Test and Analysis of U-Tube Heat Exchangers Ground-Source Heat Pump System in Summer

The design of the ground heat exchanges is the key of the GSHP system. Borehole depth,flow velocity,soil initial temperature, operating mode , etc. are the main factors that affect the performance of ground heat exchanges. Tests the summer operating mode of the ground source heat pump system with different deep buried U-tube ground heat exchangers (60m,90m) built up in Shanghai district. The paper presented the soil initial temperature distribution and the mean heat transfer capacity per unit borehole depth under the different operation modes and different flow velocity .Results show that the increase in flow velocity is not simply raise the heat transfer capacity per unit borehole depth, there is a reasonable range for flow velocity within the U-tube.