A comparative research of two adiabatic compressed air energy storage systems

•A modified adiabatic compressed air energy storage (A-CAES) system is proposed.•The whole processes of the two A-CAES systems are simulated.•Corresponding thermodynamic efficiencies of the two A-CAES systems are determined.•A parametric study of the two A-CAES systems is conducted.•Total exergy efficiency of the modified A-CAES system can be improved about 3%. Adiabatic compressed air energy storage (A-CAES) is regarded as a promising emission-free technology to facilitate the renewable energy integration, when a large amount of renewable energy is abandoned due to the difficulty of integrating fluctuating renewable energy into electricity grid systems all over the world. However, the temperature of discharged air from low pressure turbine is still high in the conventional A-CAES system and a considerable amount of energy is lost. So a modified A-CAES system is proposed to solve this problem in this paper. The proposed modified A-CAES system can simultaneously provide mechanical energy, heating energy and cooling power. This paper aims to make a comparative research of the two A-CAES systems from the technological point of view. The thermodynamic analyses including energy analysis and exergy analysis are evaluated by using steady-state mathematical models and thermodynamic laws. The results show that total exergy efficiency of the modified A-CAES system can be improved nearly 3% compared to the conventional A-CAES system in spite of lower round trip efficiency. Meanwhile, a parametric analysis is also carried out to evaluate the effects of several key parameters on the system performance of the two A-CAES systems.