Patent ID: 11965688
Assignee: THEMRO KING LLC
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F  B | IPC F

Claim 12:
13. A method of operating a transport refrigeration unit comprising:
operating an outer refrigeration cycle to transfer heat from an enclosed cargo space exteriorly of the enclosed cargo space, to maintain a target temperature associated with the cargo space, the outer refrigeration cycle extending through a condenser positioned for rejecting heat to external air and an evaporator positioned for transferring heat from a controlled environment within the enclosed cargo space;
operating a first stage cycle of a cascade refrigeration cycle to reject heat exteriorly of the cargo space, the first stage cycle extending through the condenser positioned for rejecting heat to external air such that said condenser is in common between the outer refrigeration cycle and the first stage cycle;
operating an inner refrigeration cycle to transfer heat from an interior of a container installed within the cargo space, the inner refrigeration cycle extending through a condenser positioned for rejecting heat from the inner refrigeration cycle and an evaporator positioned for transferring heat from the interior of the container, the inner refrigeration cycle forming a second stage cycle of the cascade refrigeration cycle, with an inter-stage heat exchanger being provided between the first stage cycle and the second stage cycle;
wherein the inner refrigeration cycle is operated to maintain thermodynamic conditions including:
a target interior temperature of the container of −70° C. or less.