Experimental Study of Heat Exchange in Ground Source Heat Pump with Vertical Pipes
Ground source heat pump systems are widely used as an energy-saving technology in heating and air-conditioning areas. In this paper, the experimental method was applied to analyze and discuss the influential factors of heat exchange in the existing ground source heat pump laboratory. Four types of Utube were buried in sixteen vertical boreholes in this system. The temperatures and flow fluxes of water in pipes were measured in the test. And the heat fluxes per meter of well depth can be calculated. The results show that water flow velocities in pipes have greater influence on heat fluxes per meter in winter or summer operation. But the influence of water temperatures of pipe inlets on the heat fluxes per meter is not very distinct for both winter and summer test. The capacity of heat rejection in summer is higher than that of heat extraction in winter. Dual U-tubes are superior to singular U-tubes, and tubes with big diameters are superior to tubes with small diameters.