Patent ID: RE43121

Claim:
A two-stage cascade refrigeration system, comprising: a low stage having a first refrigerant flowing therethrough, the low stage including a compressor having an input and an output, and an evaporator unit having an input operatively connected to the output of the compressor through a stage heat exchanger by an input conduit and an output operatively connected to the input of the compressor by an output conduit , the stage heat exchanger having an upstream side and a downstream side ; a bypass line having an input in communication with the input conduit of the low stage and connected to the low stage input conduit downstream of the stage heat exchanger, an output in communication with the connected to the low stage output conduit of the low stage; and a bypass heat exchanger for effectuating a heat exchange relationship between the first refrigerant in the bypass line and the first refrigerant in the input conduit of the low stage , the bypass line passing through a bypass heat exchanger in heat exchange relationship with the first refrigerant in the low stage input conduit upstream of the stage heat exchanger .