THERMAL MODELING OF GROUNDWATER HEAT PUMP WITH PUMPING RECHARGE IN THE SAME WELL

摘要

Groundwater Heat Pump with Pumping & Recharging in the Same Well (GWHPPRSW) which is a new-style groundwater heat pump system had emerged in recent years in China. In this system, pumping and recharging occur simultaneously at the same plane spot but different depth of aquifer. The Pumping & Recharging Well (PRW) is divided into three parts by clapboards: low pressure (production) space, seals section and high pressure (injection) space. PRW is helpful to injection of a certain extent, reduces the area of plot and also could cause the thermal breakthrough. Thus, it is very important for the analysis of thermal characteristic. In this paper, heat transfer of groundwater caused by GWHPPRSW is analyzed firstly. The model of groundwater heat transfer in unitary homogenous confined aquifer in winter with constant groundwater flow has been established. Numerical simulation in typical fine sand confined aquifer is presented based on the model. The change of average pumping temperature and aquifer temperature in winter are analyzed in detail. The average pumping temperature reduces 3.6 °C within a whole winter. It is feasible to the region where the initial temperature of groundwater is higher than 13 °C. The thermal effective radius (TER) of GWHPPRSW is far to 74m, farther than that of Ground-Coupled Heat Pump (GCHP), because of convection and thermal dispersion. The system can make one PRW burden more load.