Numerical investigation of R-134a ejector

This paper studies the flow phenomena in the R-134a. In particular, an experimental investigation previously presented has been used as benchmark. In the experimental investigation, three different mixing chamber geometries with the same internal diameter, but different profiles have been tested. The critical conditions and the operating curves have been determined for three mixing chambers, without information of local flow phenomena. This paper deals with the numerical investigation of the local flow field inside the ejectors providing an insight view of the local flow phenomena and providing explanation to the phenomena experimentally observed. The CFD approach is based on a 2D axisymmetric representation of the ejectors, modeling the working fluids as a real gas. The CFD approach has been validated with the experimental data: the operating curves are predicted with relative errors less than 6% (critical mode) and less than 15% (subcritical mode) and local flow phenomena has been investigated.