Investigation of heating potential and sustainability of medium-deep borehole heat exchanger in severe cold regions

Abstract

Abstract Medium-deep buried pipe heat transfer technology is a way to develop medium-deep geothermal energy by "taking heat without water". Using OpenGeoSys (OGS) software, a comprehensive numerical model of medium-deep buried pipe heat transfer is established using a dual-continuum medium approach and combined with actual engineering data. On this basis, the heat transfer performance and its applicability in the harsh cold region of northern China are investigated. Meanwhile, a sensitivity analysis study on its heat transfer influencing factors and sustainability was conducted. The results of the study show that the medium-deep buried pipe heat transfer technology has excellent heat transfer performance and good applicability and sustainability in the cold region of northern China. The heat transfer performance of buried pipes can be improved by arranging buried pipes in high quality geothermal areas and increasing the flow rate of circulating water, increasing the depth of buried pipes, choosing larger thermal conductivity of inner pipes and backfill materials, etc.; higher circulating water inlet temperature, larger inner and outer pipe diameter ratio and thermal conductivity of inner pipes will reduce the heat transfer effect.