JP2002310518A - Refrigerating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a refrigerating capacity from being deteriorated by securing a stable operation state in a refrigerating apparatus even when air bubbles are mixed into a liquid refrigerant in liquid refrigerant piping located at an outlet of a condenser. SOLUTION: In the refrigerating apparatus provided with a refrigeration cycle comprising a compressor, the condenser, a supercooler including a cooling means for supercooling a liquid refrigerant from the condenser, an expansion valve, and a vaporizer, a cooling means inlet of the supercooler is connected with downstream piping of the foregoing expansion valve, and an outlet of the cooling means is connected with upstream piping of the vaporizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus using a refrigerating cycle, and more particularly to a refrigerating apparatus such as an air conditioner, a refrigerator, a chiller, and a dehumidifier.

[0002]

2. Description of the Related Art The production of specific CFCs (CFC-based refrigerants) which have been used in refrigeration systems has been completely abolished since the beginning of 1996. HFC-based refrigerants have been receiving attention from the viewpoint of safety, performance, etc. as a substitute for the specified amount of specified fluorocarbons (HCFC-based refrigerants), which began to be regulated in 1996.

[0003] R134a is a typical HFC-based refrigerant,
R404A, R507A as representatives of HFC-based mixed refrigerants
And R407C, etc., compared to CFC and HCFC-based refrigerants, the compressor intake gas density is large, and the compressor inlet volume is constant, so the gas weight increases,
The refrigerant circulation amount increases, and as a result, the pressure loss in the liquid pipe increases, the degree of supercooling decreases, and the degree of saturation temperature drop increases.

[0004] Further, since the specific heat of the liquid refrigerant is larger than that of the CFC or HCFC refrigerant, the degree of subcooling of the liquid tends to be small. In addition, there is a characteristic that gas refrigerant bubbles easily melt into the liquid refrigerant portion in the liquid refrigerant sump portion of the liquid receiver or the condenser.

Since the liquid refrigerant containing many bubbles has a large specific volume, in the conventional refrigeration cycle as shown in FIG. 5, the expansion valve 3 is choked and the refrigerant circulation amount is reduced.
Accordingly, problems such as a decrease in the refrigerating capacity and a decrease in the durability of the compressor 1 due to an increase in the temperature of the gas refrigerant sucked into the compressor 1 may occur. Was.

Therefore, conventionally, measures have been taken to prevent refrigerant bubbles from entering the liquid refrigerant pipe 6 downstream of the condenser 2 in the refrigeration cycle.

A first conventional example is disclosed in Japanese Patent Laid-Open No. 6-11212.
Is disclosed in Japanese Patent Application Laid-Open Publication No. HEI 9-203 (1995). This relates to a liquid receiver that forms a refrigeration cycle, and has a guide part with a conical surface or a hemispherical outer surface with a larger diameter at the upper part on the upper part of the liquid receiver. It is guided to the inner surface below the conical portion or the hemispherical surface, travels along the cylindrical wall surface, and flows down gently into the liquid refrigerant to reduce the generation of bubbles in the liquid refrigerant.

As a second conventional example, there is a method of increasing the amount of charged refrigerant in the case of a water-cooled condenser to ensure the degree of supercooling of the liquid refrigerant.

As a third conventional example, Japanese Patent Application Laid-Open No. Hei 9-196480 discloses a method called liquid gas heat exchange in which heat is exchanged between a suction gas and a liquid refrigerant. That is,
This publication discloses an evaporator for exchanging heat with a low-temperature gas refrigerant to lower the temperature of a freezing chamber, a compressor for sucking gas refrigerant from the evaporator and compressing it, and A condenser for heat-exchanging the high-temperature and high-pressure gas refrigerant with water or the like to condense into a liquid refrigerant, a subcooler having a cooling pipe for subcooling the liquid refrigerant from the condenser, and the subcooling. An expansion valve for expanding the liquid refrigerant from the cooler into a low-temperature gaseous refrigerant, and connecting these devices with a pipe to form a refrigeration cycle. An example is shown of a refrigerating device connected to a downstream pipe of a vessel and also having a cooling pipe outlet connected to a suction pipe of the compressor.

[0010]

However, the first conventional example has a problem that the degree of supercooling of the liquid refrigerant in the liquid refrigerant pipe 6 is insufficient, and bubbles are generated again in the liquid refrigerant pipe 6. .

In the second conventional example, the expensive HF
It is necessary to enclose a large amount of the C refrigerant, and there is a problem that the cost increases.

Further, in the third conventional example closest to the present invention, a pressure loss occurs due to the liquid-gas heat exchange, the intake gas density decreases due to this effect, the refrigerant circulation amount decreases, and the refrigerating capacity decreases. For example, the decrease in the refrigerating capacity of the conventional example with respect to the standard cycle having no supercooler has a problem that the evaporation temperature is about 15% at 0 ° C. and about 10% at −40 ° C.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a refrigeration apparatus which ensures a stable operation state even if bubbles are mixed in a liquid refrigerant pipe and prevents a decrease in refrigeration capacity. To provide.

[0014]

In order to achieve the above object, a refrigeration apparatus according to the present invention is characterized by what is described in each claim of the claims. A refrigerating apparatus according to claim 1, comprising a refrigerating cycle including a compressor, a condenser, a subcooler having a cooling unit for subcooling liquid refrigerant from the condenser, an expansion valve, and an evaporator. Wherein the cooling means inlet of the supercooler is connected to the downstream pipe of the expansion valve, and the cooling means outlet is also connected to the upstream pipe of the evaporator.

[0015]

FIG. 4 is a Mollier diagram according to the present invention. The liquid refrigerant containing bubbles is in state c, the subcooler liquid refrigerant outlet is state d, the subcooler gas refrigerant inlet downstream of the expansion valve is state e, and the subcooler gas refrigerant outlet upstream of the evaporator 4 is state f. I have. Note that a represents the state of the suction port to the compressor.

In the Mollier diagram, the amount of heat exchange in the subcooler is represented by the following equation.

[0017] _{G (i c -i d) =} G (i f -i e)
(G; refrigerant circulation amount) On the other hand, the refrigerating capacity is represented by G (i _a -i _f). Here, the refrigerant circulation amount G is a constant value regardless of the presence or absence of the supercooler. In addition, the enthalpy difference relates to a refrigeration capacity (i _a -i _f)
Is also constant regardless of the presence or absence of the supercooler. That is,
The provision of the supercooler as in the present invention does not affect the refrigerating capacity at all only by liquefying bubbles in the liquid refrigerant, and has a refrigerating capacity equal to that of a standard cycle without a supercooler. The lowering of the refrigerating capacity unlike the conventional example does not occur.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIGS.

FIG. 1 is a refrigeration cycle system diagram showing a first embodiment of the present invention. The refrigerating apparatus includes a screw type or scroll type compressor 1, a condenser 2, an expansion valve 3, an evaporator 4, a subcooler 5, a liquid refrigerant pipe 6, and the like.

In FIG. 1, the subcooler 5 comprises cooling means 5a for passing liquid refrigerant from a subcooler liquid refrigerant inlet 7 to a subcooler liquid refrigerant outlet 8 on the side to be cooled, and a subcooler on the cooling side. A cooling means 5b for passing the gas refrigerant from the gas refrigerant inlet 9 to the supercooler gas refrigerant outlet 10;
Is provided on the downstream side of the condenser 2 and on the upstream side of the temperature-driven or electronically driven expansion valve 3, and the cooling means 5 b is provided on the downstream side of the expansion valve 3 and of the evaporator 4. It is provided on the upstream side.

The refrigerant flow rate adjusting means 11 comprising a temperature-sensitive cylinder and a pressure equalizing pipe of the temperature-type expansion valve closely contacts the temperature-sensitive cylinder to a pipe downstream of the evaporator 4, and controls the opening of the expansion valve 3. By this control method, a gas refrigerant having sufficient latent heat can be supplied to the evaporator 4.

With such a configuration, the gas refrigerant compressed by the compressor 1 is sent to the condenser 2 and exchanges heat with cooling water or the like to be condensed into a liquid refrigerant. Further, the liquid refrigerant containing air bubbles is completely liquefied and supercooled by the supercooler 5 provided after the outlet of the liquid from the condenser 2, and the refrigerant is sent to the expansion valve 3 and expanded to become a wet gas. The refrigerant in a wet gas state flows into the supercooler 5 again to cool the liquid refrigerant containing bubbles,
After being sent to the evaporator 4 through the refrigerant pipe and exchanging heat with the object to be cooled, it becomes a gas refrigerant and is sucked into the compressor 1.

Here, the subcooler 5 has a plate heat exchange type,
Any heat exchanger such as a shell and tube type can be used.

The subcooler liquid refrigerant inlet 7 is connected to the means 5a to be cooled.
Is cooled by the gas refrigerant which has passed through the expansion valve 3 and reached the evaporation temperature, completely liquefies the bubbles, and the liquid refrigerant flows out of the supercooler liquid outlet 8. . The liquid refrigerant flowing out of the supercooler 5 passes through the expansion valve 3, reaches an evaporation temperature, flows into the cooling means 5b from the supercooler gas inlet 9, and cools the liquid refrigerant containing the above-described bubbles.
It flows out from the supercooler gas outlet 10 and flows into the evaporator 4.

The piping between the supercooler 5 and the evaporator 4 flows a highly dry refrigerant, so that the pressure loss is reduced.
The pipe is thicker than the pipe between the condenser 2 and the subcooler 5.

FIG. 2 is a refrigerating apparatus cycle system diagram showing a second embodiment of the present invention. 2 is different from the refrigeration apparatus shown in FIG.
2 is provided. The liquid refrigerant flowing out of the receiver 12 enters the pipe on the side to be cooled, exchanges heat with the gas refrigerant on the cooling side, and supercools the liquid refrigerant. By providing the liquid receiver 12, a certain amount of refrigerant can be secured at the time of initial setting.

FIG. 3 is a refrigerating apparatus cycle system diagram showing a third embodiment of the present invention. 3 is different from the refrigeration apparatus of FIG. 1 in that the supercooler 5 also serves as the liquid receiver 12,
The liquid refrigerant stays therein. The liquid refrigerant is on the side to be cooled, and a gas refrigerant pipe through which the gas refrigerant on the cooling side passes is provided at a lower portion in the subcooler 5, and is usually immersed in the staying liquid refrigerant. When the gas refrigerant adiabatically expanded and cooled by the expansion valve 3 passes through the gas refrigerant pipe, the gas refrigerant exchanges heat with the liquid refrigerant retained in the supercooler 5 to supercool the liquid refrigerant. With the supercooler 5, the liquid receiver 12 can be omitted while having the function of the liquid receiver 12.

The air-cooled heat transfer area required for liquefaction of bubbles in the supercooler is compared with the water-cooled heat transfer area. Assuming that the operating conditions are an evaporating temperature of 0 ° C., a condensing temperature of 40 ° C., a cooling water inlet temperature of 32 ° C. and an outlet temperature of 37 ° C. in the case of a water cooling type, the heat transfer area of the supercooler required in the present invention is a water cooling type. This is only about 1/8 of the case. This is because the temperature on the cooling side in the subcooler according to the present invention is the evaporation temperature of the refrigeration cycle, and the temperature difference between the cooling side and the cooled side is large.

[0029]

As described above, according to the present invention, even if the liquid refrigerant containing bubbles flows out to the condenser liquid outlet pipe, the liquid refrigerant is completely liquefied by the supercooler, thereby preventing the expansion valve from being choked. This prevents the refrigerating capacity from lowering and allows the refrigerating capacity to maintain a stable operation as it is.

Further, in order to prevent air bubbles in the liquid refrigerant from being mixed, it is necessary to increase the amount of refrigerant charged in the liquid refrigerant reservoir of the receiver or the condenser. , The amount of refrigerant to be charged can be reduced, not only contributing to the prevention of global warming in the global environment, but also the cost of the refrigeration system can be reduced.

[Brief description of the drawings]

FIG. 1 is a cycle system diagram showing a first embodiment of the present invention.

FIG. 2 is a cycle system diagram showing a second embodiment of the present invention.

FIG. 3 is a cycle system diagram showing a third embodiment of the present invention.

FIG. 4 shows a Mollier diagram of the present invention.

FIG. 5 shows a prior art cycle system diagram.

[Explanation of Signs] 1 ... Compressor 2 ... Condenser 3 ... Expansion valve 4 ... Evaporator 5 ... Supercooler 5a ... Cooled means 5b ... Cooling means 6 ... Liquid refrigerant pipe 7 ... Supercooler liquid inlet 8 ... Super Cooler liquid outlet 9 ... Supercooler gas inlet 10 ... Supercooler gas outlet 11 ... Refrigerant flow rate adjusting means 12 ... Liquid receiver

Claims (3)

[Claims] 1. A refrigerating apparatus comprising a compressor, a condenser, a subcooler having a cooling means for subcooling a liquid refrigerant from the condenser, a refrigerating cycle having an expansion valve and an evaporator, A refrigerating apparatus, wherein a cooling means inlet of a cooler is connected to a downstream pipe of the expansion valve, and a cooling means outlet is also connected to an upstream pipe of the evaporator. 2. The refrigeration apparatus according to claim 1, wherein the refrigerant is an HFC-based refrigerant. 3. The refrigeration apparatus according to claim 1, wherein the refrigerant is an HFC-based mixed refrigerant.