Utilization of mine waste heat in phase change rechargeable battery

Abstract

Mine geothermal energy has been recognized as “heat hazard”, which is harmful to the health of miners and causes disasters. In order to realize the transformation of mine geothermal energy and waste heat from “hazard/waste” into “treasure”, this paper analyzes the distribution characteristics and genesis of mine geothermal energy with the field geothermal temperature monitoring data, evaluates geothermal reserves, and reveals the mutual influencing mechanism of stratified exploitation of two-layer geothermal reservoir and the law of thermal energy conduction and evolution in the stope of geothermal-coal synergetic mining (GE-COSM), using numerical models verified by experiments. In the end, the improvement effect of mine waste heat on the development potential of geothermal-coal mine (G-CM) was analyzed. The result shows that: The present geothermal field distribution characteristics of Anju Mine are high in the north and low in the south, high in the east and low in the west. There are two layers of zoned reservoir, with the temperatures of 43 °C and 54 °C respectively, the average heat flow value 70.1 mW/m2 and 80.9 mW/m2 respectively, and the geothermal water type SO42--Na+·Ca2+. The simultaneous exploitation of the two geothermal reservoirs will form a Coal-Austria geothermal reservoir joint influence area(C-Area) with lower temperature, which reduces the harm of “heat hazard” to miners. But the phase change heat storage function of functional cemented paste backfill material for phase change heat storage (F-CBM) is not fully utilized in the late stage of geothermal exploitation. The mine generates 4.6 × 1011 J of waste heat per day, and according to the type of heat source of mine waste heat can be continuously “heat charging” for a conventional backfill working face. Moreover, under the action of high temperature surrounding rock, the thermal energy recovery rate is greater than 1, and under the action of “heat charging”, the average maximum value of solid phase ratio is greater than 70 %. Therefore, the phase change rechargeable battery mode creatively proposed by this paper is significantly better than the traditional rock layer heat storage mode and is worth vigorously popularizing.