Refrigeration systems and methods

Abstract

Disclosed are distributed refrigeration systems, comprising: a plurality of first refrigeration circuits, with each first refrigeration circuit being provided in a respective refrigeration unit; a second refrigeration circuit, the second refrigeration circuit comprising a second circuit heat exchanger; and a third refrigeration circuit, wherein each first circuit heat exchanger is arranged to transfer heat energy between its respective first refrigeration circuit and the second refrigeration circuit; and a third circuit heat exchanger arranged to transfer heat energy between the second refrigeration circuit and the third refrigeration circuit.

1 . A refrigeration system for providing cooling at at least a low temperature cooling level and a medium temperature cooling level, said system comprising:
 (a) a low temperature refrigeration unit comprising a low temperature refrigeration circuit, said low temperature refrigeration circuit comprising:
 (i) a low temperature refrigerant consisting essentially of HFO-1234yf; 
 (ii) a compressor for compressing said low temperature refrigerant; 
 (iii) a low temperature evaporator for absorbing heat from a space in the low temperature refrigeration unit by evaporating said low temperature refrigerant, and 
 (iv) a low temperature heat exchanger for rejecting heat from said low temperature refrigerant; 
   (b) a medium temperature refrigeration unit comprising a medium temperature refrigeration circuit, said medium temperature refrigeration circuit comprising:
 (i) medium temperature refrigerant consisting essentially of HFO-1234yf circulating in said system; 
 (ii) a compressor for compressing said medium temperature refrigerant; 
 (iii) a medium temperature evaporator for absorbing heat from a space in the medium temperature refrigeration unit by evaporating said medium temperature refrigerant; and 
 (iv) a medium temperature heat exchanger for rejecting heat from said medium temperature refrigerant; and 
   (c) a third refrigeration circuit arranged to accept heat rejected from each of said low temperature heat exchanger and medium temperature heat exchanger at a temperature of from about 40 F to about 80 F and wherein the refrigerant in said third refrigeration circuit consists essentially of transHFO-1233zd.   
     
     
         2 . The refrigeration system of  claim 1 , wherein at least one of said low temperature heat exchanger and said medium temperature heat exchanger is a flooded heat exchanger and wherein said third refrigeration circuit comprises a pump for circulating said third refrigerant. 
     
     
         3 . The refrigeration system of  claim 2 , wherein said third refrigeration circuit does not include a compressor. 
     
     
         4 . The refrigeration system of  claim 2 , wherein said third refrigeration circuit includes a compressor and a fluid receiver. 
     
     
         5 . The refrigeration system of  claim 1 , wherein each of the low temperature and medium temperature refrigeration units comprises a space to be chilled. 
     
     
         6 . The refrigeration system of  claim 1 , wherein each of the low temperature and medium temperature refrigeration units is located within a first area. 
     
     
         7 . The refrigeration system of  claim 1 , wherein each of said low temperature refrigerant and said medium temperature refrigerants is flammable and wherein said third refrigerant is non-flammable. 
     
     
         8 . The refrigeration system of  claim 7 , wherein the third refrigeration circuit is arranged to release said third refrigerant in or in the vicinity of said low temperature or said medium temperature refrigerant unit in the event of a leak of said low temperature or said medium temperature refrigerant. 
     
     
         9 . A refrigeration system for providing cooling at at least a low temperature and a medium temperature cooling level, said system comprising:
 (a) a low temperature refrigeration unit comprising a low temperature refrigeration circuit, said low temperature refrigeration circuit comprising:
 (i) low temperature refrigerant circulating in said system; 
 (ii) a compressor for compressing said low temperature refrigerant; 
 (iii) a low temperature evaporator for absorbing heat from a space in the low temperature refrigeration unit by evaporating said low temperature refrigerant, and 
 (iv) a low temperature heat exchanger for rejecting heat from said low temperature refrigerant; 
   (b) a medium temperature refrigeration unit comprising a medium temperature refrigeration circuit, said medium temperature refrigeration circuit comprising:
 (i) medium temperature refrigerant circulating in said system; 
 (ii) a compressor for compressing said medium temperature refrigerant; 
 (iii) a medium temperature evaporator for absorbing heat from a space in the medium temperature refrigeration unit by evaporating said medium temperature refrigerant; and 
 (iv) a medium temperature heat exchanger for rejecting heat from said medium temperature refrigerant; and 
   (c) a third refrigeration circuit comprising:
 (i) a third refrigerant consisting essentially of transHFO-1233zd; 
 (ii) a compressor for compressing said third refrigerant; 
 (iii) a flooded evaporator arranged to accept heat rejected from each of said low temperature refrigerant and said medium temperature refrigerant in said low and medium temperature heat exchangers by evaporating said common refrigerant at a temperature of from about 50° F. to about 70° F. 
   
     
     
         10 . The refrigeration system of  claim 1 , wherein each of said low temperature and medium temperature refrigerants is selected from the group consisting of R744, one or more C2-C4 hydrocarbons, R1234yf, and combinations of these. 
     
     
         11 . The refrigeration system of  claim 10 , wherein at least one of the low temperature and medium temperature refrigerants comprises at least one hydrocarbon. 
     
     
         12 . The refrigeration system of  claim 11 , wherein said at least one hydrocarbon comprises R290. 
     
     
         13 . The refrigeration system of  claim 10 , wherein said wherein at least one of the low temperature and medium temperature refrigerants comprises HFO-1234yf. 
     
     
         14 . The refrigeration system of  claim 9 , wherein the common refrigeration circuit comprises at least a first branch that when in operation rejects heat by heat exchange with ambient air and a compressor branch that when in operation rejects heat to a compression refrigeration system. 
     
     
         15 . The refrigeration system of  claim 14 , wherein refrigerant entering the ambient cooling branch is cooled by ambient air. 
     
     
         16 . The refrigeration system of  claim 9  wherein said compressor in said low temperature refrigeration unit has a power rating of less than about 1 horsepower. 
     
     
         17 . The refrigeration system of  claim 9  wherein said compressor in said medium temperature refrigeration unit has a power rating of less than about 1 horsepower. 
     
     
         18 . The refrigeration system of  claim 9  wherein said compressor in said medium temperature refrigeration unit has a power rating of less than about 1 horsepower and wherein said compressor in said medium temperature refrigeration unit has a power rating of less than about 1 horsepower. 
     
     
         19 . The refrigeration system of  18  wherein said third refrigeration system is located substantially completely outside of said low temperature refrigeration unit and substantially completely outside of said medium temperature refrigeration unit. 
     
     
         20 . The refrigeration system of  9  wherein said third refrigeration system is located substantially completely outside of said low temperature refrigeration unit and substantially completely outside of said medium temperature refrigeration unit.