CFD MODELING OF HIGH-SPEED CONDENSATION IN SUPERSONIC NOZZLES, PART II: R134a

The present work performs CFD simulations of condensing flows inside a Laval nozzle. The intended application is the numerical modeling of supersonic ejectors with different working fluids: R718 (water) and R134a. Both these refrigerants are “wet” fluids, and their expansion inside supersonic nozzles can lead to non-equilibrium condensation that alters the pressure and Mach profiles, and induces thermodynamic losses. The numerical analysis of these phenomena requires modeling the microscopic behavior of the fluid where properties must be reproduced with a high level of fidelity. In part I of this work, the accuracy of the “wet steam” model available in the commercial CFD software was evaluated with a comparison with experimental results. In part II, the same wet steam model is adapted to reproduce the properties of R134a. The accuracy of this model is assessed though a comparison with the NIST REFPROPOP database as well as experimental results collected from a small-scale prototype ejector chiller.