Development of Ground-Source Heat Pump System Using a Flowing Well

Abstract

For the promotion of ground-source heat pump (GSHP) system in Japan, development of highly efficient system is essential. In this study, GSHP system was developed using a flowing well as a ground heat exchanger (GHE). Flowing well of 250mm diameter and 100m depth was constructed. Slit screens were set at intervals of 61.45 m - 83.45 m and 88.95 m - 99.95 m. 3 sets of 100m double U-tube with 34mm external diameter were installed and connected to 3 heat pumps of 10kW capacity. Performance of the system was evaluated for space-heating and space-cooling of an office building with room area of 126.7 sq. m. Average coefficient of performance (COP) was 4.5 for space-heating and 8.1 for space-cooling. Maximum heat exchange rate was 70.8 W/m for space-heating and 57.6 W/m for space-cooling. It can be said from these data that the system resulted in higher performance. Energy saving and cost reduction can be expected from this kind of system.