Performance Evaluation of a Steam Ejector Considering Non-Equilibrium Condensation in Supersonic Flows

Abstract

The present study established an experimental system of steam ejector refrigeration to evaluate the effect of the operating parameters, such as pressure on the diffuser wall and primary and secondary fluid, on the performance and efficiency of the ejector. The model validation of numerical methods was carried out against the experimental data, while the numerical simulation was conducted by utilizing computational fluid dynamics modeling to analyze the internal flow of the ejector. The results indicated that the escalation of the primary steam pressure in the choking position increased the Mach number and entrainment ratio as the flow area of the secondary fluid remained constant. The optimization studies show that the entrainment ratio was maximum when the primary steam pressure was 0.36 MPa. While the pressure was inordinate, the expansion core increased in size and further compressed the flow area of the secondary fluid, hence reducing the entrainment ratio. Subject to the influence of the normal shockwave, the change in back pressure did not alter the entrainment ratio before the critical back pressure. In contrast, the ejector no longer produces the normal shockwave after the critical back pressure; the entrainment ratio, therefore, was reduced with the increase in back pressure.