Waste heat recovery from diesel generator jacket water for mine intake air pre-heating in cold climates: A numerical study

Underground mining operations in cold climates such as Sweden and Canada need to protect the shafts and mechanical components from freezing by heating the intake air to up-freezing temperature. The substantial flow rate of air required by these mines at freezing temperatures during the long winters in such climates results in a very high heating demand that is conventionally satisfied with fossil fuel burners (i.e. natural gas and propane). Using fossil fuels for pre-conditioning the intake air leads to higher operating costs along with a larger carbon footprint. Contemporary mining operations are undergoing a necessary change in deploying clean and low-cost energy solutions to compensate their energy footprints as the global consensus regarding the clean energy solidifies. Waste heat recovery is among the reliable alternatives for fossil fuels with enormous potential. Jacket water of the diesel generators installed in the mine, due to its extremely high thermal energy, is one of the high-grade waste heat sources in underground mines. The present paper aims to investigate the feasibility of implementing a jacket water heat recovery system at underground mining operations with a numerical heat transfer model. A typical off-grid remote mine in Canada has been investigated. The case study has demonstrated that the proposed system can save a significant portion of intake air heating costs. The performance of the proposed system has also been supported by a meticulous parametric study on the intake air flow rate and effectiveness of the heat exchangers.