Modular co2 refrigeration system

A cascade CO2 refrigeration system, comprising:

• a medium temperature loop for circulating a medium temperature refrigerant, the medium temperature loop including a heat exchanger having a first side and a second side, the first side configured to evaporate the medium temperature refrigerant and a medium temperature compressor, a medium temperature expansion device, a condenser, and a medium temperature expansion device packaged in a modular unit with the heat exchanger;
• a low temperature loop for circulating a CO2 refrigerant, the loop including:
• a low temperature discharge header configured to circulate the CO2 refrigerant through the second side of the heat exchanger, the second side of the heat exchanger configured to condense the CO2 refrigerant;
• a liquid-vapor separator configured to collect liquid CO2 refrigerant and to direct vapor CO2 refrigerant to the second side of the heat exchanger;
• a pump;
• a liquid CO2 refrigerant supply header;
• a plurality of medium temperature loads configured to receive liquid CO2 refrigerant from the liquid CO2 refrigerant supply header for use as a liquid coolant in the medium temperature loads;
• a plurality of low temperature loads;
• a low temperature expansion device associated with the low temperature loads and configured to expand the liquid CO2 refrigerant from the liquid CO2 refrigerant supply header into vapor CO2 refrigerant for use as a vapor refrigerant by the low temperature loads.

A cascade refrigeration system having a common subcooled liquid supply for both low temperature refrigerated cases and medium temperature refrigerated cases, the system comprising:

• an upper cascade portion for circulating a first refrigerant, the upper cascade portion including an upper cascade compressor, an upper cascade condenser, an upper cascade expansion device, and a heat exchanger having a first side and a second side, the first side configured to evaporate the first refrigerant;
• a lower cascade portion for circulating a second refrigerant, the lower cascade portion including a lower cascade compressor configured to direct the second refrigerant to the second side of the heat exchanger, the second side of the heat exchanger 11 configured to condense the second refrigerant, a liquid-vapor separator configured to direct liquid second refrigerant to the common subcooled liquid supply and to direct vapor second refrigerant to the second side of the heat exchanger;
• a plurality of medium temperature refrigerated cases configured to receive liquid second refrigerant from the common subcooled liquid supply for use as a coolant in the medium temperature refrigerated cases, and
• an expansion device associated with a plurality of the low temperature refrigerated cases and configured to expand the liquid second refrigerant from the common subcooled liquid supply for use in the low temperature refrigerated cases.

A cascade refrigeration system having a common liquid supply for both low temperature refrigeration loads and medium temperature refrigeration loads, the system comprising:

• an upper cascade portion for circulating a first refrigerant, the upper cascade portion including an upper cascade compressor, an upper cascade condenser, an upper cascade expansion device, and a heat exchanger having a first side and a second side, the first side configured to evaporate the first refrigerant;
• a lower cascade portion for circulating a second refrigerant, the lower cascade portion including a lower cascade compressor configured to direct the second refrigerant to the second side of the heat exchanger, the second side of the heat exchanger configured to condense the second refrigerant;
• a liquid-vapor separator configured to receive the liquid second refrigerant from the second side of the heat exchanger and to provide a source of liquid second refrigerant for the common liquid supply;
• a plurality of medium temperature refrigeration loads configured to receive liquid second refrigerant from the common liquid supply for use as a coolant in the medium temperature refrigeration loads, and
• an expansion device associated with a plurality of the low temperature refrigeration loads and configured to expand the liquid second refrigerant from the common liquid supply into a liquid-vapor mixture for use in the low temperature refrigeration loads.

A cascade refrigeration system having a common liquid supply for both low temperature refrigeration loads and medium temperature refrigeration loads, the system comprising:

• an upper cascade portion for circulating a first refrigerant, the upper cascade portion including an upper cascade compressor, an upper cascade condenser, an upper cascade expansion device, and a heat exchanger having a first side and a second side, the first side configured to evaporate the first refrigerant;
• a lower cascade portion for circulating a CO2 refrigerant, the lower cascade portion including a lower cascade compressor configured to direct the second refrigerant to the second side of the heat exchanger, the second side of the heat exchanger configured to condense the second refrigerant;
• a de-superheating heat exchanger disposed between the lower cascade compressor and the heat exchanger and configured to pre-cool the CO2 refrigerant before entering the heat exchanger;
• a liquid-vapor separator configured to receive the liquid CO2 refrigerant from the second side of the heat exchanger and to provide a source of liquid CO2 refrigerant for the common liquid supply;
• a plurality of medium temperature refrigeration loads configured to receive liquid CO2 refrigerant from the common liquid supply for use as a coolant in the medium temperature refrigeration loads, and
• at least one expansion device associated with a plurality of the low temperature refrigeration loads and configured to expand the liquid CO2 refrigerant from the common liquid supply for use in the low temperature refrigeration loads.

A cascade refrigeration system having a liquid supply for both low temperature refrigeration loads and medium temperature refrigeration loads, the system comprising:

• an upper cascade portion for circulating a first refrigerant, the upper cascade portion including an upper cascade compressor, an upper cascade condenser, an upper cascade expansion device, and a heat exchanger having a first side and a second side, the first side configured to evaporate the first refrigerant;
• a lower cascade portion for circulating a CO2 refrigerant, the lower cascade portion including a lower cascade compressor configured to direct the second refrigerant to the second side of the heat exchanger, the second side of the heat exchanger configured to condense the second refrigerant;
• a receiver configured to receive the liquid CO2 refrigerant from the second side of the heat exchanger and to provide a source of liquid CO2 refrigerant for the liquid supply;
• at least one expansion device associated with a plurality of the low temperature refrigeration loads and configured to expand the liquid CO2 refrigerant from the liquid supply for use in the low temperature refrigeration loads;
• at least one valve disposed on a piping section between the low temperature refrigeration loads and the lower cascade compressor;
• and
• at least one check valve disposed between the piping section and the common liquid supply.

A CO2 refrigeration system, comprising:

• an upper cascade portion for circulating a first refrigerant, the upper cascade portion including an upper cascade compressor, an upper cascade condenser, an upper cascade expansion device, and a first heat exchanger having a first side and a second side, the first side configured to evaporate the first refrigerant;
• a lower cascade portion for circulating a CO2 refrigerant, the lower cascade portion including a lower cascade compressor configured to direct the second refrigerant to the second side of the first heat exchanger, the second side of the first heat exchanger configured to condense the second refrigerant;
• a second heat exchanger disposed in an external environment for cooling by ambient air temperature, the second heat exchanger located between the lower cascade compressor and the first heat exchanger and configured to condense the CO2 refrigerant into a liquid CO2 refrigerant when the ambient air temperature is below a predetermined level;
• a receiver configured to receive the liquid CO2 refrigerant from the second side of the first heat exchanger when the ambient temperature is above the predetermined temperature, and to receive the liquid CO2 refrigerant from the second heat exchanger when the ambient air temperature is below the predetermined temperature;
• and
• a plurality of refrigeration loads configured to receive the liquid CO2 refrigerant from the receiver for use as a coolant.