Air conditioning apparatus

Abstract

It is an object of this invention to provide an air conditioning apparatus using supercritical refrigerant for easily regulating the circulation amount of refrigerant. A refrigeration apparatus ( 1 b ) uses refrigerant operating in the supercritical zone. The refrigeration apparatus ( 1 b ) includes a compressor ( 21 ), a first heat exchanger ( 23 ), a first expansion mechanism (V 2 ), a subcooling heat exchanger ( 24 ), a second expansion mechanism (V 3 ), a second heat exchanger ( 31 ) and a control section ( 5 ). The compressor is configured to compress the refrigerant. The first heat exchanger is configured to cool the high-pressure refrigerant compressed by the compressor. The first expansion mechanism is configured to decompress the refrigerant to critical pressure or less. The subcooling heat exchanger is configured to subcool the refrigerant decompressed by the first expansion mechanism. The second expansion mechanism is configured to decompress the refrigerant cooled by the subcooling heat exchanger to low pressure. The second heat exchanger is configured to heat the refrigerant decompressed by the second expansion mechanism. The control section is configured to conduct first control to regulate the first and second expansion mechanisms for storing the refrigerant of a liquid state in the subcooling heat exchanger.

1 . A refrigeration apparatus using refrigerant operating in a supercritical zone of the refrigerant, comprising:
 a compressor configured to compress the refrigerant;   a first heat exchanger configured to cool the refrigerant compressed by the compressor;   a first expansion mechanism configured to decompress the refrigerant to critical pressure or less;   a subcooling heat exchanger configured to subcool the refrigerant decompressed by the first expansion mechanism;   a second expansion mechanism configured to decompress the refrigerant cooled by the subcooling heat exchanger;   a second heat exchanger configured to heat the refrigerant decompressed by the second expansion mechanism; and   a control section configured to conduct a first control, in which the first and second expansion mechanisms are regulated in order to store the refrigerant in a liquid state in the subcooling heat exchanger.   
   
   
       2 . The refrigeration apparatus according to  claim 1 , further comprising
 a subcooling information obtaining section configured to obtain subcooling information used to calculate a degree of subcooling of the refrigerant in the subcooling heat exchanger, wherein   the control section is further configured to calculate the degree of subcooling based on the subcooling information, and   the first control is conducted based on the degree of subcooling.   
   
   
       3 . The refrigeration apparatus according to  claim 2 , wherein
 the subcooling information obtaining section includes an inlet temperature sensor configured to detect a refrigerant inlet temperature of the subcooling heat exchanger and an outlet temperature sensor configured to detect a refrigerant outlet temperature of the subcooling heat exchanger.   
   
   
       4 . The refrigeration apparatus according to  claim 2 , wherein
 the subcooling information obtaining section includes an inlet pressure sensor configured to detect a refrigerant inlet pressure of the subcooling heat exchanger and an outlet temperature sensor configured to detect a refrigerant outlet temperature of the subcooling heat exchanger.   
   
   
       5 . A refrigeration apparatus using refrigerant operating in a supercritical zone of the refrigerant, comprising:
 a compressor configured to compress the refrigerant;   a first heat exchanger configured to conduct heat exchange of the refrigerant;   a first expansion mechanism configured to decompress the refrigerant;   a subcooling heat exchanger configured to subcool the refrigerant;   a second expansion mechanism configured to decompress the refrigerant;   a second heat exchanger configured to conduct heat exchange of the refrigerant;   a switch mechanism configured to switch between a first condition and a second condition,
 the first condition being configured to cause the refrigerant evaporated in the second heat exchanger to flow into the compressor and to cause the refrigerant compressed in the compressor to flow into the first heat exchanger, and 
 the second condition being configured to cause the refrigerant evaporated in the first heat exchanger to flow into the compressor and to cause the refrigerant compressed in the compressor to flow into the second heat exchanger; and 
   a control section configured to conduct a first control and a second control,
 the first control being configured to cause the first expansion mechanism to decompress the refrigerant from high pressure to intermediate pressure equal to or less than the supercritical pressure and to cause the second expansion mechanism to decompress the intermediate pressure refrigerant subcooled by the subcooling heat exchanger to low pressure in order to store the refrigerant in a liquid state in the subcooling heat exchanger when the switch mechanism is in the first condition, and 
 the second control being configured to cause the second expansion mechanism to decompress the refrigerant from high pressure to the intermediate pressure equal to or less than the supercritical pressure and to cause the first expansion mechanism to decompress the intermediate pressure refrigerant subcooled by the subcooling heat exchanger to low pressure in order to store the refrigerant in the liquid state in the subcooling heat exchanger when the switch mechanism is in the second condition. 
   
   
   
       6 . The refrigeration apparatus according to  claim 5 , further comprising
 a subcooling information obtaining section configured to obtain subcooling information used to calculate a degree of subcooling of the refrigerant in the subcooling heat exchanger, wherein   the control section is further configured to calculate the degree of subcooling based on the subcooling information, and   the first control or the second control is conducted based on the degree of subcooling.   
   
   
       7 . A refrigeration apparatus using refrigerant operating in a supercritical zone of the refrigerant, comprising:
 a heat source unit including a compressor configured to compress the refrigerant and a heat source side heat exchanger configured to conduct heat exchange between the refrigerant and a first fluid;   a first expansion mechanism configured to decompress the refrigerant;   a heat source side auxiliary heat exchanger configured to conduct heat exchange of the refrigerant;   a second expansion mechanism configured to decompress the refrigerant; and   a switch mechanism configured to switch between a first condition and a second condition,
 the first condition being configured to cause the refrigerant to flow into the compressor after a utilization side heat exchanger conducts heat exchange of the refrigerant and to cause the refrigerant compressed by the compressor to flow into the heat source side heat exchanger, and 
 the second condition being configured to cause the refrigerant to flow into the compressor after the heat source side heat exchanger conducts the heat exchange of the refrigerant and to cause the refrigerant compressed by the compressor to flow into the utilization side heat exchanger; 
   a utilization unit including the utilization side heat exchanger, which is configured to conduct heat exchange of the refrigerant, a third expansion mechanism configured to decompress the refrigerant, and a utilization side auxiliary heat exchanger configured to conduct heat exchange of the refrigerant; and   a control section configured to conduct a first control, a second control and a third control,
 the first control being configured to cause the heat source side auxiliary heat exchanger to function as a subcooler and to regulate the first and second expansion mechanisms in order to store the refrigerant in a liquid state in the heat source side auxiliary heat exchanger when temperature of the first fluid is less than a critical temperature of the refrigerant when the switch mechanism is in the first condition, 
 the second control being configured to cause the utilization side auxiliary heat exchanger to function as a subcooler and to regulate the second and third expansion mechanisms in order to store the refrigerant in the liquid state in the utilization side auxiliary heat exchanger when temperature of the first fluid is equal to or greater than the critical temperature of the refrigerant when the switch mechanism is in the first condition, and 
 the third control being configured to cause the utilization side auxiliary heat exchanger to function as a subcooler and to regulate the second and third expansion mechanisms in order to store the refrigerant in the liquid state in the utilization side auxiliary heat exchanger when the switch mechanism is in the second condition. 
   
   
   
       8 . The refrigeration apparatus according to  claim 7 , wherein
 the heat source unit further includes a heat source side subcooling information obtaining section configured to detect a first subcooling degree of the heat source side auxiliary heat exchanger,   the utilization unit further includes a utilization side subcooling information obtaining section configured to detect a second subcooling degree of the utilization side auxiliary heat exchanger,   the first control is conducted based on the first subcooling degree, and   the second and third controls are conducted based on the second subcooling degree.   
   
   
       9 . The refrigeration apparatus according to  claim 8 , wherein
 the heat source side subcooling information obtaining section includes a first inlet temperature sensor configured to detect a refrigerant inlet temperature of the heat source side auxiliary heat exchanger and a first outlet temperature sensor configured to detect a refrigerant outlet temperature of the heat source side auxiliary heat exchanger.   
   
   
       10 . The refrigeration apparatus according to  claim 9 , wherein
 the utilization side subcooling information obtaining section includes a second inlet temperature sensor configured to detect a refrigerant inlet temperature of the utilization side auxiliary heat exchanger and a second outlet temperature sensor configured to detect a refrigerant outlet temperature of the utilization side auxiliary heat exchanger.   
   
   
       11 . The refrigeration apparatus according to  claim 7 , wherein
 the refrigerant is carbon dioxide refrigerant.   
   
   
       12 . The refrigeration apparatus according to  claim 8 , wherein
 the utilization side subcooling information obtaining section includes an inlet temperature sensor configured to detect a refrigerant inlet temperature of the utilization side auxiliary heat exchanger and a second outlet temperature sensor configured to detect a refrigerant outlet temperature of the utilization side auxiliary heat exchanger.   
   
   
       13 . The refrigeration apparatus according to  claim 1 , wherein
 the refrigerant is carbon dioxide refrigerant.   
   
   
       14 . The refrigeration apparatus according to  claim 5 , wherein the refrigerant is carbon dioxide refrigerant.