Vapor compression systems using an accumulator to prevent over-pressurization

Abstract

An accumulator acts as a buffer to prevent over-pressurization of the vapor compression system while inactive. By determining the maximum storage temperature and the maximum storage pressure a system will be subject to when inactive, a density of the refrigerant for the overall system can be calculated. Dividing the density by the mass of the refrigerant determines an optimal overall system volume. The volume of the components is subtracted from the overall system volume to calculate the optimal accumulator volume. The optimal accumulator volume is used to size the accumulator so that the accumulator has enough volume to prevent over-pressurization of the system when inactive.

1 . A method of sizing an accumulator for a vapor compression system comprising the steps of: 
 determining a maximum storage temperature of a refrigerant of the system;    determining a maximum storage pressure of the refrigerant of the system; and    utilizing the maximum storage temperature and the maximum storage pressure to determine an optimal accumulator volume of an accumulator.    
   
   
       2 . The method as recited in  claim 1 , further including the steps of adding the accumulator having the optimal accumulator volume, calculating a desired system volume using the maximum storage temperature and the maximum storage pressure, calculating a component volume of the system before the step of adding the accumulator, and calculating the optimal accumulator volume by subtracting the component volume from the desired system volume.  
   
   
       3 . The method as recited in  claim 2 , wherein the step of calculating the optimal accumulator volume includes selecting a volume within 80 to 120 percent of the optimal accumulator volume.  
   
   
       4 . The method as recited in  claim 2 , wherein the step of calculating the optimal accumulator volume includes determining a density of the refrigerant at the maximum storage temperature and the maximum storage pressure and dividing a mass of the refrigerant by the density of the refrigerant.  
   
   
       5 . The method as recited in  claim 2 , wherein the step of calculating the component volume includes adding a total compressor volume of at least one compressor, a total heat rejecting heat exchanger volume of at least one heat rejecting heat exchanger, a total expansion device volume of at least one expansion device, a total heat accepting heat exchanger volume of at least one heat accepting heat exchanger, and a total refrigerant line volume of refrigerant lines.  
   
   
       6 . The method as recited in  claim 5  wherein the step of calculating the component volume further includes adding a total internal heat exchanger volume of at least one internal heat exchanger, adding a total oil separator volume of at least one oil separator, and adding a total filter dryer volume of at least one filter dryer.  
   
   
       7 . The method as recited in  claim 6  wherein the step of calculating the component volume further includes adding a total additional components volume of any additional components.  
   
   
       8 . The method of  claim 1  wherein the step of determining the maximum storage temperature further includes determining a maximum temperature the refrigerant will reach when the system is inactive  
   
   
       9 . The method of  claim 8  wherein the step of determining the maximum storage temperature further includes selecting a temperature between −50 and 200 degrees F.  
   
   
       10 . The method of  claim 1  wherein the step of determining the maximum storage pressure further includes determining a maximum pressure the refrigerant will reach when the system is inactive  
   
   
       11 . The method of  claim 10  wherein the step of determining the maximum storage pressure further includes selecting a pressure between 1000 and 2500 psi.  
   
   
       12 . A method of sizing an accumulator for a vapor compression system comprising the steps of: 
 a) determining a maximum storage temperature of a refrigerant of the system, wherein the maximum storage temperature is a maximum temperature the refrigerant will reach when the system is inactive;    b) determining a maximum storage pressure of the refrigerant of the system, wherein the maximum storage pressure is a maximum pressure the refrigerant will reach when the system is inactive;    c) utilizing the maximum storage temperature and the maximum storage pressure to determine an optimal accumulator volume of the accumulator; and    d) creating the accumulator having the optimal accumulator volume.    
   
   
       13 . The method as recited in  claim 12 , further including the steps of calculating a desired system volume using the maximum storage temperature and the maximum storage pressure, calculating a component volume of the system, and calculating the optimal accumulator volume by subtracting the component volume from the desired system volume.  
   
   
       14 . The method as recited in  claim 13 , wherein the step of calculating the optimal accumulator volume includes selecting a volume within 80 to 120 percent of the optimal accumulator volume.  
   
   
       15 . The method as recited in  claim 13 , wherein the step of calculating the optimal accumulator volume includes determining a density of the refrigerant at the maximum storage temperature and the maximum storage pressure and dividing a mass of the refrigerant by the density of the refrigerant.  
   
   
       16 . The method as recited in  claim 15 , wherein the step of calculating the component volume includes adding a total compressor volume of at least one compressor, a total heat rejecting heat exchanger volume of at least one heat rejecting heat exchanger, a total expansion device volume of at least one expansion device, a total heat accepting heat exchanger volume of at least one heat accepting heat exchanger, and a total refrigerant line volume of refrigerant lines.  
   
   
       17 . The method as recited in  claim 16  wherein the step of calculating the component volume further includes adding a total internal heat exchanger volume of at least one internal heat exchanger, adding a total oil separator volume of at least one oil separator, and adding a total filter dryer volume of at least one filter dryer.  
   
   
       18 . The method as recited in  claim 17  wherein the step of calculating the component volume further includes adding a total additional components volume of any additional components.  
   
   
       19 . The method of  claim 12  wherein the step of determining the maximum storage temperature further includes selecting a temperature between −50 and 200 degrees F.  
   
   
       20 . The method as recited in  claim 12 , wherein the step of determining the maximum storage pressure further includes selecting a pressure between 1000 and 2500 psi.