Analytical and numerical modeling of a vapor jet refrigeration cycle for vehicle air conditioning

The idea of replacing vapor jet refrigeration system instead of conventional vehicle cooling system is the main goal of a comprehensive study. First part of this study is reported in this paper. The ejector is the heart of these systems, and its optimum design is critically important to the coefficient of performance (COP) of the whole system. Firstly, a basic analytical model for calculation of the ejector optimum geometry for a widerange of operating conditions is derived by a onedimensional model. This theoretical model is complex, with coupled equations based on fluid dynamics principles and conservation laws. Also, they require the physical properties of the fluids and iterative computations. Secondly, a computer code has been developed. R- 134a is considered as the working fluid and a rated cooling capacity of 2.5 kW. Influences of four majorparameters which are area ratio, generator, condenser, and evaporator temperatures, are discussed on both ejector entrainment ratio (w ) and COP. Also, the maximum value of w has been estimated by a correlation of the effective parameters in a nondimensional form.Results show the model can be used as a basic tool in ejector design for vehicle air conditioning.

کلیدواژه ها:

refrigeration ، ejector ، optimum design ، vehicle