JPH0713550B2 - Refrigeration cycle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultra-low temperature refrigerating cycle by a non-azeotropic mixed refrigerant refrigerating cycle, and in particular, it rapidly compresses refrigerating machine lubricating oil accumulated in an ultra-low temperature portion (near the cooler). The present invention relates to a refrigeration cycle suitable for returning to the machine.

(Prior Art) As a refrigeration cycle as described above, there is one as shown in FIG.

That is, this refrigeration cycle includes a compressor 1 for compressing a non-azeotropic mixed refrigerant, and an oil separator 2 provided on the discharge side of the compressor 1.
A condenser 3 for cooling the high temperature and high pressure refrigerant discharged from the compressor 1, a gas-liquid separator 4 for separating the cooled non-azeotropic mixed refrigerant into a liquid phase refrigerant and a gas phase refrigerant, and a liquid phase The first expansion mechanism 5 for decompressing the refrigerant, the cascade condenser 6 for exchanging heat between the refrigerant decompressed and cooled by the first expansion mechanism 5 and the separated vapor phase refrigerant, and the cooled vapor phase refrigerant for the second It comprises a cooler (evaporator) 8 that is decompressed and cooled by the expansion mechanism 7 and cools the object to be cooled to an ultralow temperature.

By the way, in such an ultra low temperature refrigeration cycle, the lubricating oil (hereinafter referred to as oil) used in the compressor 1 is discharged into the refrigeration cycle together with the refrigerant, and the oil is cooled below this pour point in the ultra low temperature portion to achieve fluidity. If the cooling performance deteriorates due to loss of oil and clogging of the piping, stop the operation of the refrigeration cycle and wait until the temperature of the ultra-low temperature part rises above the pour point of the oil to restart the operation, and remove the clogged oil from the compressor. It was poured away to 1 to recover the cooling performance.

(Problems to be solved) However, this method has a drawback that it takes time to raise the temperature and the temperature in the refrigerator also rises due to the heat of penetration during that time.

The present invention provides a refrigeration cycle capable of promptly recovering the cooling performance of the ultra-low temperature refrigeration cycle, which is deteriorated due to the oil clogging in the ultra-low temperature portion.

(Means and Actions for Solving the Problem) In the refrigeration cycle of the present invention, in the ultra-low temperature portion, the oil discharged from the compressor together with the refrigerant is cooled to a temperature below the pour point, loses fluidity, accumulates, and cools. When performance deteriorates, high-temperature uncondensed refrigerant (hereinafter referred to as hot gas) is caused to flow through the bypass pipe to the ultra-low temperature part, thereby quickly recovering oil fluidity and eliminating pipe clogging, and recovering cooling performance. To do.

Especially in the non-azeotropic mixed refrigerant refrigeration cycle, after gas-liquid separation,
Most of the oils have high boiling point components (eg R11,
R12) dissolves in the high temperature side cycle refrigerant containing a large amount of R12), and the gas phase contains little. Since the temperature of the vapor phase is higher than the pour point of oil, the vapor phase separated by the gas-liquid separator is suitable for use as hot gas.

Embodiment An embodiment according to the present invention will be described below with reference to FIG.

FIG. 2 is an example of a non-azeotropic mixed refrigerant refrigeration cycle.

During normal operation, the first solenoid valve 18 is closed and the second solenoid valve 19 is open. The refrigerant gas discharged by the compressor 10 is an oil separator 11
After most of the oil is separated by, it is cooled in the condenser 12,
The gas-liquid separator 13 separates into a gas phase. Here, as shown in FIG. 3, the liquid phase is low in low boiling point components (rich in high boiling point components), and the gas phase is rich in low boiling point components. Accordingly, the liquid phase is decompressed by the first expansion mechanism 14 as a refrigerant in the high temperature side cycle and becomes a low temperature, and the cold heat is consumed by the cascade condenser 15 to condense the constant temperature side refrigerant in the vapor phase and evaporates.

On the other hand, the refrigerant of the low temperature side condensed by the cascade condenser 15 is decompressed by the second expansion mechanism 16 and generates an ultra low temperature by the cooler 17 to be evaporated.

The evaporated refrigerant returns to the compressor 10 through the suction pipe 21 to complete the refrigeration cycle.

Next, when the oil discharged from the compressor 10 accumulates in the ultra-low temperature portion during long-time operation and the cooling performance of the refrigeration cycle deteriorates, the first solenoid valve 18 is opened and the second solenoid valve 19 is closed. The hot gas separated by the gas-liquid separator 13 is caused to flow through the bypass pipe 20 to the second expansion mechanism 16 on the low temperature side, and the temperature of the accumulated oil is raised by the high temperature to restore the fluidity of the oil and push it to the compressor 10. Of. As a result, the cooling performance of the refrigeration cycle is quickly restored. At this time, a hot gas cycle (gas cycle) is performed in the circuit including the compressor 10, the gas-liquid separator 13, the bypass pipe 20, the second expansion mechanism 16, and the cooler 17.
Are formed.

The operation of the hot gas is performed by a timer at regular intervals of operation, or by detecting or predicting oil clogging by an appropriate means such as measuring a change in pressure loss between the inlet and the outlet of the cooler 17.

Also, as shown in FIG. 4, the first and second expansion mechanisms are provided with thin tubes 30,3.
Alternatively, the hot gas may flow in the middle of the thin tube 31. By doing so, the flow path resistance due to the thin tube 31 is reduced, and the flow rate of the refrigerant during the gas cycle can be secured. Further, in the decompression mechanism by the thin tube 31, the temperature near the outlet is extremely low and the temperature near the inlet is relatively high, so the temperature of the hot gas is effectively transmitted to the oil accumulated in the ultra-low temperature portion, and the fluidity is quickly restored. be able to.

In addition, as shown in FIG.
You may let me have. In FIG. 5, reference numeral 32 corresponds to the first expansion mechanism 14 (or the thin tube 30), and reference numeral 34.
Corresponds to the second expansion mechanism 16 (or the high pressure side half of the thin tube 31).

Next, a non-azeotropic mixed refrigerant refrigeration cycle having two or more gas-liquid separators not described above will be described.

In a non-azeotropic mixed-refrigerant refrigeration cycle having two or more gas-liquid separators, as shown in FIG. 6, an example of the hot gas separated by the first-stage gas-liquid separator 35 is shown as in FIG. The same effect can be obtained by providing and operating the above-mentioned hot gas bypass pipe 20 that flows (effect) As described above, the oil discharged from the compressor 10 due to the operation of the ultra low temperature refrigeration cycle for a long time is in the ultra low temperature portion. In order to reduce the cooling performance of the refrigeration cycle due to accumulation, the temperature of the oil is raised by flowing hot gas to restore fluidity and push it to the compressor 10. The refrigeration cycle performance is recovered in a short time as compared with the case where the fluidity of the oil is recovered by stopping and then increasing the temperature from the high pressure side of the cycle and the invasion heat from the surroundings. Therefore, according to the method of the present invention, the rise in the temperature inside the chamber due to the time for recovering the fluidity of the oil can be reduced as compared with the conventional method.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a conventional non-azeotropic mixed refrigerant cycle. 2 to 6 show an embodiment of the present invention, FIG. 2 is a circuit diagram of a refrigeration cycle using a non-azeotropic mixed refrigerant, and FIG. 3 is a component concentration of the non-azeotropic mixed refrigerant in a gas phase and a liquid phase. 4 and 5 are circuit diagrams of another embodiment of the present invention, and FIG. 6 is a non-azeotropic mixed refrigerant refrigeration cycle having two or more gas-liquid separators. It is a circuit diagram in a case. In the figure, 1,10 ... compressor, 2,11 ... oil separator, 3,12
...... Condenser, 6,15 …… Cascade condenser, 5,14,30,
32 …… First expansion mechanism, 7,16,31,34 …… Second expansion mechanism, 33
...... 3rd expansion mechanism, 8,17 ...... Cooler, 4,18,35 …… Gas-liquid separator, 21 …… Suction pipe, 18 …… First solenoid valve, 19 …… Second
Solenoid valve, 20 ... Bypass pipe.

Continuation of the front page (56) Reference JP-A-55-110860 (JP, A) JP-A-48-72742 (JP, A) Actually opened 56-134562 (JP, U) Actually opened 56-149861 (JP , U)

Claims (3)

[Claims] 1. A compressor for compressing a non-azeotropic mixed refrigerant, and a condenser for cooling the non-azeotropic mixed refrigerant discharged from the compressor.
A gas-liquid separator for separating a non-azeotropic mixed refrigerant cooled by a condenser into a liquid-phase refrigerant having a high boiling point component and a gas-phase refrigerant having a high boiling point component, and a first depressurizing the separated liquid-phase refrigerant An expansion mechanism and a cascade condenser that cools the separated vapor-phase refrigerant by the refrigerant that has been decompressed and cooled by the first expansion mechanism, and the refrigerant from the first expansion mechanism that has passed through the cascade condenser is returned to the compressor. On the other hand, in the refrigeration cycle including a second expansion mechanism that depressurizes the vapor-phase refrigerant cooled by the cascade condenser and a cooler that cools the cooled object by the refrigerant depressurized and cooled by the second expansion mechanism, A bypass pipe provided between the gas phase outlet of the liquid separator and the high-pressure side of the cooler and bypassing the cascade condenser; and a first solenoid valve capable of opening and closing the bypass pipe,
A second solenoid valve capable of opening and closing a pipe line from the gas phase outlet of the gas-liquid separator to the second expansion mechanism via the cascade condenser, and the first solenoid valve is closed during normal cooling operation;
The refrigeration cycle described above, wherein the second solenoid valve is open, and when removing the oil accumulated near the cooler, the first solenoid valve is opened and the second solenoid valve is closed. . 2. The refrigeration cycle according to claim 1, wherein the second expansion mechanism is composed of a thin tube, and the outlet of the bypass tube is connected to an intermediate portion of the thin tube. 3. The refrigeration cycle according to claim 1, wherein a third expansion mechanism is connected to the bypass pipe, and the outlet of the bypass pipe is connected to the low pressure side of the second expansion mechanism.