A preliminary experimental investigation on groundwater temperature field influenced by groundwater source heat pump (GWHPS) in red beds area

Groundwater heat pump systems (GWHPS) is a kind of shallow geothermal energy utilization approach with the lowest cost, and it develops very fast in recent years. Previous study mainly focused on the pore water in the Quaternary unconsolidated formation, however, the research on groundwater in red beds area is still blank. In this paper, taking the bedrock fissure water of red beds in Chongqing as the research object, a series of pair experiments were conducted successfully. During the experiments, some devices for measuring water temperature, water level and flow rate are placed in observation and testing wells. Water level, flow rate data and the duration curves of water temperature at different depths of every wells were obtained. According to the above data, the initial distribution and spatial and temporal variation characteristics of groundwater temperature field were analyzed. Results showed that the variation of underground water temperature field in the site was mainly affected by the natural ground temperature field and initial temperature, the location of injection well, the depth of water injection nozzle and the injection water temperature, etc. It is speculated that the boundary of the temperature influence range caused by water injection are as follows: on the plane, the boundary shape is asymmetric near ellipse with injection well as the center of the circle, while in space, the injection well becomes the approximate ellipsoidal core of the temperature field boundary. The research results can provide some references for the further development and application of ground water source heat pump in the red bed area.