CASCADE REFRIGERATION SYSTEM HAVING AT LEAST ONE VARIABLE SPEED COMPRESSOR

摘要

A two-stage cascade refrigeration system 20 is provided having a first refrigeration stage and a second refrigeration stage. The first refrigeration stage defines a first fluid circuit for circulating a first refrigerant 34, and has a first compressor 50, a condenser 54, and a first expansion device 58 that is in fluid communication with the first fluid circuit. The second refrigeration stage defines a second fluid circuit for circulating a second refrigerant 36, with the second refrigeration stage having a second compressor 70, a second expansion device 74, and an evaporator 78 that is in fluid communication with the second fluid circuit. A heat exchanger 44 is in fluid communication with the first and second fluid circuits to exchange heat between the first and second refrigerants 34, 36. At least one of the first or second compressors 50, 70 is a variable speed compressor.