Investigation Of Heat Seepage Transfer Of Aquifer With Pumping And Recharge In Ground Water Heat Pump System

The design of a high efficiency,energy saving and environmental friendly groundwater source heat pump system is closely related to the study of heat infiltration and heat transfer of underground soil.At present,the temperature field simulation of pumping and filling well area is still in its infancy in China.There are few studies on the relationship between the time of thermal breakthrough and its influencing factors.Therefore,in order to make effective use of underground thermal energy resources,this paper studies the seepage heat transfer characteristics of aquifers under different geological conditions in combination with the situation of groundwater source heat pump water injection,and discusses the construction and optimization of groundwater source heat pump system.This paper analyzes the influence of porous media characteristics of aquifer on the characteristics of groundwater water intake and heat transfer under pumping and irrigation flow by building the mathematical model of groundwater seepage and heat transfer.Based on the COMSOL software,the distribution of aquifer temperature field under different conditions was simulated,and the effect of the optimized operation mode of the groundwater source heat pump system was discussed,and the operation management mode of "large temperature difference and small flow" was proposed and verified to significantly improve the system's water intake and heat transfer capacity.The influence of different permeability coefficient on the heat transfer capacity of aquifer is great.Different values of permeability coefficient of sand soil with permeability coefficient greater than 20m/d have obvious influence on seepage heat transfer.Especially when the hydraulic gradient is large,the influence of different permeability coefficients on the seepage field and temperature field is great.Therefore,in practical investigation,for sand with large particle size,the permeability coefficient should be measured to evaluate the seepage heat transfer capacity of the aquifer.For sand soil with permeability coefficient less than 5m/s,such as fine sand or sand with smaller particle size,the seepage heat transfer capacity of an aquifer can be estimated by consulting the data and taking the average value of the permeability coefficient of this type of sand soil.It is not necessary to measure the exact permeability coefficient by experiment.The conclusion can be used to evaluate the heat transfer capacity of aquifer in engineering application.In addition,in order to solve the problem of low efficiency after the development and construction of groundwater source heat pumps,the simulation of this study verified the importance of the operation management mode of "large temperature difference and small flow" in improving the system's water intake and heat transfer.This operation management mode can not only reduce the pressure of water pump operation,but also effectively avoid the occurrence of thermal penetrating phenomenon.Moreover,this operation management mode can effectively make up for the problems of low permeability coefficient and insufficient water volume in the regional aquifer.In the optimization transformation of traditional groundwater source heat pumps,the system can be optimized by adjusting the operation mode of "large temperature difference and small flow rate".