Shadowgraph visualization of condensing R134a flow through ejectors
Abstract Accurate simulation of ejector flows has been challenging due to the difficulties in modeling two-phase supersonic flows of fluids other than air or steam at high temperature and pressure conditions. Such modeling is necessary for ejector optimization, but the models currently available have yet to be validated. A transparent ejector test section is designed, fabricated, and operated in an ejector-based chiller loop using R134a as the working fluid. Undistorted visual access allows for detailed shadowgraph visualization of the motive jet in the mixing section at various degrees of condensation. High-speed imaging is used with measured temperatures and pressures at the ejector inlets to validate available analytical and CFD models. It is found that the best modeling techniques assume that the motive flow exits the motive nozzle at full thermodynamic equilibrium, and that the k-e RNG turbulence model in ANSYS FLUENT captures these equilibrium conditions sufficiently.