Numerical study on the structural optimization of R290 two-phase ejector with a non-equilibrium CFD model

Abstract

As one of the key components in the ejector-expansion refrigeration system, the operating characteristic of the ejector directly affects the performance of the refrigeration system. In this paper, the internal flow characteristic of R290 two-phase ejector under different structural parameters, including the nozzle outlet diameter, the nozzle diffuser length, the converging angle of the suction chamber, and the length of the ejector diffuser, were analyzed by non-equilibrium CFD method, and the corresponding structural optimization scheme was proposed. Numerical simulation results showed that the length of the nozzle divergent section and the suction chamber's converging angle had little influence on the performance of the ejector. The nozzle outlet diameter has a significant impact on the performance of the ejector. Meanwhile, within the range of nozzle outlet diameters and length of the ejector diffuser studied, the ejector performance increased first and then decreased. In addition, it was found that the vortex flow generated by the fluid inside the suction chamber was the main factor affecting the performance of the ejector. This paper proposed a curved wall of the suction chamber of optimized ejectors. The result showed that the vortex flow area of the optimized ejector was effectively reduced, and the entrainment ratio and total efficiency of the optimized ejector could be increased by up to 25.6 % and 27.5 % compared to those of the baseline ejector.