Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes

Groundwater-filled boreholes are a common solution in Scandinavian installations of ground source heat pumps (GSHP) due to the particular hydro-geological conditions with existing bedrock, and groundwater levels close to the surface. Different studies have highlighted the advantage of water-filled b...

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Autores principales:	Oleg Todorov, Kari Alanne, Markku Virtanen, Risto Kosonen
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	ground-source heat pump (GSHP) ground-coupled heat exchangers (GHE) groundwater-filled boreholes optimization borehole effective thermal resistance distributed temperature sensing (DTS) Technology T
Acceso en línea:	https://doaj.org/article/5da9a814a28d4b91914a3ae131b9bba1
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id	oai:doaj.org-article:5da9a814a28d4b91914a3ae131b9bba1
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spelling	oai:doaj.org-article:5da9a814a28d4b91914a3ae131b9bba12021-11-11T15:44:44ZDifferent Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes10.3390/en142169081996-1073https://doaj.org/article/5da9a814a28d4b91914a3ae131b9bba12021-10-01T00:00:00Zhttps://www.mdpi.com/1996-1073/14/21/6908https://doaj.org/toc/1996-1073Groundwater-filled boreholes are a common solution in Scandinavian installations of ground source heat pumps (GSHP) due to the particular hydro-geological conditions with existing bedrock, and groundwater levels close to the surface. Different studies have highlighted the advantage of water-filled boreholes compared with their grouted counterparts since the natural convection of water within the borehole tends to decrease the effective thermal resistance <i>R<sub>b</sub></i>. In this study, several methods are proposed for the evaluation and modeling of the effective thermal resistance of groundwater-filled boreholes. They are based on distributed temperature sensing (DTS) measurements of six representative boreholes within the irregular 74-single-U 300 m-deep borehole field of Aalto New Campus Complex (ANCC). These methods are compared with the recently developed correlations for groundwater-filled boreholes, which are implemented within the python-based simulation toolbox <i>Pygfunction</i>. The results from the enhanced <i>Pygfunction</i> simulation with daily update of <i>R<sub>b</sub></i> show very good agreement with the measured mean fluid temperature of the first 39 months of system operation (March 2018–May 2021). It is observed that in real operation the effective thermal resistance <i>R<sub>b</sub></i>* can vary significantly, and therefore it is concluded that the update of <i>R<sub>b</sub></i>* is crucial for a reliable long-term simulation of groundwater-filled boreholes.Oleg TodorovKari AlanneMarkku VirtanenRisto KosonenMDPI AGarticleground-source heat pump (GSHP)ground-coupled heat exchangers (GHE)groundwater-filled boreholesoptimizationborehole effective thermal resistancedistributed temperature sensing (DTS)TechnologyTENEnergies, Vol 14, Iss 6908, p 6908 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	ground-source heat pump (GSHP) ground-coupled heat exchangers (GHE) groundwater-filled boreholes optimization borehole effective thermal resistance distributed temperature sensing (DTS) Technology T
spellingShingle	ground-source heat pump (GSHP) ground-coupled heat exchangers (GHE) groundwater-filled boreholes optimization borehole effective thermal resistance distributed temperature sensing (DTS) Technology T Oleg Todorov Kari Alanne Markku Virtanen Risto Kosonen Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes
description	Groundwater-filled boreholes are a common solution in Scandinavian installations of ground source heat pumps (GSHP) due to the particular hydro-geological conditions with existing bedrock, and groundwater levels close to the surface. Different studies have highlighted the advantage of water-filled boreholes compared with their grouted counterparts since the natural convection of water within the borehole tends to decrease the effective thermal resistance <i>R<sub>b</sub></i>. In this study, several methods are proposed for the evaluation and modeling of the effective thermal resistance of groundwater-filled boreholes. They are based on distributed temperature sensing (DTS) measurements of six representative boreholes within the irregular 74-single-U 300 m-deep borehole field of Aalto New Campus Complex (ANCC). These methods are compared with the recently developed correlations for groundwater-filled boreholes, which are implemented within the python-based simulation toolbox <i>Pygfunction</i>. The results from the enhanced <i>Pygfunction</i> simulation with daily update of <i>R<sub>b</sub></i> show very good agreement with the measured mean fluid temperature of the first 39 months of system operation (March 2018–May 2021). It is observed that in real operation the effective thermal resistance <i>R<sub>b</sub></i>* can vary significantly, and therefore it is concluded that the update of <i>R<sub>b</sub></i>* is crucial for a reliable long-term simulation of groundwater-filled boreholes.
format	article
author	Oleg Todorov Kari Alanne Markku Virtanen Risto Kosonen
author_facet	Oleg Todorov Kari Alanne Markku Virtanen Risto Kosonen
author_sort	Oleg Todorov
title	Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes
title_short	Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes
title_full	Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes
title_fullStr	Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes
title_full_unstemmed	Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes
title_sort	different approaches for evaluation and modeling of the effective thermal resistance of groundwater-filled boreholes
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/5da9a814a28d4b91914a3ae131b9bba1
work_keys_str_mv	AT olegtodorov differentapproachesforevaluationandmodelingoftheeffectivethermalresistanceofgroundwaterfilledboreholes AT karialanne differentapproachesforevaluationandmodelingoftheeffectivethermalresistanceofgroundwaterfilledboreholes AT markkuvirtanen differentapproachesforevaluationandmodelingoftheeffectivethermalresistanceofgroundwaterfilledboreholes AT ristokosonen differentapproachesforevaluationandmodelingoftheeffectivethermalresistanceofgroundwaterfilledboreholes
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Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes

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