Performance analysis of a coal mine air supply system based on a multienergy complementary energy supply system

Mine ventilation air heating in severely cold regions is commonly supplied by coal-fired boilers, leading to high energy use and environmental impacts. This study proposes a multienergy complementary energy supply system integrating air-source heat pumps (ASHPs), a cascade water-source heat pump, and thermal energy storage to ensure reliable shaft anti-freezing (3°C) and flexible operation under time-of-use electricity pricing. A dynamic TRNSYS model was developed for a coal mine in Wuhai City, Inner Mongolia, and validated against measured data with an average relative error of 7.57%. Comparative simulations were conducted to determine the operating applicability of a standalone ASHP and the proposed composite system under varying ambient temperatures and storage temperature levels. Results indicate that a standalone ASHP is preferable under mild outdoor conditions and low heating temperature requirements, whereas the composite system is recommended for extreme cold conditions (below −14°C) and higher-grade heat demands, delivering improved stability and a maximum system coefficient of performance increase of 13.18%. By combining thermal storage with time-of-use electricity pricing, operating costs can be reduced by 23%–70%, while fossil fuel consumption and carbon emissions are reduced by ~76% and 58%, respectively. The proposed system provides practical guidance for selecting operating modes and retrofitting mine ventilation heating systems in severely cold regions.