## 1 Introduction
[25] developed a numerical simulation for the coupled thermo-mechanical performance of a lined rock cavern for CAES systems. An air pressure range from 4.5 to 6.9 MPa was considered for 100 cycles with a thickness of concrete lining of 0 and 0.1 m. They concluded that significant air temperature fluctuation was observed in sealing layer and concrete lining and no fluctuation occurred in the rock mass. An analytical study was proposed to estimate the geomechanical performance caused by air temperature and pressure variations in CAES systems [26]. [PERSON] et al. [27] studied the thermo-mechanical responses of CAES systems in rock salt caverns. They concluded that the stability of the salt cavern is affected by the internal operating conditions with the air temperature increasing the volume convergence. [PERSON] et al. [28] carried out a failure study for gas storage by thermo-mechanical modelling in salt caverns. The results showed an affected area by the air and temperature operating conditions up to 10 m in the rock mass from the cavern walls. Round trip efficiencies between 70.5 and 75.1% were estimated by [PERSON] et al. [29] in A-CAES systems for continuous operation with packed bed thermal energy storage. The thermodynamic and geomechanical performance was studied by [PERSON] et al. [30] in lined rock caverns. They found that 97% of the thermal energy injected in the charge period could be recovered in the discharge period. [PERSON] et al. [31] designed a new CAES systems with constant gas pressure and temperature in closed coal mines. A power output of 18 MW and a generating time of 1.76 h were obtained for a mine tunnel with 10,000 m\({}^{3}\) of volume at 500 m depth. The ADELE project was studied in Germany to install an A-CAES plant with a storage capacity of 360 MWh and output power of 90 MW [2]. In this paper, abandoned mines are proposed as underground reservoirs for large scale energy storage systems. A 200 m\({}^{3}\) tunnel in an abandoned coal mine was investigated as compressed air reservoir for A-CAES plants, where the ambient air is stored at high pressure. The thermodynamic response of A-CAES reservoirs was analyzed considering three solids around the pressurized air: a 20 mm thick sealing layer, a 35 cm thick concrete lining, and a 2.5 m thick sandstone rock mass. One-dimensional analytical and three-dimensional CFD numerical models were conducted considering fiber-reinforced plastic (FRP) and steel as sealing layers and a typical operational pressure from 5 to 8 MPa. In the analytical model, air mass flow rates of 0.22 and \(-\)0.45 kg s\({}^{-1}\) have been considered for 30 cycles of compression and decompression, respectively. To reduce the computational time, the numerical simulation has been conducted for five cycles with air mass flow rates of 50 and \(-\)75 kg s\({}^{-1}\). The air temperature and pressure fluctuations were estimated in the simulations. The temperature and the heat flux were also analyzed on the contact surfaces of the solids considering both FRP and steel sealing layers and the heat convection from the air to the sealing layers was calculated. Finally, the energy balance through the sealing layer was obtained during air charging and discharging.