Turbulence modeling of a single-phase R134a supersonic ejector. Part 2: Local flow structure and exergy analysis

• A supersonic single-phase ejector working with R134a is investigated numerically.
• The low-Re k–ω SST model predicts well the ejector operation curve.
• The oblique shock train moves downstream with increasing outlet pressure.
• Assumptions usually made by 1D thermodynamic models have been checked carefully.
• The ejector exergy efficiency is about 80% for all operating points.

The present work is the second part of a numerical analysis of a supersonic ejector in single-phase conditions using R134a as the working fluid. In Part 1, a numerical benchmark of some thermodynamic and two-equation turbulence models has been carried out to highlight the numerical model offering the best compromise between accuracy and calculation cost. The validation was achieved by comparing the predicted entrainment ratio with the experimental data of Garcia del Valle et al. In this part, the ejector performance and local flow features are then investigated by a low-Reynolds number k−ω SST model for a wide range of outlet temperatures. Based on these accurate 2D numerical results, a discussion about the validity of the main assumptions usually made by 1D thermodynamic models is then offered. Finally, an exergy analysis is performed at various characteristic sections of the ejector to determine its global efficiency and shed light on the main sources of losses.