Energy and exergy analysis of two modified adiabatic compressed air energy storage (A-CAES) system for cogeneration of power and cooling on the base of volatile fluid

A novel isobaric adiabatic compressed air energy storage (IA-CAES) system was proposed based on the volatile fluid in our previous work. At the same time, a large amount of waste heat should be employed, which may restrict its applications. Two modified A-CAES (configuration 1&2) without using waste heat are proposed in this work. The volatile fluid has two functions: driving the air out of storage vessels and evaporating in a heat exchanger to generate cooling energy. Carbon dioxide (CO₂) is selected as the volatile fluid due to its environmentally properties and high saturation pressure at ambient temperature. The thermodynamic analysis is evaluated by using a steady-state mathematical model and thermodynamic laws. The calculation results show the configuration 1 has the same round trip efficiency (RTE) as conventional A-CAES, while 36.59% additional cooling energy can be obtained, and the total exergy efficiency (TEE) improves by more than 2%. Moreover, configuration 1 saves nearly 35% of the total volume of the air storage unit. Compared with conventional A-CAES, configuration 2 has obtained 42.71% additional cooling energy, the RTE and TEE improve 0.14% and 2.83%, respectively. Meanwhile, parametric analyses are also carried out to evaluate the effects of several critical parameters on the system performance of two modified A-CAES systems.