Refrigeration cycle apparatus and method of operating the same

Abstract

A refrigeration cycle apparatus includes a compressor and sets a heating-mode lower limit refrigerant volume flow rate through the compressor. The heating-mode lower limit refrigerant volume flow rate is a lower limit of a volume flow rate in a heating operation. The apparatus controls a rotation speed of the compressor such that the volume flow rate in the heating operation is greater than or equal to the heating-mode lower limit refrigerant volume flow rate. The heating-mode lower limit refrigerant volume flow rate includes a first lower limit for use of an R410A refrigerant and a second lower limit for use of an R32 refrigerant. When using the R32 refrigerant in the refrigeration cycle apparatus designed for the R410A refrigerant, the apparatus performs correction such that the lower limit is increased from the first lower limit to the second lower limit to control the rotation speed of the compressor.

1 . A refrigeration cycle apparatus including a variable displacement compressor and pipes designed for R410A refrigerant,
 the apparatus setting a heating-mode lower limit refrigerant volume flow rate in the compressor, the heating-mode lower limit refrigerant volume flow rate being a lower limit of a volume flow rate in a heating operation, the apparatus controlling a frequency of the compressor such that the volume flow rate in the heating operation is greater than or equal to the heating-mode lower limit refrigerant volume flow rate,   the heating-mode lower limit refrigerant volume flow rate including a first lower limit for use of R410A refrigerant and a second lower limit for use of R32 refrigerant in the refrigeration cycle apparatus designed for the R410A refrigerant, the second lower limit being greater than the first lower limit, and   in the heating operation in the use of the R32 refrigerant in the refrigeration cycle apparatus designed for the R410A refrigerant, the apparatus performing correction such that a lower limit is increased from the first lower limit to the second lower limit to control the frequency of the compressor.   
     
     
         2 . The refrigeration cycle apparatus of  claim 1 , wherein the heating-mode lower limit refrigerant volume flow rate is set by determining a lower limit frequency of the compressor. 
     
     
         3 . The refrigeration cycle apparatus of  claim 1 , wherein the heating-mode lower limit refrigerant volume flow rate is set in an upward gas pipe. 
     
     
         4 . The refrigeration cycle apparatus of  claim 1 , wherein the apparatus uses refrigerating machine oil, the refrigerating machine oil in the use of the R32 refrigerant has a density identical to that in the use of the R410A refrigerant, and the second lower limit is higher than the first lower limit by 17% or more. 
     
     
         5 . The refrigeration cycle apparatus of  claim 1 , wherein the apparatus uses a refrigerating machine oil such that a density of a mixture of the R32 refrigerant and a refrigerating machine oil is greater than or equal to 90% and less than or equal to 110% of a density of a mixture of the R410A refrigerant and a refrigerating machine oil, and the second lower limit is higher than the first lower limit by an amount in a range of 11% to 24%. 
     
     
         6 . The refrigeration cycle apparatus of  claim 1 , wherein the apparatus uses ether oil as a refrigerating machine oil in the use of the R410A refrigerant and uses ester oil as a refrigerating machine oil in the use of the R32 refrigerant. 
     
     
         7 . A method of operating a refrigeration cycle apparatus that includes a variable displacement compressor, a condenser, an expansion valve, and an evaporator and that is designed for R410A refrigerant, the method comprising:
 setting a heating-mode lower limit refrigerant volume flow rate in the compressor, the heating-mode lower limit refrigerant volume flow rate being a lower limit of a volume flow rate in a heating operation;   controlling frequency of the compressor such that the volume flow rate in the heating operation is greater than or equal to the heating-mode lower limit refrigerant volume flow rate, the heating-mode lower limit refrigerant volume flow rate including a first lower limit for use of the R410A refrigerant and a second lower limit for use of R32 refrigerant in the refrigeration cycle apparatus designed for the R410A refrigerant, the second lower limit being greater than the first lower limit; and   in the heating operation in the use of the R32 refrigerant in the refrigeration cycle apparatus designed for the R410A refrigerant, performing correction such that a lower limit is increased from the first lower limit to the second lower limit to control the frequency of the compressor.   
     
     
         8 . A refrigeration cycle apparatus including a variable displacement compressor and pipes designed for R410A refrigerant,
 the compressor being configured that frequency is controlled to increase lower limit frequency in a heating operation to be higher than lower limit frequency in a cooling operation, when R32 refrigerant is enclosed into the pipes.