Collaborative Optimization of Stope Cooling and Geothermal Energy Exploitation for Backfill Embedded Heat Exchanger

Backfillembedded heat exchanger (BEHE) are used for stope cooling during the mining process and for geothermal energy recovery during the long-term heat extraction stage. This study develops a three-dimensional BEHE model to optimize the pipe arrangement, considering both the immediate requirements of stope cooling and the long-term objectives of geothermal energy exploitation. To evaluate the effects of geothermal energy extraction and stope cooling, heat extraction per meter and average temperature in the stope area are used as criterion parameters. The results indicate that the cooling efficiency is positively correlated with the number of pipe layers and pipe diameter, while it is negatively correlated with pipe spacing, interlayer spacing, and the distance from the bottom of the backfill-embedded heat exchanger (BEHE) to the cold radiation surface. Geothermal energy extraction, on the other hand, is positively correlated with the number of pipe layers, interlayer spacing, and the distance from the bottom of the BEHE to the cold radiation surface. Considering both objectives, the optimal pipe arrangement is determined to be PLS = 1.0 m, S = 500 mm, F = 3, D = 0.05 m, and DN = 50 mm. Additionally, based on a comprehensive analysis of extensive calculation results, an empirical correlation for heat extraction per meter as a function of pipe arrangement parameters was derived.