Research on ground-coupled heat exchangers

Ground source heat pump (GSHP) has been considered as one of the most promising low-carbon technologies for building heating, ventilation and air conditioning (HVAC) applications at present. Since a GSHP relies heavily on the performance of ground-coupled heat exchangers (GCHEs), this paper was focused on GCHEs key technical issues and presented results of experimental investigation and computer simulation. A test rig was built to carry out the thermal response test, and test results for a double-U tube GCHE were analyzed. Software Fluent was used to simulate the GCHEs and simulation models were created for single-U-type and double-U-type GCHEs for the depths of 50, 60 and 70 m. Based on dissipation simulation it was found that using a double-U-type GCHE to replace a single-U-type GCHE can gain an increase in the total heat dissipation capacity by over 50%, with a drawback of 20% reduction of circulating water temperature difference. The borehole depth of a GCHE can be increased to meet the requirement of a larger heat dissipation capacity. The specific heat dissipation rate will drop about 6% for every 10 m increase in borehole depth. This study is useful for design GCHEs and the ground-coupled heat pump technology. Copyright The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.