The Impact of the Heat Pump Horizontal Ground Heat Exchanger Operation on the Soil Thermal State

When designing heat pump heating systems using ground heat, one of the current tasks is the selection of rational thermodynamic operating modes of the heat pump. The aim of the article is to create a convenient tool for selecting the operating and design parameters of horizontal ground heat exchangers (GHE) of ground source heat pumps, taking into account the impact of their operation on the thermal potential of the soil. The temperature field of the soil mass undisturbed by the influence of the ground heat exchanger was studied. Based on solving the coupled problem of heat conduction in the soil and heat exchange in the GHE in a non-stationary formulation using the experimental design method, a regression equation of the heat flow from the soil to the linear meter of the GHE with a coolant on the main operating and design parameters of the GHE was obtained. Using the obtained regression equation, the impact of GHE operation on the depletion of the soil's thermal potential, as well as the effect of thermal interference between parallel sections of the GHE pipe, was studied. As a result of numerical studies, the most rational option of GHE with 9 parallel pipes with a spacing of 1 m between them was selected. The obtained results will allow the soil to be used as an energy source for a long time without leading to its thermal depletion while providing the required level of heat production in the heat pump.