The effectiveness of night ventilation for the thermal

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Applied Thermal Engineering 146 2019 190 202,Contents lists available at ScienceDirect. Applied Thermal Engineering, journal homepage www elsevier com locate apthermeng. Research Paper, The e ectiveness of night ventilation for the thermal balance of an aquifer T. thermal energy storage,Basar Bozkaya Wim Zeiler, Department of Built Environment Eindhoven University of Technology De Zaale PO Box 513 5600 MB Eindhoven the Netherlands. H I GH L IG H T S, The ATES system achieved a thermal balance of 11 12 using regeneration strategies.
Co simulation method was applied using MATLAB TRNSYS and COMSOL. Night ventilation was determined as a prominent option for thermal balancing methods. The system COP was improved by 26 4 by using night ventilation. A R T I C LE I N FO A B S T R A C T, Keywords Aquifer thermal energy storage ATES is a signi cant source of heating cooling systems due to its energy and. Aquifer thermal energy storage cost e cient operation To ensure environmental and energy sustainability the use of ATES is governed by strict. Aquifer thermal regulations one of which is the requirement of maintaining a balance in the amount of heat transfer into the. Thermal imbalance aquifer ground In general the combination of a heat pump HP and an air handling unit AHU are commonly used to. Regeneration aquifer thermal, achieve this thermal balance through regeneration strategies for cooling dominated loads However this ap. proach increases the operational cost and energy consumption of ATES heating cooling systems In this paper. an alternative approach that makes use of night ventilation NV for regeneration is evaluated In addition the. operational cost and energy e ciencies of the commonly used combination of an HP and AHU are compared to. those associated with NV operation The results show that using NV for the regeneration of the cold well could. reduce energy consumption by 19 3 MWh year which amounts to a 26 4 increase in system coe cient of. performance COP, 1 Introduction cooling heating system have been already proven 4 Due to the highly. e cient energy storage capabilities of ATES these systems are a good. To reduce the energy consumption of heating and cooling systems in option for achieving the goals of carbon emission reduction and im. the built environment the ground has been identi ed as an e cient proving the energy e ciency of the built environment. energy storage source in areas where ground conditions are suitable for Similar to many other technical solutions the use of ATES is con. the availability of the underground water 1 2 Thermal systems such trolled by governmental regulations 1 Speci cally in locations. as an aquifer thermal energy system ATES that make use of ground where ATES systems are densely installed regulations are strict with. water for long term storage of thermal energy are now in coastal areas regard to installation of new systems and the preservation of their long. becoming common features of modern large buildings due to the cost term e ciency One of these regulations is the maintenance of thermal. e ectiveness of the system due to suitable ground and weather condi balance in the amount of the heat injected into and extracted from the. tions When used in a building an ATES system removes heat from the ground Achieving thermal balance in the ground prevents future. building during cooling periods and provides heat during periods of thermal interaction between the well groups The imbalance between. heating The cold and heat extracted from the building are stored in heating or cooling building loads in a particular system results in. separate warm and cold wells underground with temperatures between dominance of either the warm or cold well which degrades the other. 16 and 18 C in the warm well and between 6 and 8 C in the cold well well over the long term as a result of thermal interaction 5 According. 1 3 The economic and technical advantages of ATES over traditional to the regulative framework for the Netherlands an ATES system. Corresponding author,E mail address b bozkaya tue nl B Bozkaya. https doi org 10 1016 j applthermaleng 2018 09 106. Received 24 April 2018 Received in revised form 4 August 2018 Accepted 24 September 2018. Available online 26 September 2018, 1359 4311 2018 The Authors Published by Elsevier Ltd This is an open access article under the CC BY license.
http creativecommons org licenses BY 4 0, B Bozkaya W Zeiler Applied Thermal Engineering 146 2019 190 202. Fig 1 An ATES system in cooling and regeneration mode modi ed from 9. should be in a thermal balance range of 0 15 over a period of system level where ATES is connected to HVAC system 10 19 Those. 5 10 years 6 studies 10 19 were based on some parametric studies for operational. For a cooling dominated building load in order to maintain the settings without taking into account the in uence of the dynamic. thermal balance of a well within the required range heat pumps HPs building load However in the real applications the thermally un. 4 7 8 cooling towers CTs 9 10 and air handling units AHUs 4 7 balanced building load is inevitable and has signi cant in uence on the. are used to compensate for the surplus heat in the ground Thermal performance which was proven in experimental analysis 8 4 Al. balancing methods are also known as regeneration methods Fig 1 though the use of AHUs and HPs for cold compensation is very common. illustrates the system studied in 9 In order to balance the surplus heat in practice 3 4 8 20 for ATES system the use of NV as a viable al. injection to the warm well an AHU is activated when the ambient air ternative has been limited Therefore this study aims to evaluate the. temperature falls below 4 C to expel the heat from the warm well to be performance of these two thermal balancing strategies The perfor. injected in the cold well as cold source It is common practice to use the mance of the strategies is evaluated based on two metrics the e cient. heating cooling coil of an AHU and HP together as cold compensators operation of ATES and the operational costs for thermal balancing In. 8 7 In an experimental study of a functional ATES system by this study the operation cost and energy e ectiveness of the two. Vandhout et al 4 it was demonstrated that the AHU was used for cold thermal balancing strategies are analyzed One of these thermal bal. compensation The AHU was activated for thermal balancing when the ancing strategies is utilizing AHU in DC mode and utilizing HP in HPC. ambient air temperature was lower than 4 C during non o ce hours to mode as was applied in 4 In the other strategy HPC is replaced with. expel additional heat from the ground This approach is called direct NV using AHU thus air handling unit is utilized in DC and NV mode It. compensation DC from an AHU 4 In cases where cold compensation is the aim of this study to determine the e ectiveness of NV as the cold. is not su ciently achieved by the AHU the HP is activated to com compensation method The cost of the compensation methods is ana. pensate for the remaining thermal imbalance ratio This approach is lyzed numerically A cooling dominated building is considered as a case. called direct compensation from heat pump HPC Unlike an AHU the study based on the fact that buildings are becoming more cooling. operation of HPs is not limited to the ambient air temperature which dominated due to improved air tightness and advanced insulation. makes an HP a reliable cold heat compensation unit techniques 1 9. Another approach that can be used for cold compensation is night The remaining sections of the paper are structured as follows First. ventilation NV Night ventilation is used in buildings to increase the the base case with cooling dominancy is presented followed by two. e ciency of cooling and decrease the cooling load in the building compensation control strategies applied to this case Correspondingly. 11 13 Night ventilation is capable of removing a portion of accu the heat transfer characteristics and the in uence on the temperature of. mulated heat from a building by utilizing the lower outside tempera the ATES system are presented Finally the energy performance and. tures present at night Thus the quantity of heat injection into the operational costs are calculated. ground decreases due to the decreased cooling and peak cooling de. mand on the ATES system which assists the system in eliminating HP 2 Previous studies. operation in the cooling mode from the ATES system while at the same. time reaching a thermal balance between the heating and cooling de Since ATES systems are commonly applied in commercial buildings. mand the majority of these systems are exposed to cooling dominant building. So far the studies concerning ATES are limited to the advanced loads 10 Aquifer thermal energy storage is an energy e cient system. thermal modelling of underground 14 18 and few simulation on the 3 10 However thermal imbalances should be accounted for in. B Bozkaya W Zeiler Applied Thermal Engineering 146 2019 190 202. Some hybrid ATES applications worldwide, Ref Location Cooling dominated Heating dominated Cold warm well injection System components Building type. 31 Eindhoven Netherlands 6 16 ATES HP CT University. 7 Utrecht Netherlands 8 14 ATES HP AHU O ce building. 10 Tehran Iran 3 14 43 65 ATES HP CT solar thermal Residential building. 32 Bucharest Romania 5 15 35 50 ATES HP CHP Community building. 9 Hamburg Munich Berlin 8 14 ATES CT HP Data center. 13 Rostock Germany 10 50 ATES HP solar thermal boiler Collective system. 33 Oslo Norway ATES HP boiler Airport,34 Mersin Turkey 18 ATES AHU Commercial building. 4 Antwerp Belgium 8 18 ATES HP Hospital,35 Adana Turkey 9 20 ATES AHU Hospital. 6 Berlin Germany 5 22 ATES AHU Commercial building. 27 Shanghai China 40 ATES Exhibition Hall,26 Shanghai China 11 17 25 30 ATES.
29 Ottowa Canada ATES University,23 Alabama USA 35 81 ATES Commercial building. overall system performance due to the extra cost of cold regeneration settings It was observed that none of those studies 10 8 32 included. As thermal imbalance grows the system will incur additional costs for the thermal imbalance in uence on the system performance However. the compensation of this thermal imbalance 1 practically thermal imbalances on the building load should be taken. ATES systems have been popularly used in Canada 21 22 USA into account since the building load pro le has direct in uence on the. 23 25 Asia 26 28 and Europe 26 30 Due to the lack of simu temperature pro le In addition the operational cost from the thermal. lation tools for ATES most previous studies have been based on ex compensation methods needs to be evaluated as well since they are. perimental studies with a focus on groundwater quality 26 feasibility caused by the extra energy consumption within the system. studies 29 and performance analysis 1 4 7 13 23 27 Table 1 shows In practical applications 4 thermal balance of ATES has been. a list of experimental studies in which thermal imbalances are ad achieved only through increasing the amount of charged cold in the. dressed The Technical University of Eindhoven utilizes the largest size ground by utilizing DC and HPC methods The alternative solution. ATES system on its campus and this produces more than 20 MWh of presented in this paper achieves thermal balance by increasing the. energy in the Netherlands 31 Due to the internal heat gain in the amount of charged cold using DC while simultaneously decreasing the. buildings and high cooling demand of laboratories the university has a cooling demand using NV which results in less heat injection to the. cooling dominated load pro le Therefore cooling supply from the ground in the building Therefore this paper intended to explore the. ATES system is supported by a cooling tower CT which balances the performance of NV as cold compensation strategy in substitute for HP. amount of heat underground by acting as supplementary heat rejecter. 37 Similarly Stockton College in New Jersey utilizes ATES connected 3 Methodology. to a CT for additional heat rejection 10 A commercial building lo. cated in Utrecht employs AHU to charge the cold well when the am 3 1 Case study building and system description. bient temperature is suitable and an HP when AHU are not utilized. 10 Related to this Vanhoudt et al 4 and Kranz et al 6 analyzed The building model in the case study is an o ce building in the. how the ATES system uses AHUs to regenerate cold wells Netherlands The building has a total area of 3520 m2 and volume of. Vanhoudt et al 4 conducted an experimental study of an ATES 9370 m3 It is a modern building with a cooling dominant building load. system for a Belgian hospital and concluded that the system utilizes due to advanced insulation techniques and a high amount of internal. AHU and an HP depending on the thermal imbalance ratio The HP heat gain The building requires an annual heat injection of 426 MWh. operates at peak hours when ATES is not su cient for direct cooling In and heat extraction of 86 MWh The ATES system works in a cyclical. order to eliminate HP operation either ATES temperatures can be mode The injection temperature was designed at 16 C for the warm. lowered through additional cold storage or the cooling demand can be well and 8 C for the cold well The maximum heating or cooling ca. decreased One o ce building in the Netherlands is utilizing NV to pacity varies throughout the year depending on the extraction tem. Aquifer thermal energy storage Aquifer thermal Thermal imbalance aquifer Regeneration aquifer thermal ABSTRACT Aquifer thermal energy storage ATES is a signi cant source of heating cooling systems due to its energy and cost e cient operation To ensure environmental and energy sustainability the use of ATES is governed by strict

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