農業ハウス空調用地中熱ヒートポンプの実証試験

抄録

Ground source heat pumps (GSHPs) use buried pipes to extract heat from the ground and to release heat to the ground. In a conventional GSHP system, which uses an indirect heat exchange method, vertical systems use two long pipes connected by a U-shaped fitting at the bottom of a hole bored in the ground. In contrast, a GSHP that uses a direct expansion method circulates a mixed refrigerant through the ground loop. In the experiment, the depth of the borehole was 30 m, and the refrigerant was R410A. The heat exchanger of a ready-made air-conditioner was replaced by an underground heat exchanger. The underground heat exchanger consisted of narrow copper tubes inserted into the bottom end of a long pipe filled with water. This paper describes preliminary experimental results of the GSHP that uses the direct expansion method applied as an air conditioning of greenhouse.