Experimental evaluation of the performance of an ejector for a single compression multi-temperature CO2 refrigeration unit

A novel vapor-compression system concept employing carbon dioxide as therefrigerant is proposed to serve the needs of a typical medium-sizerefrigerated truck used for multi-temperature (MT and LT) goodsdelivery. The system design is based on the implementation of an ejectoras the only component increasing the refrigerant pressure from the LTevaporation pressure to the MT evaporation pressure, thus allowing therealization of a unit providing cooling effect at two differenttemperature levels with only one stage of compression. The ejector wasexperimentally tested in order to evaluate its ability to effectivelyentrain mass flow rate from very low pressure conditions at the suctionnozzle, corresponding to the LT evaporator outlet conditions. Inaddition, a simple preliminary thermodynamic evaluation of theperformance of the refrigerating unit at -25 degrees C LT saturationtemperature and 35 degrees C gas cooler outlet temperature is conducted.