Pulsation attenuation in systems with multiple compression elements

Abstract

In compression systems having multiple sources of pulsation induced noise, provisions are made to reduce the noise by selectively varying the length of adjacent refrigerant lines leading to a common refrigerant manifold. Each of the refrigerant lines is associated with a particular noise source. The feature can be incorporated into compressors operating in parallel or in a single multi-rotor compressor having multiple suction or/and discharge ports. It is equally applicable to both discharge and suction ports.

1 . Apparatus for at least one of reducing pulsation induced noise, reducing vibration level or improving sound quality in an HVAC&R system having a plurality of compressor ports, comprising:
 a plurality of refrigerant lines with each refrigerant line fluidly interconnecting one of said plurality of compressor ports to a common refrigerant manifold;   wherein said plurality of refrigerant lines are of selectively differing lengths so as to result in pressure pulsations cancellation.   
   
   
       2 . Apparatus as set forth in  claim 1  wherein said ports are compressor discharge ports and said refrigerant lines are discharge lines. 
   
   
       3 . Apparatus as set forth in  claim 1  wherein said ports are compressor suction ports and said refrigerant lines are suction lines. 
   
   
       4 . Apparatus as set forth in  claim 1  wherein said plurality of compressor ports comprise two ports and further wherein the difference in lengths of said refrigerant lines is determined by the equation L Dif =n*(c/f), wherein c is the speed of sound of refrigerant, f is the dominant pulsation frequency, and n is an integer number. 
   
   
       5 . Apparatus as set forth in  claim 1  wherein said plurality of ports comprise a plurality of ports within a plurality of compressors connected in parallel. 
   
   
       6 . Apparatus as set forth in  claim 1  wherein said plurality of ports comprises a plurality of ports in a single compressor. 
   
   
       7 . Apparatus as set forth in  claim 6  wherein said single compressor is one of a screw compressor, a scroll compressor, a rotary compressor or a root compressor. 
   
   
       8 . Apparatus as set forth in  claim 1  wherein said HVAC & R system includes at least a compressor, an evaporator and an expansion device. 
   
   
       9 . Apparatus as set forth in  claim 1  wherein the differences in lengths of said refrigerant lines are determined by the equation L Dif =(2/1c)*n*(c/f), wherein c is the speed of sound of refrigerant, f is the dominant pulsation frequency, k is the number of pulsation sources, and n is an integer number. 
   
   
       10 . A method for at least one of reducing pulsation induced noise, reducing vibration level or improving sound quality in an HVAC&R system having a plurality of compressor ports that are susceptible of producing pressure pulsations, comprising the steps of:
 providing a plurality of refrigerant lines with each refrigerant line fluidly interconnecting one of said ports to a common refrigerant manifold;   wherein said plurality of refrigerant lines are of selectively different lengths so as to result in their respective pressure pulsations canceling each other out at the point of their reaching said common refrigerant manifold.   
   
   
       11 . A method as set forth in  claim 10  wherein said ports are compressor discharge ports and said refrigerant lines are discharge lines. 
   
   
       12 . A method as set forth in  claim 10  wherein said ports are compressor suction ports and said refrigerant lines are suction lines. 
   
   
       13 . A method as set forth in  claim 10  wherein said plurality of compressor ports comprise two ports and further wherein the difference in length of said refrigerant lines is determined by the equation L Dif =n*(c/f), wherein c is the speed of sound of refrigerant, f is the dominant pulsation frequency, and n is an integer number. 
   
   
       14 . A method as set forth in  claim 10  wherein said plurality of ports comprise a plurality of ports within a plurality of compressors connected in parallel. 
   
   
       15 . A method as set forth in  claim 10  wherein said plurality of ports comprises a plurality of ports in a single compressor 
   
   
       16 . A method as set forth in  claim 10  wherein the differences in lengths of said refrigerant lines are determined by the equation L Dif =(2/k)*n*(c/f), wherein c is the speed of sound of refrigerant, f is the dominant pulsation frequency, k is the number of pulsation sources, and n is an integer number.