Free cooling cascade arrangement for refrigeration system

摘要

A refrigeration system includes a medium temperature subsystem circulating a coolant in a closed loop between at least one medium temperature chiller and at least one medium temperature load and at least one cascade heat exchanger, and a low temperature subsystem circulating a coolant in a closed loop between at least one low temperature heat exchanger and at least one low temperature load. A cooling circuit is provided for circulating a coolant and includes a first pump and a second pump and a fluid cooler and a valve, and interfaces with the medium temperature chiller and the low temperature chiller. The valve is movable to a closed position to define a first flow path and a second flow path, where the first flow path includes the first pump and the medium temperature chiller and fluid cooler, and the second flow path including the second pump and the low temperature heat exchanger and the cascade heat exchanger.

主权项

1. A refrigeration system, comprising:
a plurality of medium temperature heat exchangers arranged in parallel and configured to cool a medium temperature coolant for circulation in a first closed loop between the medium temperature heat exchangers and a plurality of medium temperature refrigerated display cases; a plurality of low temperature heat exchangers arranged in parallel and configured to cool a low temperature coolant for circulation in a second closed loop between the low temperature heat exchangers and a plurality of low temperature refrigerated display cases; a condenser coolant supply header configured to supply a condenser coolant to the low and medium temperature heat exchangers; a condenser coolant suction header configured to receive the condenser coolant from the low and medium temperature heat exchangers; a fluid cooler configured to cool the condenser coolant in the condenser coolant supply header; a cascade heat exchanger separate from the medium temperature heat exchangers and arranged in parallel with the medium temperature refrigerated display cases along the first closed loop such that the medium temperature heat exchangers provide a supply of the medium temperature coolant to both the cascade heat exchanger and the medium temperature refrigerated display cases in parallel; at least one first pump configured to pump the condenser coolant from the condenser coolant suction header to the coolant supply header and through the fluid cooler; at least one second pump configured to pump the condenser coolant from the coolant suction header to the condenser coolant supply header and through the cascade heat exchanger; a valve disposed on the condenser coolant supply header between the low temperature heat exchangers and the fluid cooler, the valve movable to a closed position to define a first cooling flow path comprising the first pump and the fluid cooler and the medium temperature heat exchangers, and a second cooling flow path comprising the second pump and the cascade heat exchanger and the low temperature heat exchangers; wherein the cascade heat exchanger is configured to receive both the coolant from the low temperature heat exchangers and the supply of the medium temperature coolant from the medium temperature heat exchangers when the valve is closed and to cool the coolant from the low temperature heat exchangers using the supply of the medium temperature coolant from the medium temperature heat exchangers.