Derivation and comparison of thermodynamic characteristics of endoreversible aircraft environmental control systems

An aircraft environmental control system (ECS) ensures a healthy and thermally comfortable environment for passengers and has a significant influence on the energy consumption of the aircraft. Existing simulations rely on complex iterations to determine the thermodynamic performance of ECSs under specific conditions, yielding results that are not universal. Therefore, to avoid repeated modeling and calculations, analytical solutions for the coefficient of performance (COP) of the ECS were derived based on the endoreversible thermodynamic analysis model. In this study, the solutions for the COPs of five types of ECSs were obtained. We found that each type of ECS had a unique solution for COP, reflecting the thermodynamic characteristics of the system. Results showed that the high-pressure water removal module does not affect the thermal performance of the ECS under dry conditions. The thermal performances of the three-wheel and four-wheel ECS were the same. The effects of different flight conditions, pressure ratio of the compressors, and heat exchanger effectiveness on the COP of the ECSs were also analyzed, reflecting the external and internal responses of the ECSs. The solutions reveal the mechanism of thermal power conversion in the ECS, which is helpful for component selection, ECS integration, and aircraft conceptual design.