Experimental study on operative characteristics of ground-source heat pump systems for hot water in Pearl River Delta region

Establishes an experiment platform on the basis of an existing U-tube ground-source heat pump system for hot water. Studies the startup characteristics and coefficient of heating performance of ground-source heat pump, temperature recovery of circulating water in buried pipe, heat transfer per unit borehole depth and thermal influence radius of ground heat exchanger under different operation conditions in this region. The results show that the period from starting the ground-source heat pump to stable heat transfer is 6 to 9 hours; the average of COP is 3.47 and 3.56 in continuous and intermittent conditions respectively; heat transfer per unit borehole depth in the two test wells in the intermittent operation condition is increased by 6.6% and 9.4% respectively compared to that in the continuous condition; the thermal influence radius of the two U-tube ground exchangers within 48 h is between 0.5 m and 1.0 m.