Study on Air+Ground Source Hybrid Air-Conditioning System

－1st Report: Field Test of the Hybrid System－

Abstract

The spread of ground source heat pump system (GSHP) in Japan is delayed due to high installation cost compared with airsource vapor compression heat pump system. A new air + ground source hybrid heat pump system whose outside air heat exchanger and ground source heat exchanger are connected in series was suggested in this study. The installation cost of this system can be reduced by reducing boring length for setting ground source heat exchanger and by reducing development cost by using commercial air source heat pump system. However, the performance of the hybrid system seems to be lower than ground source heat pump system due to using air heat source. Therefore, evaluation of the system is required regarding cost performance. This study deals with field test, numerical simulation and estimation of cost performance of the hybrid system. This paper is mentioned about the results of field test of the hybrid system as the 1st report. The results show that this hybrid system can be driven using 70% reduced borehole length compared with the general GSHP system. However, the performance of the hybrid system is lower than expectations due to using control system of commercial air source HP.