compressed air

Applied Thermal Engineering

Compressed air energy storage (CAES) systems usually operate under off-design conditions due to load fluctuations, environmental factors, and performance characteristics of the system. Thus, to improve design and operation characteristics, it is important to study off-design performance of CAES systems. The compression process plays an important role in CAES systems. In this paper, we discuss the methodology for modeling off-design operation of a multistage compression process with intercooling of the most promising adiabatic CAES (A-CAES) system. The off-design performances under two proposed kinds of operating regulations are analyzed and compared. These two operating regulations are equal-power-ratio regulation (EPR) and optimizing variable inlet guide vane rotation angle (OVRA) (optimizing all stages simultaneously) regulation. Correlation between parameters such as total power consumption ratio, exergy efficiency, hot water temperature versus mass flow rate ratio, and back pressure is revealed in depth. Based on this research, the optimal operation laws, including pressure ratio distribution and efficiency distribution among all stages, are obtained, and it is found that the primary optimum principle is to enhance the isentropic efficiencies of low-pressure stages to approach design point. Finally, the optimized regulating law for the inlet guide vane rotation angles of the 4 stages is revealed. This study provides strong support for the design, operation, and control of CAES systems.

Off-design performance and an optimal operation strategy for the multistage compression process in adiabatic compressed air energy storage systems