Numerical and experimental study of geothermal heat extraction from backfilled mine stopes

Abstract

Underground mines are valuable sources of geothermal energy. The present study evaluates the possibility of the novel idea of installing geothermal heat exchange tubes in backfilled mine stopes prior to backfill placement for the purpose of geothermal heat extraction. It aims to understand the heat transfer phenomenon that takes place during heat extraction from underground backfilled stopes. To investigate the feasibility of the novel technique of heat extraction from backfilled mine stopes, numerical and experimental heat transfer studies are conducted. To assess the performance of a stope-coupled geothermal heat exchanger system, a numerical model is developed. The model is capable of considering the effect of heat conduction as well as natural convection. The results of the developed model are compared with those from existing ground-coupled heat exchanger models. To further validate the developed numerical model, a series of experimental tests are conducted using a small-scale laboratory test setup built for this purpose. By introducing information gathered from a number of Canadian mines into the developed heat transfer model, effects of hydraulic conductivity, thermal conductivity, rate of heat extraction and arrangement of heat exchanger tubes are investigated.