The use of carbon dioxide (CO_2), as a working fluid for large refrigeration systems, has grown tremendouslyin recent years. Factors such as its low cost, easy accessibility and environmentally friendly characteristicscompared to HFCs and HCFCs, has made CO_2 a viable alternative. To efficiently operate with CO_2, thethermodynamic cycle needs high-pressure levels that can easily exceed the critical point due to the lowcritical temperature. By replacing conventional expansion valves with ejectors, the thermodynamic losses ofthe high-pressure throttling are mitigated, and the overall system performance is improved. To design andefficiently control the whole cycle, a thorough comprehension of the ejector fluid dynamics is mandatory. Inthis work, Computational Fluid Dynamics (CFD) is used to thoroughly investigate such a device. Theemployed CFD solver uses a modified form of the Homogenous Relaxation Model (HRM) to deal with twophaseflows in a non-thermodynamic equilibrium state, per Colarossi et al. (2012). Preliminary numericalresults for an ejector in supermarket refrigeration system operating conditions are presented and discussed.
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