HEAT EXTRACTION FROM THE GROUND IN A VOLCANIC ZONE USING COPPER WATERHEAT PIPES - EXPERIMENT AND ANALYSIS

This test of the technical feasibility of extracting heat from the ear th of a volcanic zone and delivering it to water-utilizing heat pipes was conducted at Tsukahara Hot Spring in Kyushu, Japan, in July 1992. The temperature distributions of the heat pipes and the surrounding ea rth were analyzed through an equivalent thermal network-a three-dimens ional circuit of thermal resistances and capacitors taking account of the mass transfer-and did not show much agreement with the experimenta l data. The calculated values of the heat transport, taking account of the mass transfer, agreed well with the experimental ones in the stea dy state, assuming the thermal conductivity of the earth. But a discre pancy arose in the unsteady state during startup. There are many probl ems to be overcome in this area of natural phenomena. Earth more than 0.15 m away from the heat pipe was not affected during the test.