Thermal-Stress Response Analysis and Applicability Study of Energy Shafts in Winter

Energy shafts and energy tunnels are a kind of energy conservation and environmental protection underground structures. They can be used as shallow geothermal energy harvesting systems in cold regions. The theoretical research and practical application of energy shafts are still in the initial stage, and there are relatively few related experiments. This paper takes the Shanghai Taihe energy shaft test section in winter as the research background. It numerically analyzes the thermal-force response test of the energy shaft using COMSOL software. And compared with the Beijing Qinghuayuan energy tunnel for applicability evaluation and analysis. The results show that the heat exchange capacity of the Shanghai energy shaft is better than that of the Beijing energy tunnel due to the difference in the geological environment. Meanwhile, the temperature stress generated during heat exchange in Shanghai energy shafts is less than that in Beijing energy tunnels. Therefore, the energy underground structure is more applicable to the Shanghai strata in winter. Based on the thermal results and economic considerations, it is suggested that the inlet fluid velocity of the energy shaft is around 0.6 m/s in winter. The heat transfer tube spacing between 0.2 and 0.3 m can ensure a high heat transfer capacity.