The Study Of GWHP Numerical Simulation On Plain Area Of Beijing City

Groundwater source heat pump (GWHP) air-conditioning technology, as a green, efficient, low costs and sustainable use of new technologies, has been widely used in the recent years. The dissertation set up the confined, unconfined groundwater flow and heat transport coupled models by FEFLOW5.4, a finite element simulation software, for GWHP appropriate areas in the plain area of Beijing. Study on the relationship of hydro-geological parameters, structural parameters of wells, pumping and injecting volume, injecting water temperature and natural groundwater flow with the aquifer geothermal distribution.Unconfined aquifer simulation results show that: consider the heat exchange between the atmosphere and aquifer could better characterize the vertical temperature distribution; consider the recharge of atmosphere, in the cooling period of GWHP, the temperature distribution has a rise trend according to water table; due to the high activity of natural groundwater flow in unconfined aquifer area, the shape of temperature distribution was elliptical, but the existence of natural groundwater flow can improve system efficiency. Confined aquifer simulation results show that: the distribution of temperature field in the aquifer system is mainly affected by pumping and injecting capacity and the temperature of injecting water, the shape of temperature field as a circle surrounding injecting well ; increased pumping and injecting capacity and reduce the distance between the pumping and injecting wells would result in pumping well's temperature variation increases; "little temperature difference, big flow" system has a bigger temperature field radius than "big temperature difference, small flow" system; when the pumping well and injecting well in different layers, the temperature of pumping well has less affected.Based on the simulation of unconfined and confined aquifer GWHP system in distance between pumping and injecting wells and the impact radius of temperature field, and compared with the experience formula of the impact radius, the reasonably distance between pumping and injecting wells of GWHP systems and impact radius of temperature field can be determinate. Further, the reserve of shallow geothermal resources in Beijing plaint area within the depth of 100m was 4.47×1010kw, under the condition of extracting 5℃energy and the system running for 120 days respectively in winter or summer.