JPH0452614Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention particularly relates to an improvement of a dual refrigeration system that prevents lubricating oil from adhering and staying in the piping of the low-temperature side refrigeration cycle.

(Prior art) Conventionally, dual refrigeration systems have been used to cool the condenser of the low-temperature side refrigeration cycle with the evaporator of the high-temperature side refrigeration cycle, thereby cooling the freezer to an extremely low temperature that cannot be reached with a simple refrigeration cycle. There is. In this case, if the operation continues for a long period of time, the refrigerant will be deposited in the vicinity of the piping connections at the capillary inlet and outlet of the pressure reducing device of the low-temperature side refrigeration cycle, in other words, in the areas where the refrigerant flow rate suddenly slows down or the refrigerant flow stagnates. At the same time, the circulating lubricating oil turns into wax and adheres to it. As a result, the flow of refrigerant is obstructed, resulting in a reduction in refrigerating capacity.

In order to prevent this, a binary refrigeration system as shown in FIG. 2 has been proposed. This device includes a high temperature side refrigeration cycle 14 consisting of a high temperature side compressor 1, a condenser 2, a pressure reducing device 3, and an evaporator 4 forming a cascade condenser 9, and a low temperature side compressor 5 and a condenser forming a cascade condenser 9. 6, a low-temperature side refrigeration cycle 15 consisting of a pressure reducing device 7 and an evaporator 8;
In the low-temperature side refrigeration cycle 15, a bypass branched from the high-pressure side path 12 between the low-temperature side compressor 5 and the condenser 6 and connected to the low-pressure side path 13 between the pressure reducing device 7 and the evaporator 8. It includes a pipe 11 and a valve 10 that is interposed in the bypass pipe 11 and opens and closes intermittently. Then, in order to prevent the lubricating oil from turning into wax, the valve 10 is opened for a predetermined period of time, and the low-pressure side devices 7, 8, etc. are heated by the high-temperature refrigerant from the low-temperature side compressor 5, thereby compressing the lubricating oil on the low-temperature side. We are trying to encourage passengers to return to aircraft 5.

(Problem to be Solved) However, in the above-mentioned binary refrigeration system, since the downstream side of the bypass pipe 11 is connected to the discharge side of the pressure reducing device 7, clogging of the evaporator 8 due to waxing of the lubricating oil occurs for a short time. However, since it takes time for the pressure reducing device 7 to rise in temperature, the opening time of the valve 10 must be set for a long time.
There is a problem in that the temperature of the object to be cooled increases accordingly.

The present invention has been made in view of the above-mentioned circumstances, and is intended to provide a binary refrigeration system that can eliminate clogging of the pressure reducing device 7 in a short period of time.

(Means for Solving the Problems) The present invention is characterized in that the bypass pipe is brought into contact with the pressure reducing device of the low temperature side refrigeration cycle so as to be able to freely exchange heat.

(Function) Before the lubricating oil mixed into the refrigerant due to refrigeration operation turns into wax and adheres to the low-pressure side equipment (pressure reducer, evaporator), etc. of the low-temperature side refrigeration cycle, the valve 10 opens, and the high temperature from the low-temperature side compressor is removed. The refrigerant is circulated through a bypass pipe. As a result, the temperature of the low-pressure side equipment of the low-temperature side refrigeration cycle rises in a short time, preventing the lubricating oil from turning into wax, and promoting the return of refrigerant to the low-temperature side compressor.

(Example) Hereinafter, FIG. 1, which is an example of the present invention, will be described. This binary refrigeration system includes a high temperature side refrigeration cycle 14 and a low temperature side refrigeration cycle 15, as shown in FIG.
In FIG. 1, the same reference numerals as in FIG. 2 indicate the same configuration. Therefore, the difference between this embodiment, FIG. 2, and the conventional example is that the bypass pipe 11 is in contact with the pressure reducing device 7 so as to freely exchange heat.

In this embodiment, the valve 10 is a solenoid valve, and is opened by being energized periodically or arbitrarily. The means for switching the energization may be a timer (not shown) or a temperature sensor attached to the evaporator 8 or the like that indicates the operating characteristics of the low temperature side refrigeration cycle. Further, a restriction for flow rate adjustment may be provided in the bypass pipe 11, and the pressure reducing device 7 (capillary tube in the embodiment) may be used as an expansion valve.

Therefore, the lubricating oil mixed in the refrigerant turns into wax and adheres to the wall surface near the inlet and outlet of the pressure reducing device 7, which causes the refrigerant flow rate to slow down or stagnate in the refrigerant piping of the low-temperature side refrigeration cycle 15. too,
By bypassing the high temperature refrigerant discharged from the low temperature side compressor 5, the temperature of the low pressure side path 13 including the pressure reducing device 7 is increased, and the wax is melted and fluidized. In addition, bypassing the high-temperature refrigerant increases the apparent load, and by increasing the suction side pressure and increasing the amount of refrigerant circulation, the wax is flowed and removed.

(Effects) As described above, in the present invention, the bypass pipe 11 is brought into contact with the pressure reducing device 7 in a manner that enables heat exchange. , can melt, flow and remove wax in a short time. Therefore, not only stable refrigeration operation can be performed for a long time, but also the temperature of the object to be cooled can be stabilized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a refrigeration cycle showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional refrigeration cycle. 1... High temperature side compressor, 2... Condenser, 3... Pressure reducing device, 4... Evaporator, 5... Low temperature side compressor, 6
... Condenser, 7 ... Pressure reducing device, 8 ... Evaporator, 9
...Cascade capacitor, 10...Valve, 11...
...Bypass pipe, 12...High pressure side path, 13...Low pressure side path, 14...High temperature side refrigeration cycle, 15...
...Low temperature side refrigeration cycle.

Claims (1)

[Scope of utility model registration request] A high temperature side refrigeration cycle consisting of a high temperature side compressor, a condenser, a pressure reducing device, and an evaporator forming a cascade condenser, and a low temperature side refrigeration cycle consisting of a low temperature side compressor, a condenser forming the cascade condenser, a pressure reducing device, and an evaporator. a bypass branched from a high pressure side path between the low temperature side compressor and the cascade condenser and connected to a low pressure side path between the pressure reducing device and the evaporator in the low temperature side refrigeration cycle; In a binary refrigeration system comprising a pipe and a valve interposed in the bypass pipe and operated to open and close intermittently, the bypass pipe is brought into contact with the pressure reducing device of the low-temperature side refrigeration cycle so as to freely exchange heat. The dual refrigeration device is characterized by: