JPH09196480A - Liquid refrigerating apparatus for refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely obtain a specified liquid super-cooling degree by a method wherein a by-pass circuit is provided on a refrigerant liquid piping, and a liquid refrigerating apparatus which refrigerates a refrigerant liquid by vacuumizing one part of the refrigerant liquid of a high pressure, of the total refrigerant circulation amount, and evaporating it, with the evaporation latent heat, is provided for the refrigerating of the refrigerant liquid. SOLUTION: This liquid refrigerating apparatus also works as a receiver tank 4, and a refrigerant liquid stays inside. Also, at a lower part in the liquid refrigerating apparatus 3, a refrigerating pipe 7 is provided, and normally, the refrigerating pipe 7 is immersed in the refrigerant liquid. When a compressor suction gas of a low temperature passes through the refrigerating pipe 7, the gas heat-exchanges with the liquid staying in the liquid refrigerating apparatus 3, and the liquid is super-cooled. By this method, the specified super-cooling degree of the refrigerant liquid can be stabilized, and a flush gas in the liquid piping can be prevented from generating, and a stable operation state can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid cooler for a refrigeration system.

[0002]

2. Description of the Related Art Specified CFCs (CFC-based refrigerants) that have been used in refrigeration systems have been completely abolished since the beginning of 1996. Specified CFCs (HCFC-based refrigerants) have been regulated for total production in 1996. As an alternative to these, HFC-based refrigerants are attracting attention in terms of safety and performance,
Among them, refrigerants for refrigeration systems are R404A and R507.
The two types are influential.

The air-cooling type refrigerating apparatus does not have a mechanism for cooling the refrigerant liquid, or an air-cooling liquid cooler is added to the air-cooling condenser if necessary, and the refrigerant liquid condensed in the air-cooling condenser is cooled by the air-cooling liquid. The refrigerant liquid was supercooled by sending it into a cooler and cooling the refrigerant liquid with ambient air.

[0004]

Specified CFCs (CFCs) and designated CFCs (HCFCs) that have been used in refrigeration systems.
Since a refrigerant that could be used as an alternative refrigerant has not been determined, research and development of an alternative refrigerant is underway, while
From the beginning of the year, designated CFCs (CFCs), whose production has been abolished, have been converted to designated CFCs (HCFCs).

The technology for the conversion has already been established, and refrigerating machines for HCFC and others are put on the market by refrigerating machine makers.

However, the designated CFC (HCFC) is 19
Since the total amount regulation started in 1996, it has been necessary to promote the conversion to alternative refrigerants.
Two types of HFC refrigerants, R404A and R507, are currently dominant in terms of performance and the like.

A comparison of both R404A and R507 refrigerants with R22, which is the most commonly used HCFC refrigerant at present, is as follows.

Comparing the refrigerant circulation amounts in the same ring theory refrigeration cycle with the compressor displacement volume kept constant, R2 is
R404A and R507 are larger than R2.

The specific heat of each liquid is R22 with respect to R22.
404A and R507 are larger.

As an example, an evaporation temperature of -5 ° C. and a condensation temperature of 48
℃, compressor suction gas temperature 0 ℃, decompression device inlet liquid supercooling degree 0 deg, the refrigerant circulation amount is R22, R40
4A is approximately 1.4 times, R507 is approximately 1.5 times, and the specific heat of the liquid is approximately 1.3 times that of R22 for both R404A and R507. Further, R404A and R507 have smaller liquid densities and viscosities than R22, but due to the large refrigerant circulation amount, the pressure loss in the liquid pipe is large, and in the same pipe path, the pressure loss is R404A and R404A. , R507 is about 2
The saturation temperature drop of the liquid due to the pressure loss is about 1.7 times for R404A and about 1.8 times for R507 compared to R22.

From these things, R404A and R507
Can be said to be a refrigerant in which flash gas is likely to be generated in the liquid pipe because it is difficult to obtain the degree of supercooling and the degree of saturation temperature drop in the liquid pipe is large. This is because the evaporation temperature is relatively high. Noticeable in the area. It is essential to prevent the generation of flash gas in the refrigeration system.For that reason, not only to reduce the pressure loss in the liquid pipe, but also to further cool the refrigerant liquid condensed in the condenser to obtain the required liquid excess. It is important to obtain the degree of cooling.

In the air-cooled refrigeration system, there are methods such as adding an air-cooled liquid cooler to the air-cooled condenser, but there are R404A and R5.
In No. 07, since the degree of supercooling of the liquid is difficult to obtain, the degree of supercooling of the liquid at the condenser outlet is small, and it is almost zero depending on the operating conditions. Therefore, when the liquid at the condenser outlet is sent to the liquid cooler,
Even if the amount is a small amount in the liquid, bubbles are mixed, and bubbles are generated due to a slight pressure loss, and liquid supercooling is hindered. If the liquid at the condenser outlet is temporarily stored in the receiver tank and sent to the liquid cooler, even if it is possible to prevent bubbles from mixing in the liquid, the piping path is long and
In addition to the drawback of being complicated, not only the pressure loss increases, but also bubbles are generated and the liquid subcooling is hindered.

In addition, in summer, the ambient air temperature is high, the temperature difference with the refrigerant liquid is small, the outer surface of the fin material is dirty, and direct sunlight may be exposed depending on the installation location. It is considered that the desired degree of liquid subcooling cannot be obtained, and it is necessary to reliably obtain the required degree of liquid supercooling regardless of these factors.

[0014]

Cooling the refrigerant liquid with ambient air in order to obtain the desired degree of supercooling of the refrigerant liquid has various factors that reduce the efficiency of heat exchange between the two.

Therefore, in the present invention, as a reliable alternative method, a bypass circuit is provided in the refrigerant liquid pipe to decompress a part of the high-pressure refrigerant liquid out of the total refrigerant circulation amount to evaporate it, and the latent heat of vaporization causes the refrigerant The liquid is cooled, or the refrigerant liquid is cooled by a low-temperature compressor suction gas, and a liquid cooler is provided for cooling the refrigerant liquid.

The liquid cooler is of a double pipe type or a liquid cooler which also serves as a receiver tank by providing a pipe under the receiver tank.

The double pipe type cools the refrigerant liquid by passing the refrigerant or low-temperature compressor suction gas circulating through the bypass circuit on one side and the refrigerant liquid on the other side.

The one that also serves as a receiver tank is configured such that the refrigerant circulating in the bypass circuit or the low-temperature compressor suction gas is passed through the pipe provided in the lower portion of the receiver tank, and the refrigerant liquid retained in the lower portion of the receiver tank is discharged. Cooling.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION According to the method of providing a liquid bypass circuit, a part of high-pressure refrigerant liquid flowing out from a receiver tank normally provided in a refrigerating device is fed into the liquid bypass circuit and is brought to a predetermined pressure. After depressurizing, the liquid is evaporated in the liquid cooler, and the amount of heat corresponding to this evaporation latent heat is exchanged as heat from the medium-temperature refrigerant liquid as sensible heat, making it difficult to achieve liquid subcooling. Get the degree of supercooling.

The refrigerant circulating in the liquid bypass circuit is evaporated in the liquid cooler and then taken into the compressor together with the refrigerant gas at the outlet of the evaporator to circulate in the refrigeration cycle. Further, the liquid cooling according to the present invention is generally required when the evaporation temperature is -1.
Since it is in the evaporation temperature region of 5 ° C. or higher, this is detected by a temperature switch, a pressure switch or the like, and the solenoid valve provided in the liquid bypass circuit is opened / closed for control.

In the method utilizing the low temperature compressor suction gas, the low temperature compressor suction gas is fed into the liquid cooler and exchanges heat with the medium temperature refrigerant liquid to make it difficult to obtain the degree of liquid subcooling.
The desired degree of liquid supercooling is obtained with A and R507.

At this time, the compressor suction gas is overheated,
If the suction gas is not completely dry, this can be eliminated, and if only the suction gas superheat degree is changed under the same conditions, R404A and R507 have a higher superheat degree and a higher refrigerating capacity. There are also advantages. Regarding the control of the compressor discharge gas temperature, R404A and R507 are
Compared with No. 22, in addition to the characteristic that the compressor discharge gas temperature becomes lower, there is no concern regarding the discharge gas temperature excessive rise by utilizing the conventional liquid injection control.

1 to 4 show a refrigeration cycle system diagram of an embodiment according to the present invention.

In FIG. 1, the liquid cooler 3 also serves as the receiver tank 4, and the refrigerant liquid stays therein. A cooling pipe 7 is provided in the lower part of the liquid cooler 3 and is normally immersed in the refrigerant liquid that has stagnated. When the low-temperature compressor suction gas passes through the cooling pipe 7, it exchanges heat with the liquid retained in the liquid cooler 3 to supercool the liquid.

In FIG. 2, the liquid flowing out from the receiver tank 4 and the low temperature compressor suction gas exchange heat with each other in the liquid cooler 8 to supercool the liquid.

In FIG. 3, the liquid cooler 3 also serves as a receiver tank, and the refrigerant liquid stays in the inside thereof. A cooling pipe 7 is provided in the lower part of the liquid cooler 3 and is normally immersed in the refrigerant liquid that has stagnated.

A part of the refrigerant liquid flowing out from the liquid cooler 3 is
It circulates through the liquid bypass pipe 9, and has a solenoid valve 10 and a pressure reducing device 11.
And evaporates in the cooling pipe 7. The latent heat of vaporization cools the refrigerant liquid in the liquid cooler 3 to supercool the liquid.

In FIG. 4, a part of the refrigerant liquid flowing out from the receiver tank 4 circulates in the liquid bypass pipe 9, passes through the solenoid valve 10 and the pressure reducing device 11, and is evaporated in the liquid cooler 8 to be evaporated. The latent liquid cools the refrigerant liquid and supercools the liquid.
In FIGS. 3 and 4, the pressure switch 12 or the temperature switch 13 provided at the outlet of the evaporator 6 detects the pressure or temperature of the gas at the outlet of the evaporator, and the region where the evaporation temperature is approximately −15 ° C. or higher. The electromagnetic valve 10 is opened with and the electromagnetic valve 10 is closed in the evaporation temperature region below that.

[0029]

EFFECTS OF THE INVENTION According to the present invention, the required degree of supercooling of the refrigerant liquid can be stably and surely taken, so that the flash gas in the liquid pipe in the evaporation temperature range of approximately -15 ° C or higher. It is possible to solve the problems such as occurrence of the above and obtain a stable operating state. Regarding the refrigerating capacity and the coefficient of performance, in the theoretical refrigeration cycle, the condensation temperature was 45 ° C and the evaporation temperature was -5.
℃, compressor suction gas temperature 0 ℃, liquid subcooling degree 0deg, liquid bypass method by the liquid subcooling degree 3
When deg is set, the liquid bypass amount is 6% of the total refrigerant circulation amount.
Therefore, both the refrigerating capacity and the coefficient of performance are 9 for the case without liquid bypass.
It will be 9.7%. On the other hand, under the same conditions, when the compressor suction gas is used, the refrigerating capacity and the coefficient of performance are 103% and 102%, respectively, compared with the case where the compressor suction gas is not used,
Not only can the operating conditions be stabilized, but the refrigeration capacity and coefficient of performance can also be improved.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle system diagram in the case where a refrigerant liquid is supercooled by using a compressor suction gas and a liquid cooler also serves as a receiver tank.

FIG. 2 is a system diagram when a liquid cooler is provided separately from the receiver tank of FIG.

FIG. 3 is a refrigeration cycle system diagram in the case where a part of the liquid refrigerant is bypassed to be evaporated and the latent heat of evaporation is used to supercool the refrigerant liquid, and the liquid cooler also serves as a receiver tank.

FIG. 4 is a system diagram when a liquid cooler is provided separately from the receiver tank of FIG.

[Explanation of symbols]

1 ... Compressor, 2 ... Condenser, 3, 8 ... Liquid cooler, 4 ... Receiver tank, 5 ... Expansion valve, 6 ... Evaporator, 7 ... Cooling pipe,
9, 10 ... Solenoid valve, 11 ... Pressure reducing device, 12 ... Pressure switch, 13 ... Temperature switch, 14 ... Accumulator.

Claims (1)

[Claims] 1. A refrigeration apparatus using HFC-based R404A and R507 as a refrigerant, by appropriately supercooling a liquid refrigerant to prevent flash gas generation in a liquid pipe and to suppress deterioration of refrigerating capacity. A liquid cooler for a refrigerating apparatus, comprising a liquid cooler for maintaining a stable operating state.