Refrigeration system mounted within a deck

A refrigeration system for use with an ultra-low temperature freezer having a deck and a refrigerated cabinet supported above the deck, comprising:

• a first refrigeration stage defining a first fluid circuit for circulating a first refrigerant, the first refrigeration stage having a first compressor, a condenser, a first filter/dryer, a first expansion device, and a first accumulator in fluid communication with the first fluid circuit;
• a second refrigeration stage defining a second fluid circuit for circulating a second refrigerant, the second refrigeration stage having a second compressor, a second filter/dryer, a second expansion device, an evaporator, and a second accumulator in fluid communication with the second fluid circuit;
• an insulated enclosure supported within the deck;
• and
• a split-flow heat exchanger in fluid communication with the first and second fluid circuits,
• wherein the split-flow heat exchanger, the first expansion device, the first accumulator, and the second filter/dryer are located within the insulated enclosure.

An ultra-low temperature freezer, comprising:

• a deck;
• a refrigerated cabinet supported above the deck;
• and
• a refrigeration system in thermal communication with the refrigerated cabinet, the refrigeration system comprising:
• a first refrigeration stage defining a first fluid circuit for circulating a first refrigerant, the first refrigeration stage having a first compressor, a condenser, and a first expansion device in fluid communication with the first fluid circuit;
• a second refrigeration stage defining a second fluid circuit for circulating a second refrigerant, the second refrigeration stage having a second compressor, a second expansion device, and an evaporator in fluid communication with the second fluid circuit;
• an insulated enclosure supported within the deck;
• and
• a split-flow heat exchanger in fluid communication with the first and second fluid circuits and located within the insulated enclosure.

A method of operating an ultra-low temperature freezer having a deck, a refrigerated cabinet supported above the deck, and an insulated enclosure within the deck, the method comprising:

• circulating a first refrigerant through a first compressor, a condenser, and a first expansion device of a first stage of a refrigeration system;
• circulating a second refrigerant through a second compressor, a second expansion device, and an evaporator of a second stage of the refrigeration system;
• and
• splitting within the insulated enclosure in the deck of the freezer a stream of at least one of the first or second refrigerants into a plurality of streams arranged relative to one or more streams of the other of the first or second refrigerants so as to exchange heat between the first and second refrigerants.