To provide an underground heat exchanger in which a cross-sectional shape of a heat medium pipe is formed into a long circular shape to secure a surface area of the heat medium pipe and a contact area between the heat medium pipe and a housing, thereby having an improved efficiency of heat exchanging.
The underground heat exchanger includes: a first cylindrical housing 11; a second cylindrical housing 12 installed on a radial outside of the first cylindrical housing 11; and a first heat medium pipe 21 disposed between the first cylindrical housing 11 and the second cylindrical housing 12, in which a cross-sectional shape perpendicular to a lengthwise direction is a long circular shape extending along a lengthwise direction of the first cylindrical housing 11.
Kato Kazunori
Hiroshi Fukuda