Heat dissipation effect on a borehole heat exchanger coupled with a heat pump

Thermal performance evaluation of a ground-coupled heat exchanger has been undertaken to assess the extent of heat dissipation into the ground and its long term effect on the cooling performance of a heat pump system. Simulation results were compared with operational data over a 3-year period and found to be in good agreement. However the annual average energy being dissipated into the borehole was found to be about 4.5 times more than the amount being extracted thus raising concern about long term effectiveness of the borehole as a heat sink. Even though, there was a slight decline in the energy dissipation rate during the third year, the result does not provide adequate evidence to support creeping soil degradation process in the borehole over such a relatively short period. Since the performance of each ground-coupled heat exchanger appears to be influenced by its location, more research is needed to acquire better and wider understanding of the effect of heat dissipation and soil degradation processes in borehole systems.