Assessment of the Impact of the Local Geological Structure on the Efficiency of Ground-Source Heat Pump

Ground-source heat pumps are widely applied technology for building heating, cooling and DHW production, which gained considerable development over last years. However, the technology faces number of challenges consequent on the ever-increasing efficiency demand in parallel with environment-friendly usage of low-temperature energy sources, inter alia ground, which is freely available all over the year. The most commonly way of extracting heat accumulated in near-surface layers of the ground is to use vertical heat exchanger, also called borehole heat exchanger, with intermediary agent. The aim of the study was to assess the influence of local geological structure on the efficiency of the ground-source heat pump. Assessment was conducted based on the elementary computational assumptions, the borehole data obtained from the Polish Geological Institute-National Research Institute and the defined thermal coefficients, and consequently the heat transfer rate values in selected measurement points were determined. As a result, the efficiency of selected boreholes were determined in relation to the previously established power demand for selected building. In the most parts of area studied, in selected measurement points, sands, clay gravels and clays dominated with vary thickness of particular types of land. Moreover, more favorable parameters for geothermal installations were specified in locations where the heat transfer coefficient of particular layers were lower, but the average heat transfer coefficient for borehole was higher.