Experimental research on the characteristics of single-well groundwater heat pump systems

Abstract

Research on single-well groundwater heat pump (SWGWHP) systems is insufficient. To bridge this gap, this study sets up a physical simulation experiment table to examine the flow and heat transfer law in these systems. It experimentally investigates the distance between pumping and injection screens (DPI), initial aquifer temperature, flow rate of the outlet water, and load capacity variations. The results indicate that the outlet water temperature of the SWGWHP considerably improves when the DPI is increased. Increasing the DPI is an appropriate measure when practical conditions permit and is more effective when thermal breakthrough is severe in the thermal well. Additionally, the heat absorption percentage is greater than the heat rejection percentage when the initial aquifer temperature changes to the same extent as it does in three single-well systems. Therefore, the variation in the initial aquifer temperature should be considered in heating-dominated buildings. Moreover, the amount of heat transfer and heat-affected zone of thermal wells considerably improve on increasing the flow rate of the outlet water under good permeability conditions. The heat-affected zone of a standing column well (SCW) is the smallest, followed by that of the pumping and recharging well (PRW) and forced external circulation standing column well (FECSCW). Furthermore, the load capacity of the SCW is the least among the three systems. However, increasing the flow rate of the outlet water can improve the load capacity of the SCW.