Integrated Cascading Plant

Abstract

An integrated refrigeration and air conditioning plant working with environmentally friendly natural refrigerant carbon dioxide (CO2) and an ozone friendly non CO2 refrigerant. The low temperature refrigeration is provided by evaporating CO2 and the fluid is used as a secondary refrigerant, predominantly in liquid mode, for medium temperature refrigeration. The heat rejection from CO2 occurs to another upper stage cascaded refrigeration system that operates with a ozone friendly non CO2 refrigerant. Since air conditioning applications require cooling at temperatures higher than refrigeration for food sector, cooling for this range is derived from the non CO2 refrigerant.

1 . A climate system for an enclosure, the enclosure having at least one sub-enclosure, the system comprising:
 (a) a refrigeration plant for maintaining a first sub-enclosure within at least one predetermined temperature range including,
 (i) a CO2 circuit for cooling the at least one sub-enclosure; and 
 (ii) a non CO2 refrigerant circuit in heat exchange relationship with the CO2 circuit; 
 and 
   (b) an air conditioning plant for maintaining the enclosure, external of any sub enclosure, within at least one predetermined temperature range including at least one non refrigerant fluid circuit in heat exchange with (i) the non CO2 refrigerant circuit and (ii) an air circulation circuit for the enclosure.   
     
     
         2 . The system of  claim 1  wherein between the CO2 circuit and the non CO2 refrigerant circuit a cascading temperature of −7° C. or higher is maintained. 
     
     
         3 . The system of  claim 1 , wherein the sub-enclosure(s) are medium temperature and/or low temperature sub-enclosures. 
     
     
         4 . The system of  claim 1 , comprising a first and a second non refrigerant fluid circuit, the first circuit for circulating chilled fluid for heat exchange with the air circulation circuit to cool air and the second circuit for circulating warm fluid for heat exchange with the air circulation circuit to warm air. 
     
     
         5 . The system of  claim 1  further comprising a control system for optimising the operation of the system. 
     
     
         6 . The system  claim 4  wherein the control system includes one or more sensors to sense perturbations in the operation of the system and one or more transmitters to generate signals to the CO2 circuit and the non CO2 refrigerant circuit in response to sensing said perturbations.