Analysis on the Performance of Ground Heat Exchangers in Ground Source Heat Pump Systems based on Heat Transfer Enhancements

The heat transfer performance of a ground heat exchanger (GHE) is the key factor in practical operation of a ground source heat pump (GSHP) system. Based on calculation and analysis thermal resistance of vertical GHE, this paper have analyzed main factors, which influence the heat transfer performance of ground heat exchangers’ (GHEs) under different conditions. Combining practical engineering application, approaches of reducing the thermal resistance and enhancing heat transfer of GHE are proposed. For improving heat transfer efficiency and reducing unnecessary heat waste, a new ground heat exchanger with three inlet pipes and one outlet pipe (“3-in&1-out”) is introduced. And according to the results of theoretical calculation and analysis, it is revealed that the heat transfer resistances of the GHE with “3-in&1-out” pipes under variable conditions are always less than that of GHEs with either single U-pipe or double U-pipe. Thus the performance of the GHE with “3-in&1-out” pipes is worthy of further analysis.