The Influence of Buried Tube Depth and Operational Mode on Heat Exchanger Performance

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. In this paper, 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 operation, buried tube will produce inevitably cold and heat accumulation effect in surronding rock mass, and result in water temperature of buried tube oulet 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.