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Optimization of vehicle air conditioning performance at various drive cycles and ambient conditions can be achieved by regulating and distributing the refrigerant flow entering evaporators. Thermostatic expansion valve (TXV), as a flow control device, has been a key element in improving vehicle A/C system operating efficiency and maximizing cooling capacity. Three scenarios are addressed in this paper: (a) the selection of TXVs for a sports utility vehicle (SUV) climate control system, in which a front HVAC unit and an auxiliary HVAC unit are installed; (b) the methodology of developing a goal-oriented criterion for identifying the TXV combination to fulfill the optimization of A/C system performance; and (c) the analytical and experimental evaluation of vehicle cooling performance by varying TXV combinations in various vehicle operating modes.

Traditionally, the preliminary thermal design is behind the mechanical and electrical spacecraft design. Many factors contribute to this including a lack of detailed physical characteristics of the spacecraft and knowledge of the distribution of the thermal loads within the spacecraft. Therefore, the thermal design typically reacts to the mechanical and electrical designs. The thermal analyst gets a configuration and then tries to wrap an acceptable solution around it. The analyst relies on years of experience and trial and error to determine the appropriate design cases and create a thermal design. Depending on the experience level of the engineer, several iterations may be necessary to determine the worst-case design points and an acceptable thermal design.