Enhanced Phase Change Heat Storage of Layered Backfill Body under Different Boundary Conditions

In view of the high temperature problem faced by mining activities, the coordinated mining of ore deposit and geothermal energy is a solution in line with the concept of green mining. The layered backfill body with finned double-pipe heat exchanger continuously exchanges heat with the surrounding thermal environment, which plays an effective role in gathering geothermal energy. In this paper, the heat storage process of each layered backfill body under different boundary conditions is simulated by Fluent. The results show the heat storage characteristic of layered backfill body can be significantly improved by adding fins to the double-pipe heat exchanger. On the whole, the heat storage effect of bottom layer backfill body (BLBB) is the best. The total heat storage capacity of top layer backfill body (TLBB), middle layer backfill body (MLBB) and BLBB with the finned double-pipe heat exchanger is 666.3 kJ, 662.2 kJ, 1003.0 kJ; 1639.0 kJ, 1760.8 kJ, 1911.2 kJ and 1731.1 kJ, 1953.3 kJ, 1962.8 kJ respectively at 1 h, 8 h and 24 h. This study explores the law of heat storage of layered backfill body under different boundary conditions and also expands the idea for layered backfill body to efficiently accumulate geothermal energy.