Parametric study for the long term energetic performance of geothermal energy piles

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2019-01-01
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en
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1st Nordic conference on Zero Emission and Plus Energy Buildings, 6-7 November 2019, Trondheim, Norway, IOP Conference Series: Earth and Environmental Science, Volume 352, issue 1
Abstract
Geothermal energy constitutes an important renewable resource that will become increasingly prominent in future constructions. A common method of extraction and usage consists of installing, inside the foundation piles of buildings, U-shaped heat exchangers called "energy piles". In this paper such installations are addressed by means of a full parametric study, performed for a hall-type commercial building in a cold climate. By computing the transient heat transfer between energy piles and ground for a period of 20 years, guidelines for a preliminary sizing of the geothermal system as a whole are provided. These are valid for this specific building and climate, for a clay-type soil and without assuming thermal storage. A highly nonlinear behaviour of the expected yield in relation to pile separation and evaporator extraction power is observed. Furthermore, 15m-long piles are found to be more efficient than those with double length, a smaller extraction power seems to be more favourable and differences in thepile diameter have little impact for heat transfer. A geothermal system sizing guide, which is useful for a preliminary quantitative test prior to any installation, is introduced. Even though our specific results are valid only for a commercial hall-type building in Finland, our procedure is qualitatively general and can be utilized for any given building type and climate zone.
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Ferrantelli , A , Fadejev , J & Kurnitski , J 2019 , Parametric study for the long term energetic performance of geothermal energy piles . in 1st Nordic conference on Zero Emission and Plus Energy Buildings, 6-7 November 2019, Trondheim, Norway . IOP Conference Series: Earth and Environmental Science , no. 1 , vol. 352 , Institute of Physics Publishing , Nordic Conference on Zero Emission and Plus Energy Buildings , Trondheim , Norway , 06/11/2019 . https://doi.org/10.1088/1755-1315/352/1/012011