Refrigeration apparatus

Abstract

The present disclosure allows for easy settling of control of capability of an refrigeration apparatus for performing a supercritical refrigeration cycle. An air conditioner ( 10 ) includes: a refrigerant circuit ( 20 ) sequentially connecting a compressor ( 21 ), an outdoor heat exchanger ( 23 ), an outdoor expansion valve ( 24 ), and an indoor heat exchanger ( 27 ), and performing a supercritical refrigeration cycle in which a high pressure is a supercritical pressure or higher; and a controller ( 40 ) for controlling a plurality of objects of control including at least the compressor ( 21 ) and the outdoor expansion valve ( 24 ). The controller ( 40 ) concurrently controls the plurality of objects of control, thereby concurrently controlling a predetermined physical value as an index of an ability of the refrigeration apparatus, and the high pressure of the refrigeration cycle.

1 . A refrigeration apparatus comprising:
 a refrigerant circuit ( 20 ) sequentially connecting a compression mechanism ( 21 ), a heat source side heat exchanger ( 23 ), an expansion mechanism ( 24 ), and a utilization side heat exchanger ( 27 ), and performing a supercritical refrigeration cycle in which a high pressure is a supercritical pressure of a refrigerant or higher; and   a control section ( 40 ) for controlling a plurality of objects of control including at least the compression mechanism ( 21 ) and the expansion mechanism ( 24 ), wherein   the control section ( 40 ) concurrently controls the plurality of objects of control, thereby concurrently controlling a predetermined physical value as an index of a capability of the refrigeration apparatus, and the high pressure of the refrigeration cycle.   
   
   
       2 . The refrigeration apparatus of  claim 1 , wherein
 the control section ( 40 ) receives the predetermined physical value, and the high pressure of the refrigeration cycle as inputs, generates control signals each corresponding to the plurality of objects of control by associating the physical value and the high pressure with each other, and outputs the control signals to the corresponding objects of control, respectively, thereby concurrently controlling the predetermined physical value, and the high pressure of the refrigeration cycle.   
   
   
       3 . The refrigeration apparatus of  claim 1 , further comprising:
 a heat source side fan ( 28 ) for feeding air to the heat source side heat exchanger ( 23 ) in which the refrigerant exchanges heat with the air, wherein in cooling operation,   the predetermined physical value includes, an evaporating temperature of the refrigerant in the utilization side heat exchanger ( 27 ), and a degree of superheat of the refrigerant at an outlet of the utilization side heat exchanger ( 27 ),   the objects of control further include the heat source side fan ( 28 ), and   the control section ( 40 ) receives the evaporating temperature of the refrigerant, the degree of superheat of the refrigerant, and the high pressure of the refrigeration cycle as inputs, and concurrently controls the compression mechanism ( 21 ), the expansion mechanism ( 24 ), and the heat source side fan ( 28 ), thereby concurrently controlling the evaporating temperature of the refrigerant, the degree of superheat of the refrigerant, and the high pressure of the refrigeration cycle.   
   
   
       4 . The refrigeration apparatus of  claim 1 , wherein in heating operation,
 the predetermined physical value includes a degree of superheat of the refrigerant at an outlet of the heat source side heat exchanger ( 23 ), and   the control section ( 40 ) receives the degree of superheat of the refrigerant, and the high pressure of the refrigeration cycle as inputs, and concurrently controls the compression mechanism ( 21 ) and the expansion mechanism ( 24 ), thereby concurrently controlling the degree of superheat of the refrigerant, and the high pressure of the refrigeration cycle.   
   
   
       5 . The refrigeration apparatus of  claim 1 , wherein
 the compression mechanism includes a first compressor ( 21   a ) for sucking and compressing a low pressure refrigerant, and a second compressor ( 21   b ) for further compressing and discharging the refrigerant discharged from the first compressor ( 21   a ),   the expansion mechanism includes a first expansion mechanism ( 24 ) for expanding a high pressure refrigerant, and a second expansion mechanism ( 26 ) for further expanding the refrigerant expanded to an intermediate pressure refrigerant in the first expansion mechanism ( 24 ),   in cooling operation,
 the predetermined physical value includes an evaporating temperature of the refrigerant in the utilization side heat exchanger ( 27 ), a degree of superheat of the refrigerant at an outlet of the utilization side heat exchanger ( 27 ), and an intermediate pressure of the refrigeration cycle, and 
 the control section ( 240 ) receives the evaporating temperature of the refrigerant, the degree of superheat of the refrigerant, the intermediate pressure of the refrigeration cycle, and the high pressure of the refrigeration cycle as inputs, and concurrently controls the first and second compressors ( 21   a,    21   b ), and the first and second expansion mechanisms ( 24 ,  26 ), thereby concurrently controlling the evaporating temperature of the refrigerant, the degree of superheat of the refrigerant, the intermediate pressure of the refrigeration cycle, and the high pressure of the refrigeration cycle. 
   
   
   
       6 . The refrigeration apparatus of  claim 1 , wherein
 the compression mechanism includes a first compressor ( 21   a ) for sucking and compressing a low pressure refrigerant, and a second compressor ( 21   b ) for further compressing and discharging the refrigerant discharged from the first compressor ( 21   a ),   the expansion mechanism includes a first expansion mechanism ( 24 ) for expanding a high pressure refrigerant, and a second expansion mechanism ( 26 ) for further expanding the refrigerant expanded to an intermediate pressure refrigerant in the first expansion mechanism ( 24 ),   in heating operation,
 the predetermined physical value includes, an evaporating temperature of the refrigerant in the heat source side heat exchanger ( 23 ), a degree of superheat of the refrigerant at an outlet of the heat source side heat exchanger ( 23 ), and a gas cooler outlet temperature which is a temperature of the refrigerant at an outlet of the utilization side heat exchanger ( 27 ), and 
 the control section ( 240 ) receives the evaporating temperature of the refrigerant, the degree of superheat of the refrigerant, the gas cooler outlet temperature of the refrigerant, and the high pressure of the refrigeration cycle as inputs, and concurrently controls the first and second compressors ( 21   a,    21   b ), and the first and second expansion mechanisms ( 24 ,  26 ), thereby concurrently controlling the evaporating temperature of the refrigerant, the degree of superheat of the refrigerant, the gas cooler outlet temperature of the refrigerant, and the high pressure of the refrigeration cycle. 
   
   
   
       7 . The refrigeration apparatus of  claim 1 , wherein
 a plurality ones of the utilization side heat exchanger ( 27   a,    27   b ) are connected in parallel with each other,   the expansion mechanism includes a plurality of utilization side expansion mechanisms ( 26   a,    26   b ) each corresponding to the utilization side heat exchangers ( 27   a,    27   b ), and a heat source side expansion mechanism ( 24 ) provided between the utilization side heat exchangers ( 27   a,    27   b ) and expansion mechanisms ( 26   a,    26   b ), and the heat source side heat exchanger ( 23 ),   in cooling operation,
 the predetermined physical value includes evaporating temperatures of the refrigerant in the utilization side heat exchangers ( 27   a,    27   b ), and degrees of superheat of the refrigerant at the outlets of the utilization side heat exchangers ( 27   a,    27   b ), and 
 the control section ( 340 ) receives the evaporating temperatures of the refrigerant, the degrees of superheat of the refrigerant in the utilization side heat exchangers ( 27   a,    27   b ), and the high pressure of the refrigeration cycle as inputs, and concurrently controls the compression mechanism ( 21 ), the plurality of utilization side heat expansion mechanisms ( 26   a,    26   b ), and the heat source side expansion mechanism ( 24 ), thereby concurrently controlling the evaporating temperatures of the refrigerant, and the degrees of superheat of the refrigerant in the utilization side heat exchangers ( 27   a,    27   b ), and the high pressure of the refrigeration cycle. 
   
   
   
       8 . The refrigeration apparatus of  claim 1 , wherein
 a plurality ones of the utilization side heat exchanger ( 27   a,    27   b ) are connected in parallel with each other,   the expansion mechanism includes a plurality of utilization side expansion mechanisms ( 26   a,    26   b ) each corresponding to the utilization side heat exchangers ( 27   a,    27   b ), and a heat source side expansion mechanism ( 24 ) provided between the utilization side heat exchangers ( 27   a,    27   b ) and expansion mechanisms ( 26   a,    26   b ), and the heat source side heat exchanger ( 23 ),   in heating operation,
 the predetermined physical value includes a degree of superheat of the refrigerant at an outlet of the heat source side heat exchanger ( 23 ), and gas cooler outlet temperatures of the refrigerant which are temperatures of the refrigerant at outlets of the utilization side heat exchangers ( 27   a,    27   b ), and 
 the control section ( 340 ) receives the degree of superheat of the refrigerant, the gas cooler outlet temperatures of the refrigerant in the utilization side heat exchangers ( 27   a,    27   b ), and the high pressure of the refrigeration cycle as inputs, and concurrently controls the compression mechanism ( 21 ), the plurality of utilization side expansion mechanisms ( 26   a,    26   b ), and the heat source side expansion mechanism ( 24 ), thereby concurrently controlling the degree of superheat of the refrigerant, the gas cooler outlet temperatures of the refrigerant in the utilization side heat exchangers ( 27   a,    27   b ), and the high pressure of the refrigeration cycle.