Simulation And Experiment On Thethermal Performance Of U-Type Underground Heat Exchanger

Ground source heat pump which absorbs heat(cold) from the shallow soil is the most friendly to the environment and most effective cooling(heating) mode in the current circumstances. In recent years, people gradually increased the research of heat pump technology, and how to improve the thermal performance of heat exchanger is becoming a research focus.The paper based on the new energy renovation project of southwest university of science and technology. First of all, according to the requirement of the relevant technical specifications, using professional geotechnical t hermal response test instrument, test the single and double U buried tube heat transfer performance. The most commonly used method of slope in engineering is adopted to analyze the test da ta,obtained soil coefficient of thermal conductivity, volumetric heat capacity and the borehole thermal resistance.Then use test measured soil initial temperature, the return water temperature and flow rate of u-type underground heat exchanger, power consu mption and other data to calculate, The results sho wed that double u-type heat exchanger ’s per linear meter in heat and energy efficiency were higher than single u-type.Finally, the numerical simulation method was carried out on the heat transfer performance of the u-type heat exchanger. Inputting test measured thermal physical parameters in the 3d model which is exactly the same as the actual, simulation results are in good agreement with measured test data, verifying the correctness of the model. The influence of the inlet velocity and temperature, the depth of the drilling, backfill materials and the initial soil temperature were obtained by dynamic simulation. Research pointed out that the design of the fluid inlet temperature should be comprehensi ve consideration of the system energy efficiency coefficient and heat transfer, the design flow rate for 0.4~0.6 m/s advisable, drilling depth take 60 m to 100 m deep appropriate, the coefficient of thermal conductivity of backfill materials slight ly greater than that of soil is the best.