Refrigerating cycle apparatus

Abstract

A refrigerating cycle apparatus includes a circulation refrigerant, a compressor, a condenser, an expansion valve, an evaporator, and an internal heat exchanger. The internal heat exchanger is disposed to perform heat exchange between a high pressure circulation refrigerant flowing from the condenser to the expansion valve and a low pressure circulation refrigerant flowing from the evaporator and the compressor. The circulation refrigerant has a property indicating an isentropic line having a gradient greater than a gradient of an isentropic line of a R134a refrigerant and a saturation characteristic curve having a two-phase region enthalpy width smaller than a two-phase region enthalpy width of the R134a refrigerant, on a p-h chart.

1 . A refrigerating cycle apparatus comprising:
 a circulation refrigerant having a property that indicates an isentropic line and a saturation characteristic line on a p-h chart, the isentropic line having a gradient greater than an isentropic line of a R134a refrigerant, the saturation, characteristic line having a two-phase region enthalpy width smaller than a two-phase region enthalpy width of a saturation characteristic line of the R134a, the two-phase region enthalpy width being defined between a saturated liquid line and a saturated gas line;   a compressor that draws and compresses the circulation refrigerant into a high pressure circulation refrigerant;   a condenser-that condenses the high pressure circulation refrigerant;   an expansion valve that expands the high pressure circulation refrigerant into a low pressure circulation refrigerant;   an evaporator that evaporates the low pressure circulation refrigerant; and   an internal heat exchanger that performs heat exchange between the high pressure circulation refrigerant flowing from the condenser to the expansion valve and the low pressure circulation refrigerant flowing from the evaporator to the compressor.   
   
   
       2 . The refrigerating cycle apparatus according to  claim 1 , wherein
 at a saturated temperature of 0 degree Celsius on the p-h chart, the two-phase region enthalpy width of the circulation refrigerant is at most 85% of the two-phase region enthalpy width of the R134a refrigerant, and   the internal heat exchanger is configured to increase an enthalpy width of one of a condensing process and an evaporating process on the p-h chart by at least 5% of the two-phase region enthalpy width of the circulation refrigerant at the saturated temperature of 0 degree Celsius.   
   
   
       3 . The refrigerating cycle apparatus according to  claim 2 , wherein
 at the saturated temperature of 0 degrees Celsius on the p-h chart, the two-phase region enthalpy width of the circulation refrigerant is at least 75% and at most 85% of the two-phase region enthalpy width of the R134a refrigerant, and   the internal heat exchanger is configured to increase the enthalpy width of the one of the condensing process and the evaporating process on the p-h chart by at least 5% and at most 10% of the two-phase region enthalpy width of the circulation refrigerant at the saturated temperature of 0 degree Celsius.   
   
   
       4 . The refrigerating cycle apparatus according to  claim 1 , wherein
 the isentropic line of the circulation refrigerant passes through the saturated gas line of the circulation refrigerant at a saturated temperature of 0 degrees Celsius on the p-h chart, and   the gradient of the isentropic line of the circulation refrigerant is at least. 0.044 and at most 0.054.   
   
   
       5 . The refrigerating cycle apparatus according to  claim 1 , wherein
 the circulation refrigerant is a mixture refrigerant containing at least one low-GWP refrigerant.   
   
   
       6 . The refrigerating cycle apparatus according to  claim 1 , wherein
 the expansion valve has a normal charge characteristic to control a superheat degree of the circulation refrigerant at an outlet of the evaporator to a target value that is at least 0 degree Celsius and at most 6 degrees Celsius.   
   
   
       7 . The refrigerating cycle apparatus according to  claim 6 , wherein
 the compressor includes an electric motor and a control circuit, and   the control circuit is disposed to receive heat of the circulation refrigerant.   
   
   
       8 . The refrigerating cycle apparatus according to  claim 1 , wherein
 the expansion valve has a cross charge characteristic to control a superheat degree of the circulation refrigerant at an outlet of the evaporator to at least 0 degree Celsius and at most 6 degrees Celsius in a normal operation region.   
   
   
       9 . The refrigerating cycle apparatus according to  claim 8 , wherein
 the normal operation region corresponds to a range where refrigerant pressure at the outlet of the evaporator is at least 0.2 MPaG and at most 0.3 MPaG, and   the cross charge characteristic is set so that the superheat degree at the outlet of the evaporator is controlled to 0 degree Celsius when the refrigerant pressure at the outlet of the evaporator is 0.3 MPaG.   
   
   
       10 . The refrigerating cycle apparatus according to  claim 1 , for being used for a vehicular air conditioning apparatus, wherein
 the internal heat exchanger includes a double tube having an inner tube and an outer tube.