Performance of a direct expansion ground-source heat pump for air conditioning

In this study, the cooling and heating performances of a direct expansion ground-source heat pump (GSHP) was investigated using three sets of 30 m ground-source heat exchangers, each comprising three branched copper pipes connected in parallel to the heat collection and heat dissipation parts. The changes in the performance over long-term operation was also examined. Cooling and heating experiments were conducted using an air conditioning area of 50 m2, a GSHP cooling output of 6.8 kW, and a heating output of 8.8 kW. The cooling operation was performed at a set room temperature of 27 °C under two time constraints of 9 h and 180 h, whereas the heating operation was performed at a set room temperature of 20 °C under two time constraints of 7 h and 168 h. The coefficient of performance (COP) was calculated for performance evaluation and the result of the experiments was as follows: during the cooling operational period, the average output power was 5.26 kW, average power consumption was 0.46 kW, and COP was 11.5; during the heating operational period, the average output power was 4.84 kW, average power consumption was 0.74 kW, and COP was 6.62.