JPH0443261A - Freezing device - Google Patents

Abstract

PURPOSE:To prevent heating of a low stage compressor and to improve reliability by a method wherein a high temperature high pressure refrigerant gas discharged from a high stage compressor is liquefied by a condenser and subcooled and discharged to a condenser and an intermediate cooler to branch a part thereof to the liquid injection port of the low stage compressor is provided. CONSTITUTION:Refrigerant gas discharged from a high stage compressor 2 is liquefied by a condenser 3 and subcooled and discharged to a vaporizer 5, and an intermediate cooler 9 branches a part thereof to a liquid injection port 10 of a low stage compressor 1. A refrigerant from a vaporizer 5 is compressed by a low stage compressor 1, a discharge gas temperature is increased and sucked to a high stage compressor 2 together with a refrigerant the temperature of which is reduced through liquid injection. In which case, a pressure in the injection port 10 is kept at a value between an intermediate and a middle pressure, and since the pressure of a liquid refrigerant is high, liquid injection is always effected by means of a pressure difference. By controlling an intermediate expansion valve 8 so that a low stage discharge gas temperature is adjusted to +5-+20 deg.C, temperature is adjusted to a value at which enough operation is carried out at the high stage compressor 2 also.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a two-stage compression refrigeration system having a compressor that injects liquid into a lower stage compressor during the compression process.

[Conventional technology]

The second part is a refrigerant circuit diagram showing a conventional two-stage compression type refrigeration device shown in, for example, Japanese Utility Model Application Publication No. 54-17255,
In the figure, 18 is a low-stage compressor, 2 is a high-stage compressor, 3 is a condenser, 4 is an expansion valve, 5 is an evaporator, and 6 is a solenoid valve.
9 is an intercooler, which is connected to the intermediate accumulator 11 after cooling the liquid refrigerant.

These low-stage compressor 1a, intermediate accumulator 11, high-stage compressor 2, condenser 3, intercooler 9, solenoid valve 6, expansion valve 4, and evaporator 5 are connected by a pipe line and constitute a refrigerant circuit. ing.

Further, 7 is an intermediate solenoid valve, 8 is an intermediate expansion valve, and
It is inserted into a pipe line connected between the discharge side of the i-cooler 3 and the intermediate part of the intercooler 9.

Next, I will explain the two operations. The high-temperature refrigerant sucked and compressed by the low-stage compressor 1a flows into the intermediate accumulator 11, where it is mixed with the liquid refrigerant from the intercooler 9 to become a low-temperature refrigerant, which is sucked into the high-stage compressor 2 and compressed. Condenser 3
A part of the liquid is liquefied in the intermediate electromagnetic valve 7, and is passed through the intermediate expansion valve 8, the intermediate cooler 9, and the intermediate accumulator 1.
Enter 1.

The refrigerant supercooled in the intercooler 9 passes through the electromagnetic valve 6, is reduced in pressure by the expansion valve 4, is evaporated in the evaporator 5, and returns to the low stage compressor 1.

[Invention tries to solve! II! ! Since the conventional refrigeration system is configured as described above, the high temperature discharge gas of the low stage compressor 1a is mixed with the refrigerant exiting the intercooler 9 in the intermediate accumulator 11.
In addition, at low evaporation temperatures, there was a risk that the low stage compressor la itself would overheat, causing seizure of the compressor.

This invention was made to solve the above-mentioned problems, and aims to provide a refrigeration system that eliminates the need for an intermediate accumulator, prevents overheating of the low-stage compressor, and has high reliability. do.

[Means to solve the problem]

The refrigeration system according to the present invention employs a compressor capable of injecting liquid during the suction stroke as a low-stage compressor.

[For production]

The low stage compressor in this invention uses liquid injection so that the low stage discharge refrigerant gas temperature is +2 above the low stage discharge pressure saturation temperature.
It reaches a predetermined temperature of about 0 to +40 days and is sucked into the high stage compressor.

〔Example〕

Embodiments of the refrigeration system of the present invention will be described below with reference to the drawings. FIG. 1 is a refrigerant circuit N diagram of one embodiment.

In FIG. 1, when describing the configuration, the same parts as those in FIG. 2 are given the same reference numerals, and the parts different from those in FIG. 2 will be mainly described.

As is clear from comparing Figure 1 with Figure 2,
In the figure, the intermediate accumulator 11 shown in Fig. 2 is omitted, and the low stage compressor 1 and the high stage compressor 2 are directly connected, and the low stage compressor 1 can perform liquid injection in the middle of the compression stroke. A scroll compressor or a rotary compressor is used, and 10 is a liquid injection boat of the low stage compressor 1. The other configurations are the same as in FIG. 2.

Next, the operation will be explained. The refrigerant sucked into the low stage compressor 1 from the evaporator 5 is compressed, and the temperature of the discharged gas increases. The liquid refrigerant that has exited the intercooler 9 is injected from the liquid injection port 10 during the compression stroke.

The refrigerant whose temperature has been lowered by liquid injection is sucked into the high-stage compressor 2. The following operation is the same as the conventional one.

By the way, in the case of a two-stage compression refrigerator, the high pressure, low pressure, and intermediate pressure are P.

In this formula (1), P.5. is high pressure (absolute pressure) P Hubs is intermediate pressure (absolute pressure) P tabs is low pressure (absolute pressure) It is.

The evaporation temperature is -50°C (P L −b −= at R22
0, 654cg/cd a bs condensing temperature is 3
5℃ (P H-b-= 13.6kg/cda at R22
bsP □b, =3.0 kg/CT1abs(R2
2 = -15°C).

The pressure at the injection port 10 of the low stage compressor 1 is between intermediate pressure and low pressure, and the liquid refrigerant is at high pressure, so liquid is always injected due to the pressure difference.

In addition, the intermediate pressure saturation temperature is -15°C, the temperature of the discharged gas that is not compressed is usually +20days or more of the saturation temperature, and the intermediate expansion valve 8 is set to keep the low stage discharged gas temperature within ±5 to +20°C. If the temperature is controlled, even the high-stage compressor 2 will have a temperature that allows sufficient operation.

[Effects of the Invention] As described above, according to the present invention, the low-stage compressor is equipped with a scroll or low-stage compressor that can inject liquid during the compression stroke. Not only does this eliminate the need for a large mixer, but the discharge gas temperature of the low-stage compressor is always maintained at a low temperature, which has the effect of increasing the mechanical reliability of the compressor.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram of a refrigeration system according to an embodiment of the present invention, and FIG. 2 is a refrigerant circuit diagram of a conventional refrigeration system. DESCRIPTION OF SYMBOLS 1...Low stage compressor, 2...High stage compressor, 3...Condenser, 4...Expansion valve, 5...Evaporator, 9...Intercooler, 10...・Liquid injection boat. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A low-stage compressor injects liquid refrigerant from the injection port during the compression process, mixes it with the liquid refrigerant drawn in from the condenser, and then discharges the mixture.The refrigerant discharged from the low-stage compressor is sucked in and compressed. A high-stage compressor, a condenser that condenses and liquefies the high-temperature, high-pressure refrigerant gas discharged from the high-stage compressor, and a condenser that supercools the liquefied refrigerant and discharges it to the evaporator. , and an intercooler that diverts a portion of the supercooled refrigerant to the liquid injection port of the low-stage compressor.