Optimized Refrigerant Flow Rate and Dimensions of the Ejector Employed in a Modified Ejector Vapor Compression System

Abstract

This paper presents the analysis of a modified vapor compression cooling system which uses an ejector as an expansion device. Expanding refrigerant in an ejector enhances the refrigeration effect and reduces compressor work. Therefore, it yields a better coefficient of performance. Thermodynamic analysis of a constant area ejector model has been done to obtain primary dimensions of the ejector for given condenser and evaporator temperature and cooling capacity. The proposed model has been used to design the ejector for three refrigerants; R134a, R152a and R1234yf. The refrigerant flow rate and the diameters at various sections of the ejector have been obtained by doing numerical modeling in Engineering Equation Solver (EES). Refrigerant R1234yf demanded the highest diameter requirements at a fixed 5∘C evaporator temperature and 40∘C condenser temperature for a given range of cooling load. Both primary and secondary refrigerants flow rates are higher for R1234yf followed by R134a and then R152a.

Vapor Compression Cycle: A State-of-the-Art Review on Cycle Improvements, Water and Other Natural Refrigerants

“…Theoretically, this process should be isenthalpic, meaning enthalpy should be reserved. However, in reality, the expansion process wastes energy that can be recovered by using expanders or ejectors [36].…”