Thermodynamic Characteristics and Order Degree of Air Cycle System

An air cycle system (ACS) is the most widely used aircraft environmental control system; it plays an important role in guaranteeing the physical health and thermal comfort of passengers in the cabin. Moreover, an ACS has a considerable impact on the fuel consumption of the aircraft. There is a lack of existing research on the analysis of the operating mechanism of environmental control system. Accordingly, in our study, the thermodynamic characteristics and order degree of the ACS are analyzed based on the endoreversible thermodynamic analysis method (ETM) and the structure entropy method (SEM). Analytic solutions are derived for the thermodynamic characteristics of two types of four-wheel ACSs with high pressure water separation, replacing the complex iteration process in system modelling with algebraic expressions. The correctness of ETM is verified by experimental data. Simultaneously, the order degrees of the two systems are calculated from the perspective of timeliness and quality of information transmission. The results show that the order degree of the split four-wheel ACS is slightly lower than that of the integrated four-wheel ACS, owing to an increase in the uncertainties of the information transmission process. Ultimately, both ETM and SEM are able to provide the theoretical basis for air cycle system design, assessment, and selection.