Characteristics of geothermal energy obtained from a deep well in the coldest provincial capital of China

The abundantly available renewable geothermal energy resources play an important role in people's life in the applications of hot water supply, greenhouse heating, air conditioning, electricity generating, breeding, incubating, drying, irrigating, refrigeration, and so on. This study investigated the characteristics of geothermal energy obtained from a 100 m deep well in Harbin, the coldest provincial capital of China. The effects of air temperature, wind scale, and fluid velocity were also studied. When the air temperature varied in the range of -21.76 ~ -15.27 °C and the wind scale was in the range of 2-5, the tube and soil temperatures varied in the ranges of -1.3 ~ 1.8, 3.9 ~ 4.6, 6.6 ~ 7.7, 7.7-8.7, 8.9 ~ 9.8, 10.4 ~ 11.3, 11.9 ~ 13.1, and 13.4 ~ 14.8 °C for the well depths of 1, 5, 10, 20, 40, 60, 80, and 100 m, respectively. Ambient conditions had significant effect on the soil temperature above 1 m whereas nearly no effect on the soil temperature under 5 m. When the fluid velocities were between 0.09 m/s and 0.18 m/s, the tube temperatures reached stable within one hour, and the fluid velocity had slight effect on the tube temperatures. The results obtained from this study offer precious geothermal energy information for the cold regions of China and also the whole world.