Numerical Simulation On Ground Temperature Field Around U-vertical Buried Pipe In Ground Source Heat Pump

Compared to other conventional air condition system,Ground Source Heat Pump air conditioning system utilize soil as cold/heat source, achieve heat transfer between the ground and a working fluid circulating in a closed loop buried in the ground,and then provide the heat and cold energy by heat pump. The GSHP system makes full use of renewable energy and boasts the features of protecting the environment and reducing electric power consumption.It has arousing broad attention and extending application in the world.This thesis establishes the transient heat transfer model of the soil temperature field around a vertical U-tube of ground source heat pump, makes numerical simulation using MATLAB.Based on the simulation of summer condition ,obtains the change rules of buried tube soil temperature with time, the influence of buried tube soil temperature with different ground thermal conductivity, the influence of underground heat exchanger performance with different diameter of embedded pipe and different heat flux, which provides a theoretical reference of the ground-source heat pump system for long-term efficient operation.This simulation results show that, thermal influencing radius of buried tube is gradually enlarged with the heat pump constantly operating, in 10h operating conditions, thermal influencing radius are 0.48m, in 720h operating conditions, thermal influencing radius are 3.5m. In the same time of heat pump operation conditions, as coefficient of thermal conductivity increases, thermal influencing radius also increases. In 10h operating conditions, the temperature of the soil near thetube wall is 23.3℃when coefficient of thermal conductivityλ=1.43W/m·℃,however,when coefficient of thermal conductivityλ=2.43W/m·℃,the temperature of the soil near thetube wall is only 21℃.Thus we can see that good thermal performance backfilling materials help to heat loss.The simulation results of the impact on soil temperature field while 25mm, 32mm, 40mm three different radius show that the greater the radius, the smaller the thermal influencing radius,but the temperature is more and more high, The simulation results of the impact on soil temperature field while Q=35W/m,Q=40W/m,Q=45W/m three different radius show that the greater the radius, the greater the thermal influencing radius,and the temperature is more and more high.Based on the actual engineering projects , With fuel boilers + water chillers ground-source heat pump air conditioning system and air conditioning system as an example.The benefits of the environmental protection and the energy saving of the soil source heat pump air conditioning system have been validated.Differentiates and advantages of the soil source heat pump and the underground water heat pump are given.