Analytical Optimization of Vertical Closed-Loop Ground Source Heat Pump Systems

In this paper, we study the optimization of the operation of closed-loop ground source heat pump systems with any layout and any number n of vertical boreholes. Given the total required heat load, <i>q<sub>T</sub></i>, the goal is to maximize the rate of thermal gains from th...

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Main Authors: Konstantinos L. Katsifarakis, Yiannis N. Kontos
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Energies
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Online Access:https://www.mdpi.com/1996-1073/18/1/163
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author Konstantinos L. Katsifarakis
Yiannis N. Kontos
author_facet Konstantinos L. Katsifarakis
Yiannis N. Kontos
author_sort Konstantinos L. Katsifarakis
collection DOAJ
description In this paper, we study the optimization of the operation of closed-loop ground source heat pump systems with any layout and any number n of vertical boreholes. Given the total required heat load, <i>q<sub>T</sub></i>, the goal is to maximize the rate of thermal gains from the ground or, equivalently, to minimize the disturbance of the ground temperature at the location of the boreholes. This is achieved by optimizing the distribution of <i>q<sub>T</sub></i> to the individual boreholes. We prove analytically that, at any time, the weighted temperature disturbance is minimal when the following condition holds: the temperature change is the same at the locations of all boreholes. Our proof is based on the analogy between heat transfer due to conduction and water flow through aquifers, and we make use of the results obtained for pumping cost minimization from systems of wells under transient groundwater flow conditions in infinite confined aquifers. Finally, we present a procedure to calculate the optimal distribution of the total heat load to the individual boreholes at any given time. The procedure entails the solution of a linear system of n equations and n unknowns, which is explained by means of two theoretical application examples. Accuracy of the results is also discussed.
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spelling doaj-art-7e21583b745744c3bb4c7f0cbf3b007f2025-01-10T13:17:17ZengMDPI AGEnergies1996-10732025-01-0118116310.3390/en18010163Analytical Optimization of Vertical Closed-Loop Ground Source Heat Pump SystemsKonstantinos L. Katsifarakis0Yiannis N. Kontos1Division of Hydraulics and Environmental Engineering, Department of Civil Engineering, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, GreeceDivision of Hydraulics and Environmental Engineering, Department of Civil Engineering, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, GreeceIn this paper, we study the optimization of the operation of closed-loop ground source heat pump systems with any layout and any number n of vertical boreholes. Given the total required heat load, <i>q<sub>T</sub></i>, the goal is to maximize the rate of thermal gains from the ground or, equivalently, to minimize the disturbance of the ground temperature at the location of the boreholes. This is achieved by optimizing the distribution of <i>q<sub>T</sub></i> to the individual boreholes. We prove analytically that, at any time, the weighted temperature disturbance is minimal when the following condition holds: the temperature change is the same at the locations of all boreholes. Our proof is based on the analogy between heat transfer due to conduction and water flow through aquifers, and we make use of the results obtained for pumping cost minimization from systems of wells under transient groundwater flow conditions in infinite confined aquifers. Finally, we present a procedure to calculate the optimal distribution of the total heat load to the individual boreholes at any given time. The procedure entails the solution of a linear system of n equations and n unknowns, which is explained by means of two theoretical application examples. Accuracy of the results is also discussed.https://www.mdpi.com/1996-1073/18/1/163geothermalground source heat pump (GSHP)district heatingground temperature changeoptimizationanalytical solution
spellingShingle Konstantinos L. Katsifarakis
Yiannis N. Kontos
Analytical Optimization of Vertical Closed-Loop Ground Source Heat Pump Systems
Energies
geothermal
ground source heat pump (GSHP)
district heating
ground temperature change
optimization
analytical solution
title Analytical Optimization of Vertical Closed-Loop Ground Source Heat Pump Systems
title_full Analytical Optimization of Vertical Closed-Loop Ground Source Heat Pump Systems
title_fullStr Analytical Optimization of Vertical Closed-Loop Ground Source Heat Pump Systems
title_full_unstemmed Analytical Optimization of Vertical Closed-Loop Ground Source Heat Pump Systems
title_short Analytical Optimization of Vertical Closed-Loop Ground Source Heat Pump Systems
title_sort analytical optimization of vertical closed loop ground source heat pump systems
topic geothermal
ground source heat pump (GSHP)
district heating
ground temperature change
optimization
analytical solution
url https://www.mdpi.com/1996-1073/18/1/163
work_keys_str_mv AT konstantinoslkatsifarakis analyticaloptimizationofverticalclosedloopgroundsourceheatpumpsystems
AT yiannisnkontos analyticaloptimizationofverticalclosedloopgroundsourceheatpumpsystems