Carbon Dioxide is one of the most hopeful refrigerants because it has lesser greenhouse effect than all fluorocarbon refrigeration. But when CO2 is used in a refrigeration cycle, the compressor work needed is high and the energy loss at the expansion valve is four times that of the same cycle using refrigerant R-134a. Therefore, this high energy loss diminishes the coefficient of performance of the CO2 refrigeration cycle. We have been researching about a two-phase ejector that recovers expansion work so as it increases the compressor inlet pressure. Consequently, it reduces the compression work and finally it increases the COP of the cycle. This report discusses the mixing characteristics and the pressure recoveries of a carbon dioxide two-phase flow ejector with rectangular cross-section through experiments.

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