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A comparative study on borehole heat exchanger size for direct ground coupled cooling systems using active chilled beams and TABS

Arghand, Taha ; Javed, Saqib LU ; Trüschel, Anders and Dalenbäck, Jan Olof (2021) In Energy and Buildings 240.
Abstract

Direct ground cooling is a method for cooling buildings whereby free cooling is provided by circulating water through borehole heat exchangers (BHEs). Since no refrigeration cooling is involved, supply water temperature to the building's cooling system is dependent mainly on BHE sizing. This study investigates the sizing of BHEs for direct ground cooling systems, with a particular focus on the influence of terminal unit types and their operating strategies. Experimental results using a direct ground-coupled active chilled beam (ACB) system are used to develop a simulation model for an office building. The model is also modified for thermally activated building systems (TABS). The simulation results show that using TABS instead of ACBs... (More)

Direct ground cooling is a method for cooling buildings whereby free cooling is provided by circulating water through borehole heat exchangers (BHEs). Since no refrigeration cooling is involved, supply water temperature to the building's cooling system is dependent mainly on BHE sizing. This study investigates the sizing of BHEs for direct ground cooling systems, with a particular focus on the influence of terminal unit types and their operating strategies. Experimental results using a direct ground-coupled active chilled beam (ACB) system are used to develop a simulation model for an office building. The model is also modified for thermally activated building systems (TABS). The simulation results show that using TABS instead of ACBs for a similar BHE reduced the ground peak hourly loads, resulting in a lower borehole outlet temperature. Resizing BHE depth to reach similar maximum borehole outlet temperatures according to the actual heat extraction rate from the cooling systems resulted in a significantly shorter BHE depth with TABS compared to ACBs. However, indoor temperature was generally warmer with TABS, due to their slower heat extraction rate from the room. The findings are practical for analysing the design and operation of BHEs for different types of terminal units.

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publishing date
type
Contribution to journal
publication status
published
subject
keywords
Active chilled beam, Borehole heat exchanger, Direct ground cooling, Free cooling, Geocooling, GeoTABS
in
Energy and Buildings
volume
240
article number
110874
pages
12 pages
publisher
Elsevier
external identifiers
  • scopus:85102972368
ISSN
0378-7788
DOI
10.1016/j.enbuild.2021.110874
language
English
LU publication?
no
additional info
Funding Information: This work was financially supported by the Swedish Energy Agency (Energimyndigheten) through its E2B2 national research programme. The in-kind contribution of laboratory facilities by Swegon and Lindab is gratefully appreciated. We are particularly grateful to Håkan Larsson for his lab assistance. Valuable discussions with Carl-Ola Danielsson (Swegon) and Göran Hultmark (Lindab) are also acknowledged. Publisher Copyright: © 2021 The Author(s) Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
id
f579a533-30a6-4d9d-874e-4c61e39e1b07
date added to LUP
2021-03-31 18:49:16
date last changed
2021-04-15 09:03:28
@article{f579a533-30a6-4d9d-874e-4c61e39e1b07,
  abstract     = {<p>Direct ground cooling is a method for cooling buildings whereby free cooling is provided by circulating water through borehole heat exchangers (BHEs). Since no refrigeration cooling is involved, supply water temperature to the building's cooling system is dependent mainly on BHE sizing. This study investigates the sizing of BHEs for direct ground cooling systems, with a particular focus on the influence of terminal unit types and their operating strategies. Experimental results using a direct ground-coupled active chilled beam (ACB) system are used to develop a simulation model for an office building. The model is also modified for thermally activated building systems (TABS). The simulation results show that using TABS instead of ACBs for a similar BHE reduced the ground peak hourly loads, resulting in a lower borehole outlet temperature. Resizing BHE depth to reach similar maximum borehole outlet temperatures according to the actual heat extraction rate from the cooling systems resulted in a significantly shorter BHE depth with TABS compared to ACBs. However, indoor temperature was generally warmer with TABS, due to their slower heat extraction rate from the room. The findings are practical for analysing the design and operation of BHEs for different types of terminal units.</p>},
  author       = {Arghand, Taha and Javed, Saqib and Trüschel, Anders and Dalenbäck, Jan Olof},
  issn         = {0378-7788},
  language     = {eng},
  month        = {06},
  publisher    = {Elsevier},
  series       = {Energy and Buildings},
  title        = {A comparative study on borehole heat exchanger size for direct ground coupled cooling systems using active chilled beams and TABS},
  url          = {http://dx.doi.org/10.1016/j.enbuild.2021.110874},
  doi          = {10.1016/j.enbuild.2021.110874},
  volume       = {240},
  year         = {2021},
}