Abstract
In this work, numerical simulation calculations were performed to investigate the minimum ground temperature that occurs when extracting thermal energy in a horizontal ground heat exchanger system in the Central European climate. The influence of ground thermal conductivity, heat flux extracted from the ground, periodic interruptions in the operation of the heat exchanger, periodic supply of heat energy to the ground, relative humidity of the ambient air, evaporation rate coefficient, and convective heat transfer coefficient on the ground minimum temperature were investigated. Based on the simulation, it was found that the high value of ground thermal conductivity favorably affects the operation of the installation with a ground heat exchanger. Both the reduction of the maximum heat flux taken from the ground, as well as periodic interruptions in the operation of the exchanger effectively protects the ground against excessive cooling. Further, it was found that heat supply to the ground in summer only slightly raises its minimum temperature, as well as the decrease of the relative humidity of the ambient air and evaporation rate coefficient. The change of the convective heat transfer coefficient has no significant impact on the minimum annual ground temperature.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
This work aims to carry out calculations to determine the minimum temperatures that can occur in the ground, where a ground heat exchanger coupled with a heat pump and with an installation for space heating is installed
The carried out simulations show that the ground thermal conductivity significantly affects the value of the minimum temperature occurring at the depth of the heat exchanger’s installation
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Despite the existence of natural thermal regeneration in the summer season, too intensive exploitation of a heat exchanger during the heating season can cause excessive cooling of the ground This phenomenon is disadvantageous from the point of view of heat extraction when using a ground exchanger, because of the effect of increasing the temperature difference between the heat sources and due to the possibility of deterioration of the contact of the ground with the exchanger pipes caused by freezing of the ground near the GHE. This work aims to carry out calculations to determine the minimum temperatures that can occur in the ground, where a ground heat exchanger coupled with a heat pump and with an installation for space heating is installed It was investigated which parameters most strongly affect the value of the minimum ground temperature. The calculations use the ground heat transfer model described in [19]
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