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Main Authors: Zanchini, Enzo, Zanchini, Francesco, Naldi, Claudia
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2510.14421
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author Zanchini, Enzo
Zanchini, Francesco
Naldi, Claudia
author_facet Zanchini, Enzo
Zanchini, Francesco
Naldi, Claudia
contents An accurate design of a ground-coupled heat pump system requires the knowledge of the outlet fluid temperature from the borehole heat exchangers (BHEs), both in the short and long term. This paper fucuses on the short and medium term. In this time range, either 3D finite-element simulations or Thermal Resistance Capacity Models (TRCMs) can be applied. The former can yield very accurate results but require long computation times. The latter are much faster but cannot be fully precise, because they require simplifying assumptions. In this paper, we present a new method for the short-term and medium-term simulation of single U-tube BHEs, which combines the speed of TRCMs and the accuracy of finite-elements simulations. The method uses a TRCM to estimate the thermal response of the BHE, then corrects the results by interpolation with a dataset, which has been produced by running 54 finite-element simulations in various configurations. The model is implemented in a C++ program, available at the open-source online data repository of the University of Bologna. The program provides, within two seconds, the time evolution of the inlet, outlet and mean fluid temperature, of the mean BHE surface temperature, of the 3D and the effective borehole thermal resistance. It can be easily connected to long-term simulation tools to obtain the full-time-scale thermal response of a bore field.
format Preprint
id arxiv_https___arxiv_org_abs_2510_14421
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A combined thermal-resistance-capacity and finite-element model for very fast and accurate short- and medium-term simulations of single U-tube borehole heat exchangers
Zanchini, Enzo
Zanchini, Francesco
Naldi, Claudia
Applied Physics
An accurate design of a ground-coupled heat pump system requires the knowledge of the outlet fluid temperature from the borehole heat exchangers (BHEs), both in the short and long term. This paper fucuses on the short and medium term. In this time range, either 3D finite-element simulations or Thermal Resistance Capacity Models (TRCMs) can be applied. The former can yield very accurate results but require long computation times. The latter are much faster but cannot be fully precise, because they require simplifying assumptions. In this paper, we present a new method for the short-term and medium-term simulation of single U-tube BHEs, which combines the speed of TRCMs and the accuracy of finite-elements simulations. The method uses a TRCM to estimate the thermal response of the BHE, then corrects the results by interpolation with a dataset, which has been produced by running 54 finite-element simulations in various configurations. The model is implemented in a C++ program, available at the open-source online data repository of the University of Bologna. The program provides, within two seconds, the time evolution of the inlet, outlet and mean fluid temperature, of the mean BHE surface temperature, of the 3D and the effective borehole thermal resistance. It can be easily connected to long-term simulation tools to obtain the full-time-scale thermal response of a bore field.
title A combined thermal-resistance-capacity and finite-element model for very fast and accurate short- and medium-term simulations of single U-tube borehole heat exchangers
topic Applied Physics
url https://arxiv.org/abs/2510.14421