The study on heat exchange performance influential factors of ground heat pump

Ground coupled heat pump has become an attractively alternative way to cool and heat buildings in China, however, in practice their operation and effect especially on the performance of heat exchanger are unsatisfied, which is greatly influenced by different geologic structure in different district, moreover, few literature on field test could be found to support the design and development of ground coupled heat pump in Chongqing district. In order to improve the performance of ground heat pump in Chongqing, the influence of buried tube depth and operational mode on heat exchange performance were studied by experiment. The experimental results showed that intermittent operation mode will help to improve energy efficiency of buried tube and improve the host operating efficiency. In the long term of operation, buried tube will produce inevitably cold and heat accumulation effect in surrounding rock mass and result in water temperature of buried tube outlet rising (summer) or decreasing (winter), cooling temperature of the condenser (summer) increasing, evaporation temperature of evaporator decreasing (winter), then the operating efficiency of host machine in the actual operation would be decreased. It is suggested that ground source heat pump system with auxiliary cold/hot equipment should be considered in practice.