar collector with an aperture area of 320.6 m2, two hot-water storage tanks (with capacities of 10 m3 and 30 m3, respectively), two cold-water storage tanks (both with a capacity of 10 m3), and a 281 kW cooling tower.
    [Show full text]
  • Performance Analysis and Control Strategies to Enhance Free Cooling
    ________________________________________________________________________________________________ Performance Analysis and Control Strategies to Enhance Free Cooling with an Active PCM-Heat Exchanger Navid Morovat1, José Agustín Candanedo2, Andreas K Athienitis1 1Concordia university, Montreal, Canada 2CanmetENERGY, Montreal, Canada free cooling Abstract peak load shifting This paper presents a simulation case study of an active active building systems thermal energy storage device with phase-change passive building systems materials (PCM) for free-cooling purposes. The charging/discharging of the PCM, arranged in layers in a In passive applications, PCMs are integrated into the heat exchanger, is done through a controlled air stream building envelopes to increase the effective thermal passing through these layers. First, the effect of airflow storage capacity in order to better energy saving and rate on charging/discharging time is investigated. Then, temperature regulation. The main problem with different control strategies targeting reduction in peak incorporating PCMs in the building envelope is the demand and HVAC system sizing are evaluated. Results difficulty of exchanging a high rate of heat between the show that for the present case-study 14% reduction in air and the PCM. Passive ways for cooling may also not energy consumption and 10% enhanced energy flexibility be as effective in extreme climate conditions. This is could be achieved using the PCM heat exchanger mainly because the outdoor ambient air temperature does (PCM-HX) for free cooling. not decrease sufficiently at night. Stetiu and Feustel (1998) found that for climates with relatively high Introduction ambient temperatures (above 17 °C) during the night, it The role of buildings as flexible loads is becoming more would be beneficial to force the supply air along the important; they can act as energy generators, energy storage surfaces to facilitate good heat exchange.
    [Show full text]