Investigation of Theoretical Models, Pumping-Recharge Well Arrangements and System Performance of Abandoned Mine Water Source Heat Pump

Abandoned mines are rich in geothermal resources. In this article, the feasibility of applying a water resource heating system in abandoned mines is explored, adopting mine water in the extraction zone as the research object. First, the utilization mode of geothermal resources in abandoned mines is introduced, and the applicable scenarios of different mine water heating methods are clarified. Second, to prevent the heat transfixion phenomenon caused by an irrational arrangement of pumping wells, a three-dimensional numerical calculation model for multiphysical field coupling of the pumping wells of a water source heat pump in abandoned mines is established, and 14 distinct types of well arrangements are simulated. According to the occurrence degree of heat transfixion, the most reasonable arrangement of pumping wells is selected. The influences of different recharge temperatures, pumping and recharging flow rates, well spacings, hydraulic gradients, aquifer thicknesses, porosities and other factors on the pumping temperature are studied according to the selected pumping and recharging well arrangement scheme. Finally, by choosing a residential building as the analysis object, a simulation model of the abandoned mine water source heat pump heating system is constructed, which is compared with a gas boiler heating system, revealing the energy savings and environmental protection benefits of the abandoned mine water source heat pump system. The results of this paper provide a scientific basis for the utilization of mine water geothermal resources, which can facilitate the transformation of abandoned mines and provide theoretical and technical guidance in engineering practice.