22 May 2008

GROUND TEMPERATURE AND MOISTURE CONTENT SURROUNDING HORIZONTAL HEAT PUMP COLLECTORS IN A MARITIME CLIMATE REGION


Numerous studies have explored the nature of thermal energy transfer between
heat pump collectors and the surrounding ground. These have been mainly conducted in
continental climate regions and the findings have recommended that horizontal collectors be
submerged at depths of up to 2m to avoid the cooling effects of low temperatures at the
ground surface-atmosphere interface. However, shallower arrays are used in maritime
climate regions where potential exists for the climate to aid thermal transfer to the collector.
This paper reports initial findings of a joint experimental measurement and numerical
simulation study undertaken to investigate this potential. The 430m2 horizontal collector
used was connected to a 15kW heat pump. Presented results show the combined effect of
heat pump operation and climate on ground temperature and moisture content about the
collector. A simulation model capable of predicting climate induced ground soil temperature
and moisture fluctuations to a depth of 2m with a high degree of accuracy is also presented.