Modeling of expansion valve for automotive air conditioning systems
Expansion device scales back the pressure and regulates the refrigerant flow into the low aspect evaporator at intervals of the vapor compression system. A model of the expansion device is crucial to simulate the complete refrigeration system; it additionally might be used as a virtual detector to estimate the upstream pressure as a part of the automatic diagnostic system. Modelling of the expansion device is carried out by many researchers and, in turn, dissimilar models are provided. The objectives of this study are to analyze and provide a review of modeling tools for the expansion valve of automotive air conditioning systems. The review presents almost all early mathematical models presented in literature with describing each model in details and the conditions/limitations of each one. Thought this review study of such issue, which has not been introduced previously according to the best of author knowledge, is very valuable for any researcher in automotive air conditioning systems. Early studies introduced different models for the expansion valve based on the different design, such as electronic expansion valve (EEV), electrical expansion valve (EXV), and regulator expansion valve (TXV). The modeling steps, in general, of any valve are carried out via calculation of the porta constant and discharge coefficient formulations. Then, the mass flow, density, and the pressure distinction are all defined via experimintal or numerical research. Finally, individual elements of each valve style including different parameters for operation and behavior are reflected in the mathematical model.
Keywords- Expansion valve; mass flow characteristics; air conditioning; automotive; review; modeling