Refrigeration apparatus with dry ice occurrence suppression structure
A refrigeration apparatus includes: a refrigerant circuit that condenses a refrigerant discharged from a compressor, decompresses the refrigerant with a capillary tube, and causes the refrigerant to evaporate in an evaporator to exhibit a refrigeration effect, wherein, as the refrigerant in the refrigerant circuit, a mixed refrigerant containing a first refrigerant having a boiling point in an ultralow temperature range of not less than −89.0° C. and not more than −78.1° C. and carbon dioxide (R744) is enclosed, and a heater that heats at least a portion of a suction pipe through which the refrigerant that returns from the evaporator to the compressor passes is provided.
1. A refrigeration apparatus, comprising:
a refrigerant circuit that condenses a mixed refrigerant discharged from a compressor, decompresses the refrigerant with a capillary tube, and causes the mixed refrigerant to evaporate in an evaporator to exhibit a refrigeration effect, wherein
the mixed refrigerant containing a first refrigerant having a boiling point in an ultralow temperature range of not less than −89.0° C. and not more than −78.1 C and carbon dioxide (R744) is enclosed,
the refrigeration effect of not more than −80° C. is exhibited by causing the first refrigerant to evaporate in the evaporator,
a heater that heats at least a portion of a suction pipe through which the mixed refrigerant that returns from the evaporator to the compressor passes to thus retain the carbon dioxide (R744) in a liquid phase or in a gas phase or to thus melt the carbon dioxide (R744) in a solidified phase in the suction pipe is provided,
the suction pipe includes a double-pipe structure including a main pipe and connection pipes connected to respective ends of the main pipe, wherein the mixed refrigerant that returns from the evaporator to the compressor passes through the main pipe and the connection pipes, and the capillary tube is disposed in the main pipe and is pulled out through the connection pipes at the respective ends, and
the heater is directly attached to one of the connection pipes of the double-pipe structure.
2. The refrigeration apparatus according to claim 1 , wherein the mixed refrigerant further contains a second refrigerant that is soluble in the carbon dioxide (R744) at a temperature lower than a boiling point of the carbon dioxide (R744).
3. The refrigeration apparatus according to claim 1 , further comprising:
a controller that controls passage of electricity to the heater,
wherein the controller passes the electricity to the heater in a case in which a temperature of the double-pipe structure reaches or falls below a predetermined value.
4. The refrigeration apparatus according to claim 3 , wherein
the controller passes the electricity to the heater in a case in which the temperature of the double-pipe structure reaches or falls below the predetermined value and a temperature of a target to be cooled through the refrigeration effect rises with respect to a set value.
5. The refrigeration apparatus according to claim 1 , further comprising:
a high-temperature-side refrigerant circuit and a low-temperature-side refrigerant circuit, an evaporator in the high-temperature-side refrigerant circuit and a condenser in the low-temperature-side refrigerant circuit constituting a cascade heat exchanger,
wherein the double-pipe structure is provided in the low-temperature-side refrigerant circuit, and
in the low-temperature-side refrigerant circuit, the mixed refrigerant is enclosed, or the heater is provided in addition to the mixed refrigerant enclosed therein.
6. The refrigeration apparatus according to claim 1 , wherein each of the connection pipes has a shape that is prone to pressure loss.
7. The refrigeration apparatus according to claim 6 , wherein each of the connection pipes is a T-pipe.
8. The refrigeration apparatus according to claim 1 , further comprising another heater attached to another one of the connection pipes of the double-pipe structure.
9. A refrigeration apparatus, comprising:
a refrigerant circuit that condenses a mixed refrigerant discharged from a compressor, decompresses the mixed refrigerant with a capillary tube, and causes the mixed refrigerant to evaporate in an evaporator to exhibit a refrigeration effect, wherein
a double-pipe structure is provided by constituting at least a portion of a suction pipe through which the mixed refrigerant that returns from the evaporator to the compressor passes by a main pipe and connection pipes connected to respective ends of the main pipe, by disposing the capillary tube in the main pipe, and by pulling out the capillary tube through the connection pipes at the respective ends,
the mixed refrigerant containing a first refrigerant having a boiling point in an ultralow temperature range of not less than −89.0° C. and not more than −78.1 C, carbon dioxide (R744), and a second refrigerant that is soluble in the carbon dioxide (R744) at a temperature lower than a boiling point of the carbon dioxide (R744) is enclosed, and
a heater is directly attached to one of the connection pipes of the double-pipe structure.
10. The refrigeration apparatus according to claim 9 , further comprising:
a controller that controls passage of electricity to the heater,
wherein the controller passes the electricity to the heater in a case in which a temperature of the double-pipe structure reaches or falls below a predetermined value.
11. The refrigeration apparatus according to claim 10 , wherein the controller passes the electricity to the heater in a case in which the temperature of the double-pipe structure reaches or falls below the predetermined value and a temperature of a target to be cooled through the refrigeration effect rises with respect to a set value.
12. The refrigeration apparatus according to claim 9 , further comprising:
a high-temperature-side refrigerant circuit and a low-temperature-side refrigerant circuit, an evaporator in the high-temperature-side refrigerant circuit and a condenser in the low-temperature-side refrigerant circuit constituting a cascade heat exchanger,
wherein the double-pipe structure is provided in the low-temperature-side refrigerant circuit, and
in the low-temperature-side refrigerant circuit, the mixed refrigerant is enclosed, or the heater is provided in addition to the mixed refrigerant enclosed therein.
13. The refrigeration apparatus according to claim 9 , wherein each of the connection pipes has a shape that is prone to pressure loss.
14. The refrigeration apparatus according to claim 13 , wherein each of the connection pipes is a T-pipe.
15. The refrigeration apparatus according to claim 9 , further comprising another heater attached to another one of the connection pipes of the double-pipe structure.