| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat collecting pipe for an underground thermal heat pump system of which construction cost is reduced and heat exchange efficiency is improved.SOLUTION: A heat collecting pipe 3 shows a double pipe structure comprising an outer pipe 11 and an inner pipe 12. The outer pipe 11 is made of metal and the inner pipe 12 is made of resin. There is provided a flow passage where after heat medium flows in the inner pipe 12, the heat medium is returned back through a heat collecting passage 13 between the outer pipe 11 and the inner pipe 12. It is satisfactory that a punched hole diameter of a vertical hole 2 so as to cause the heat collecting pipe 3 to be laid in the ground is slightly larger than an outer circumference of the outer pipe 11, and the punched vertical hole 2 can be utilized effectively, so that a construction cost for punching the vertical hole 2 can be reduced. Since metal with higher coefficient of thermal conductivity as compared with that of resin is used as a material for the outer pipe 11, the underground heat is transmitted efficiently to the heat medium and much amount of underground thermal energy can be collected. In turn, since the inner pipe 12 is made of resin, thermal giving or receiving amount between the heat medium flowing in the inner pipe and the heat medium flowing in the heat collecting passage 13 is quite low, it is possible to keep a high heat exchange efficiency. |
