JPS6146859A - dual refrigeration equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a binary refrigeration system that combines a high-temperature side refrigeration cycle and a low-temperature side refrigeration cycle, and particularly improves oil return in the lower side refrigeration cycle. Regarding structure.

[Background of the invention]

FIG. 2 shows a cycle system diagram of a conventional dual refrigeration system. This binary refrigeration system consists of a high temperature side compressor 1, a condenser 2
, a high temperature side refrigeration cycle consisting of a capillary tube 3, a cascade condenser 4, and piping connecting these devices, a low temperature side compressor 5, an oil separator 6, the cascade condenser 4, a capillary tube 7, an evaporator 8, an accumulator 9, and The structure is a combination of piping connecting these devices and a low-temperature side refrigeration cycle.

To explain the operation of this binary refrigeration system, in the high temperature side refrigeration cycle, the refrigerant discharged from the high temperature side condenser 1 is transferred to the condenser 2.
After being liquefied in the capillary tube 3 and depressurized in the capillary tube 3, it is evaporated and exchanged in the cascade condenser 4, and then returned to the high-bulk 11t + rice compressor 1 again, and the cycle is repeated.

On the other hand, in the low-width side refrigeration cycle, the refrigerant discharged from the low-temperature side compressor 5 has oil separated in the oil separator 6, is condensed and liquefied in the cascade condenser 4, is depressurized in the cabillary nitride 7, and is transferred to the evaporator. At 8, it exchanges heat with the object to be cooled, evaporates, passes through the accumulator 9 and returns to the low-temperature side compressor 5, and the cycle is repeated.

By the way, in the above-mentioned binary refrigeration system, the evaporation temperature of the refrigerant in the evaporator 8 generally ranges from 150°C to -90°C, making it difficult to return the refrigeration oil. An oil separator 6 is attached to the discharge side of the compressor 5 to prevent refrigerating machine oil from flowing to the low pressure side. However, even if the oil separator 6 is provided, it is difficult to achieve 100% oil separation, and some oil ends up flowing into the low pressure side. The oil flowing into the low pressure side is separated, and the high molecular component oil in particular solidifies or becomes gel due to the low temperature, and tends to clog the capillary tube 7, evaporator 8, and accumulator 9. As a result, the refrigeration cycle may become blocked and become inoperable.

As a countermeasure against this problem, a method is to periodically stop the operation of the refrigeration equipment, wait for the low-pressure side equipment to rise to a predetermined temperature (a temperature at which solidified or gelled refrigeration oil flows easily), and then start operation again. However, this has the problem that it takes a considerable amount of time for the low-pressure side equipment to rise to a predetermined temperature, and the temperature of the cooled object increases.

[Purpose of the invention]

The object of the present invention is to fix the low-pressure side FEl of refrigerating machine oil that solidifies and gels on the low-pressure side while the operation continues! It is an object of the present invention to provide a dual refrigeration system that can promote the return to the li machine and prevent inoperability due to blockage of the refrigeration cycle and rise in temperature of objects to be cooled.

[Summary of the invention]

The present invention provides a low temperature 1111a in the low temperature side refrigeration cycle.
A bypass pipe is provided that branches from the connecting pipe between the E-compressor and the cascade condenser and connects to the connecting pipe between the capillary tube and the evaporator, and the bypass pipe is equipped with a pressure reducing device and a solenoid valve that periodically opens for a short period of time. The discharged gas is passed through the bypass pipe to the outlet side of the capillary tube, and the heat of the discharged gas is used to solidify it in a short time.
This system raises the temperature of gelled refrigerating machine oil to promote the return of the oil to the compressor.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG. FIG. 1 shows a cycle diagram of a dual refrigeration system according to the present invention. As shown in Fig. 2, this binary refrigeration system consists of a high-pressure side refrigeration cycle consisting of a high-pressure side compressor 1, a condenser 2, a capillary tube 3, a cascade condenser 4, and piping connecting these devices, and a low-pressure side compressor. 5, oil separator 6,
It has a configuration in which a cascade condenser 4, a capillary tube 7, an evaporator 8, an akicomulator 9, and a low-temperature side refrigeration cycle consisting of piping connecting these devices are combined. Further, in the low temperature side refrigeration cycle, a bypass pipe 10 is provided which branches from the connection pipe between the low temperature side compressor 5 and the cascade condenser 4 and connects to the connection pipe between the capillary tube and the evaporator 8. A solenoid valve 11 and a pressure reducing device 12 are interposed in the valve 10 . The solenoid valve 11 is periodically controlled to open only for a short period of time (eg, 2 minutes every 2 hours).

A capillary tube and a capacity adjustment valve are used as the pressure reducing device 12, and the illustration shows an example using a capillary tube. Further, the pressure reducing device 12 includes the electromagnetic valve 11
is opened and the discharge gas flows through the bypass pipe 10 to the low pressure side, the pressure on the low pressure side increases too much and the low pressure side compressor 5
The aperture is adjusted to prevent overload operation.

Since the present invention has the above-described configuration, when the high-pressure side refrigeration cycle and the low-pressure side refrigeration cycle are in operation, the solenoid valve 11 of the bypass pipe 10 is periodically opened, so that the discharge gas is decompressed by the pressure reducing device 12. When the gas flows through the bypass pipe 10 to the outlet side of the capillary tube 7, the temperature of the capillary tube rises in a short time due to the heat of the discharged gas. This solidifies on the low pressure side,
The gelled refrigerating machine oil is in a state where it easily flows out, and furthermore, as the low pressure increases, the temperature of the evaporator 8 and accumulator 9 rises, and the flow rate of the refrigerant is also fast, so the refrigerating machine oil quickly flows to the low pressure side. Return to compressor 5. Furthermore, since the time during which the discharged gas flows through the bypass pipe 10 is short, there is almost no rise in temperature of the object to be cooled.

〔Effect of the invention〕

Based on the above explanation, according to the present invention, by periodically moving the discharge gas to the low pressure side in the low pressure side refrigeration cycle, the refrigerating machine oil that has solidified and gelled on the low pressure side is made to flow easily. Since the return of the refrigerating machine oil to the low-pressure side compressor is promoted, it is possible to prevent operation failure due to blockage of the refrigerating cycle. In addition, since the discharge gas flows into the low pressure side for a short time, it hardly increases the temperature of the cooled object.

[Brief explanation of the drawing]

FIG. 1 is a cycle system diagram showing the dual refrigeration system of the present invention,
FIG. 2 is a cycle diagram of a conventional dual refrigeration system. 5...Low pressure side compressor 7...Capillary tube
8... Evaporator 10... Bypass piping 11...
Solenoid valve number? flash

Claims (1)

[Claims] A binary refrigeration system that combines a high-temperature side refrigeration cycle consisting of a high-temperature side compressor, a condenser, a capillary tube, and a cascade condenser, and a low-temperature side refrigeration cycle consisting of a low-temperature side compressor, the cascade condenser, a capillary tube, and an evaporator. In the low temperature side refrigeration cycle,
A bypass pipe is provided that branches from the connection pipe between the low-temperature side compressor and the cascade condenser and connects to the connection pipe between the capillary tube and the evaporator, and the bypass pipe is equipped with a pressure reducing device and a solenoid valve that periodically opens for a short period of time. A binary refrigeration device characterized by having: