Tandem compressor of different types

Abstract

A refrigerant system having tandem compressors includes at least two compressors of different types. By utilizing the two distinct compressor types, a greater difference in the provided capacity of the two compressors can be achieved at part-load conditions, as well as a particular compressor type can be engaged at specific environmental conditions to provide the most efficient operation of the refrigerant system.

1 . A refrigerant system comprising:
 a tandem compressor unit including at least two compressors receiving refrigerant from the refrigerant system, compressing the refrigerant and delivering the refrigerant into the refrigerant system;   a heat rejection heat exchanger positioned downstream of said tandem compressor unit, an expansion device positioned downstream of said heat rejection heat exchanger, and an evaporator positioned downstream of said expansion device, refrigerant passing from said tandem compressor unit to said heat rejection heat exchanger, through said expansion device to said evaporator, and back to said tandem compressor unit; and   said at least two compressors of said tandem compressor unit being of distinct types.   
     
     
         2 . The refrigerant system as set forth in  claim 1 , wherein said at least two compressors of said tandem compressor unit have a common suction manifold and a common discharge manifold. 
     
     
         3 . The refrigerant system as set forth in  claim 1 , wherein said at least two compressors of said tandem compressor unit have at least one of a common suction manifold and a common discharge manifold. 
     
     
         4 . The refrigerant system as set forth in  claim 1 , wherein said at least two compressors of said tandem compressor unit are of different sizes. 
     
     
         5 . The refrigerant system as set forth in  claim 1 , wherein an economizer cycle is incorporated into the refrigerant system. 
     
     
         6 . The refrigerant system as set forth in  claim 5 , wherein said economizer cycle returns a tapped refrigerant to an intermediate compression point in at least one of said at least two compressors of said tandem compressor unit. 
     
     
         7 . The refrigerant system as set forth in  claim 6 , wherein said economizer circuit returns refrigerant to an intermediate compression point only in some of said at least two compressors of said tandem compressor unit. 
     
     
         8 . The refrigerant system as set forth in  claim 7 , wherein said some of said at least two compressors have a common intermediate pressure manifold. 
     
     
         9 . The refrigerant system as set forth in  claim 5 , wherein said at least two compressors of said tandem compressor unit have a common suction manifold and a common discharge manifold. 
     
     
         10 . The refrigerant system as set forth in  claim 5 , wherein said at least two compressors of said tandem compressor unit have at least one of a common suction manifold and a common discharge manifold. 
     
     
         11 . The refrigerant system as set forth in  claim 5 , wherein said at least two tandem compressors of said tandem compressor unit are of different sizes. 
     
     
         12 . The refrigerant system as set forth in  claim 1 , wherein a bypass function is included into the refrigerant system. 
     
     
         13 . The refrigerant system as set forth in  claim 1 , wherein at least one of said two compressors of said tandem compressor unit is a scroll compressor. 
     
     
         14 . The refrigerant system as set forth in  claim 1 , wherein at least one of said at least two compressors of said tandem compressor unit is a screw compressor. 
     
     
         15 . The refrigerant system as set forth in  claim 1 , wherein at least one of said at least two compressors of said tandem compressor unit is a rotary compressor. 
     
     
         16 . The refrigerant system as set forth in  claim 1 , wherein at least one of said at least two compressors of said tandem compressor unit is a reciprocating compressor. 
     
     
         17 . The refrigerant system as set forth in  claim 1 , wherein said at least two compressors of distinct types being utilized for selective unloading of the refrigerant system. 
     
     
         18 . The refrigerant system as set forth in  claim 1 , wherein said at least two compressors of distinct types being utilized for the refrigerant system efficiency boost by selectively engaging a certain compressor at certain environmental conditions. 
     
     
         19 . The refrigerant system as set forth in  claim 1 , wherein a tap selectively taps refrigerant upstream of said expansion device, expands that tapped refrigerant to an intermediate pressure, and returns it to an intermediate compression point in at least one of said at least two compressors of said tandem compressor unit. 
     
     
         20 . A method of operating a refrigerant system comprising the steps of:
 providing a tandem compressor unit that includes at least two compressors receiving refrigerant from the refrigerant system, compressing the refrigerant and delivering the refrigerant into the refrigerant system;   positioning a heat rejection heat exchanger downstream of said tandem compressor unit, positioning an expansion device downstream of said heat rejection heat exchanger, and positioning an evaporator downstream of said expansion device, refrigerant passing from said tandem compressor unit to said heat rejection heat exchanger, through said expansion device to said evaporator, and back to said tandem compressor unit; and   said at least two compressors of said tandem compressor unit being of distinct types.   
     
     
         21 . The method as set forth in  claim 20 , wherein said at least two compressors of distinct types being utilized for selective unloading of the refrigerant system. 
     
     
         22 . The method as set forth in  claim 20 , wherein said at least two compressors of distinct types being utilized for the refrigerant system efficiency boost by selectively engaging a certain compressor at certain environmental conditions.