Patent ID: 8020407

Claim:
A refrigeration system for a vehicle defining a cargo space, the refrigeration system comprising: a first refrigeration circuit for circulating a refrigerant, the first refrigeration circuit including a first heat exchanger; and a second refrigeration circuit for circulating a cryogenic refrigerant, the second refrigeration circuit including a compressor for compressing the cryogenic refrigerant, the first heat exchanger fluidly connected to the compressor to receive the cryogenic refrigerant from the compressor, the first heat exchanger cooling and condensing the cryogenic refrigerant, a second heat exchanger in fluid communication with the first heat exchanger to receive the cryogenic refrigerant from the first heat exchanger and configured to absorb heat from air being directed into the cargo space to cool the cargo space when the second refrigeration circuit operates as a closed loop system in a first mode of operation operable to provide a first cooling capacity of the second refrigeration circuit, and a booster cooling line in fluid communication with the second refrigeration circuit, wherein the booster cooling line includes a valve configured to vent a portion of the cryogenic refrigerant to the atmosphere to absorb additional heat from air being directed into the load space to further cool the load space when the second refrigeration circuit operates as a combined closed loop and open loop system in a second mode of operation operable to provide a second cooling capacity of the second refrigeration circuit greater than the first cooling capacity.