Free cooling cascade arrangement for refrigeration system

A refrigeration system, comprising:

• at least one medium temperature chiller having a first heat exchanger and a second heat exchanger, the first heat exchanger for cooling a medium temperature coolant circulated to at least one medium temperature refrigerated display case;
• at least one low temperature chiller having a first heat exchanger and a second heat exchanger, the first heat exchanger for cooling a low temperature coolant circulated to at least one low temperature refrigerated display case;
• a condenser coolant supply header configured to supply a condenser coolant to the second heat exchanger in the low and medium temperature chillers;
• a condenser coolant suction header configured to receive the condenser coolant from the second heat exchanger in the low and medium temperature compact chiller units;
• a fluid cooler configured to receive and cool the condenser coolant;
• a cascade heat exchanger configured to receive a supply of the medium temperature coolant from the medium temperature chillers;
• at least one condenser coolant pump configured to pump the condenser coolant from the condenser coolant suction header to the condenser coolant supply header and through the fluid cooler;
• at least one cascade pump configured to pump the condenser coolant from the condenser coolant suction header to the condenser coolant supply header and through the cascade heat exchanger;
• and
• a valve movable to a closed position to define a first cooling flow path comprising the condenser pump and the fluid cooler and the medium temperature chillers, and a second cooling flow path comprising the cascade pump and the cascade heat exchanger and the low temperature chillers.

A refrigeration system, comprising:

• 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;
• a low temperature subsystem circulating a coolant in a closed loop between at least one low temperature chiller and at least one low temperature load;
• a cooling circuit for circulating a coolant, the cooling circuit having a first pump and a second pump and a fluid cooler and a valve, and interfacing with the medium temperature chiller and the low temperature chiller;
• wherein the valve is movable to a closed position defining a first flow path and a second flow path, the first flow path including the first pump and the medium temperature chiller and fluid cooler and the second flow path including the second pump and the low temperature chiller and the cascade heat exchanger.