The Use of an Ejector as a Refrigerant Expander

One of the thermodynamic losses in the vapor-compression retr1geration cycle is the throttllng process in the expansion valve. It work is extracted from the refr1gerant during the expansion process, the efficiency of the cycle is swnificantly 1mproved. It 1s proposed that the high-pressure retngerant be used as the motive fluid of a Jet ejector. Instead of extract1ng mechanical work from the expanding refrigerant, 1ts kinetic energy is used to partially compress the saturated vapor leaving the evaporator, increas1ng the enthalpy change in the evaporator and reduc1ng the load on the compressor. A first-order analysis of the cycle performance shows sign1ficant 1ncrease in coeffic1ent of performance and decrease 1n compressor displacement relative to a standard vapor-compresslon cycle. The analysis shows much greater performance changes tor some refrigerants than for others, 1ndicating a potential impact on the selection of new, non-CFC refrigerants. COP h p r s u X q Coetficlent of Performance specific enthalpy pressure motive flow/total flow specific entropy veloc1ty qua.l1ty efficiency IIOIIENCLATURE d tc ge m n s Subscripts: diffuser outlet condenser saturated l1quid evaporator saturated vapor mixing section outlet motive nozzle outlet suction nozzle outlet