Suitability evaluation and optimization design of the shallow geothermal energy underground heat exchange system—Taking Zhengzhou shallow geothermal energy demonstration project as an example

Abstract:

The development and utilization of geothermal resources can play a positive role in reducing CO₂ emissions and restraining global climate change. Underground heat transfer of shallow geothermal energy mainly includes the groundwater well system and the underground buried pipe system. Their common advantages are high energy utilization coefficient， safety and stability， zero pollution discharge， etc.； however it has advantages and disadvantages in heat exchange efficiency， development and utilization conditions， space occupation and so on. This paper describes the suitability evaluation index of the shallow geothermal energy underground heat exchange system； and in the execution of the shallow geothermal energy demonstration project in Zhengzhou， field tests such as pumping and reinjection test， geotechnical thermophysical parameter test and formation thermal response test were carried out respectively， and the suitability of two heat exchange modes of shallow geothermal energy is analyzed and compared， It is concluded that the rock and soil in the construction area has high thermal conductivity and volume specific heat capacity， which is conducive to heat conduction and maintenance； but the buried depth of the regional water level is shallow， the reinjection capacity is only 107.37m³/d， and is poor. Through comparison， the underground buried pipe heat exchange system which is more suitable for the development and utilization of shallow geothermal energy in the construction area has been finally optimized and selected for development.