Compressed air-flow and physical property in mine tunnels during cyclic charging and discharging

This paper utilizes CFD methods to simulate high pressure gas charging and dis?charging in a horseshoe-shaped tunnel. Simulation results reveal linear pressure and temperature variations during charging and discharging cycles, with stabi?lized trends after several cycles. The evolution of air physical properties such as density, viscosity, thermal conductivity, and specific heat capacity within the tunnel is also analyzed. The air density increases with pressure and decreases with tem?perature, stabilizing after several cycles. Viscosity and thermal conductivity exhibit similar trends to temperature, with minor variations throughout the cycle. Specific heat capacity increases during gas charging, remains constant during storage, and decreases during gas release. The study contributes to the optimization of CAES systems in abandoned coal mines by providing detailed insights into air-flow and heat transfer characteristics.