Simulation And Experiment On The Thermal Performance Of Ground Coupled Heat Exchanger

Ground heat pump system is one of the most important technology in the field of HVAC,which could be used for heating, cooling and hot water supplying. It is regarded as a newtechnology of high development potential, with the advantages of energy saving and higherefficiency. By laying of underground heat exchangers, ground heat pump system could extractthe energy storing in the soil. So that the heat exchanged capacity of the heat exchangers andthe temperature in the soil are very important for the ground heat pump system.First of all, this paper made a study on the heat transfer manner of the heat exchangersthrough theoretical analysis. Mathematical and physical model of a vertical U-tube is builtbased on cylindrical heat source theory, in which some factors are taken account. The heattransfer control equations are solved by the finite volume method, and then the outlettemperature of heat exchanger and the temperature of the soil are achieved. Secondly, anexperimental facility in situ and a TRNSYS simulation platform are built to test the outlettemperature of heat exchanger and the temperature of the soil. The results of these twomanners are consistent with each other, which proves that both of the manners are credible.Then the experimental and TRNSYS simulation results are used to verified the model of thevertical U-tube heat exchanger, the relative errors between the experimental results andsimulations results are within8.4%, it is accepted in the scope of calculation accuracy. Finally，the model is used to simulation the heat exchanged capacity of the heat exchangers, the outlettemperature of the heat exchanger and the temperature in the soil under some differentconditions, which make a contribution to the design ang engineering practice of ground heatpump systems.