JPH06272998A - Refrigerator - Google Patents

Abstract

PURPOSE:To suppress a large temperature change due to non-azeotropic mixture refrigerant and to improve a refrigerating capacity by forming an evaporator of a tube for feeding the refrigerant and cooling fins, and so forming a sectional area of a refrigerant flow rate flowing in the tube as to be sequentially reduced along a flowing direction of the refrigerant. CONSTITUTION:An evaporator 9 is formed of a tube 15 connected to a refrigerating tube and fins 17. The tube 15 is so set that a sectional area of refrigerant flow rate is sequentially reduced from an inlet side 15a to an outlet side 15b. Since a flowing velocity of the refrigerant flowing in the tube 15 is sequentially accelerated toward the outlet side 15b in the evaporator 9, a heat exchanging amount is increased. On the other hand, as a pressure loss is increased, a temperature gradient at the time of phase change of mixed refrigerant and an evaporating temperature are held substantially the same, and a temperature difference of inlet and outlet sides of the evaporator 9 can be suppressed to a small value. Accordingly, frosting, icing do not occur, and an efficient refrigerating can be conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system using a non-azeotropic mixed refrigerant as a refrigerant.

[0002]

2. Description of the Related Art Generally, in a refrigeration system, for example,
As shown in FIG. 6, it comprises a compressor 101, a condenser 103, a decompression device 105, and an evaporator 107.

During the cooling operation, the refrigerant flows from the compressor 101
Passing through the condenser 103, the pressure reducing device 105, and the evaporator 107,
The refrigerant that has finished its work returns to the compressor 101 again and repeats the refrigeration cycle.

[0004]

As described above, in the refrigerating apparatus, the refrigerating mode can be obtained by repeating the refrigerating cycle of the refrigerant. In this case, R2 becomes a single refrigerant
For example, when a non-azeotropic mixed refrigerant composed of R32 and R134a is used as the alternative refrigerant of No. 2, when the liquid is evaporated at a constant pressure as shown in FIG. 7, the liquid refrigerant follows the evaporation accompanying the gas-liquid phase change. The composition of the above changes, and the evaporation temperature between the inlet side and the outlet side, that is, the temperature gradient greatly rises accordingly.

This temperature difference (T2-T1) changes depending on conditions such as the composition and mixing ratio of the refrigerant, but for example, it becomes a negative temperature on the inlet side of the evaporator and a positive temperature on the outlet side.
In some cases, frost may occur near the inlet of the evaporator,
There is a problem that the performance is significantly deteriorated due to the influence of a large temperature change, such as the possibility of freezing.

Therefore, it is an object of the present invention to provide a refrigerating apparatus capable of improving a refrigerating capacity by suppressing a large temperature change due to a non-azeotropic mixed refrigerant.

[0007]

In order to achieve the above object, the present invention relates to a refrigerating apparatus using a non-azeotropic mixed refrigerant in a refrigerant circuit composed of a compressor, a condenser, a pressure reducing device and an evaporator. In the above, the evaporator is formed of a tube through which a refrigerant flows and fins for cooling, and has a shape in which the cross-sectional area of the flow rate of the refrigerant flowing through the tube is gradually reduced along the flow direction of the refrigerant.

[0008]

In this refrigeration system, when the cooling operation is started,
The compressor inhales and compresses the refrigerant gas to generate high temperature and high pressure, and sends it out. This hot high pressure gas enters the condenser. At this time, the refrigerant gas is liquefied by depriving the latent heat of condensation by the air passing through the fins.

The liquefied refrigerant flows to the decompression device, where the high-pressure refrigerant rapidly expands and becomes a low-temperature low-pressure mist.
The atomized refrigerant flows to the evaporator, where the air passing through the fins deprives the latent heat of vaporization and changes from atomized to gaseous,
It flows to the compressor again. Freezing is performed by repeating this refrigeration cycle.

In the evaporator during this refrigeration cycle, the cross-sectional area that gradually decreases from the inlet side to the outlet side
Since the flow velocity of the refrigerant becomes faster, the heat exchange amount increases. On the other hand, since the pressure loss increases due to the influence of the cross-sectional area, the temperature gradient and the evaporation temperature during the phase change of the mixed refrigerant can be kept substantially constant. Therefore, since the temperature change can be suppressed to a small level, problems such as freezing do not occur and the refrigerating capacity is improved.

[0011]

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

FIG. 2 shows a refrigerating apparatus in which a non-azeotropic mixed refrigerant is enclosed, wherein 1 is a compressor having a suction cup 3, 5 is a condenser, 7 is a decompressor, and 9 is an evaporator. And is connected and communicated via the refrigerant pipe 11 to form a refrigeration cycle.

The compressor 1 functions to discharge the gaseous non-azeotropic refrigerant from the suction cup 3 as a high temperature, high pressure refrigerant gas.

The condenser 5 is composed of tubes and fins (neither of which is shown) connected to the refrigerant pipe 11, and the refrigerant gas fed from the compressor 1 in the form of high temperature and high pressure gas is fed by the fan 13. The air passing through the fins deprives the latent heat of condensation into a mist.

The decompression device 7 functions to atomize the refrigerant at a low temperature and a low pressure and to make the refrigerant flow rate corresponding to an operating condition such as a heat load according to a command signal from a refrigerant temperature detecting portion (not shown). .

The evaporator 9 is composed of tubes 15 and fins 17 connected to the refrigerant pipe 11, and the refrigerant passing through the tubes 15 in the evaporator 9 gives latent heat of evaporation to the air passing through the fins 17 by the fan 14. It will be deprived of gas.

As shown in FIG. 1, the tube 15 of the evaporator 9 is set so that the cross-sectional area of the flow rate of the refrigerant gradually decreases from the inlet side 15a to the outlet side 15b.

With respect to the inner diameter of the tube 15, the refrigerant flow velocity increases from the inlet side 15a to the outlet side 15b, while the pressure loss is gradually increased as shown in FIG.
Of the inlet side 1 so that the evaporation temperature of is almost the same as the temperature gradient b.
The cross-sectional area of 5a is large, and the inner diameter becomes smaller toward the outlet side 15b.

In this case, as shown in FIG. 3, the tubes 15 formed in the same cross-sectional area are sequentially reduced from the inlet side 15a to the outlet side 15b so that the number of passes is three, two, and one. It is also possible to make it into a tube shape.

According to such a refrigerating apparatus, the refrigerant gas is sucked and compressed by the compressor 1 and is sent out at high temperature and high pressure. This high-temperature high-pressure gas enters the condenser 5. At this time, the refrigerant gas is liquefied by depriving the latent heat of condensation by the air passing through the fins.

The liquefied refrigerant flows to the decompression device 7, where the refrigerant rapidly expands into a low-temperature, low-pressure mist. Next, after flowing into the evaporator 9 and the air passing through the fins 17 deprives the latent heat of evaporation into a mist form and becomes a gas form, the compressor 1 is again formed.
The refrigerating cycle that flows through is repeated.

In the evaporator 9 during this refrigeration cycle,
Since the flow velocity of the refrigerant flowing through the tube 15 gradually increases toward the outlet side 15b, the heat exchange amount increases. On the other hand, as the pressure loss increases, in the evaporation step a, the temperature gradient and the evaporation temperature during the phase change of the mixed refrigerant are kept substantially the same, and the temperature difference between the inlet side and the outlet side of the evaporator 9 can be suppressed to be small. .

Therefore, frosting and freezing do not occur, and efficient freezing operation can be performed.

In this case, as shown in FIG. 5, the tube 1
The same effect can be expected by providing the heat transfer promoting means 19 in which the pressure loss gradually increases along the flow direction of the refrigerant.

That is, the resistor 21 serving as the heat transfer promoting means 19 is provided inside the tube 15 having the same inner diameter.

The resistance bodies 21 project toward the center, and the number of resistance bodies 21 is set to be small on the inlet side 15a and gradually increase on the outlet side 15b so that the pressure loss gradually increases toward the outlet side. ing.

Therefore, the resistance area of the refrigerant flowing in the tube 15 is greatly expanded by the resistor 21, and the heat exchange amount is increased. Further, as shown in FIG. 4, the temperature gradient b and the evaporation temperature a during the phase change of the mixed refrigerant are kept substantially the same,
Since the temperature difference between the inlet side and the outlet side of the evaporator 9 can be suppressed to be small, frosting and freezing do not occur, and efficient refrigerant operation can be performed.

Although the refrigerating apparatus has been described in this embodiment, it may be applied to an air conditioner dedicated to cooling.

[0029]

As described above, according to the refrigerating apparatus of the present invention using the non-azeotropic mixed refrigerant, the evaporation temperature of the evaporator can be brought close to the temperature gradient at the phase change of the mixed refrigerant. As a result of eliminating the large temperature difference between the inlet side and the outlet side, frost and freezing due to the temperature difference do not occur, and moreover, the flow rate of the refrigerant increases and the heat exchange amount increases, so that the refrigerating capacity can be improved. become.

[Brief description of drawings]

FIG. 1 is an explanatory view showing tubes and fins of an evaporator.

FIG. 2 is a piping diagram of the entire refrigeration system according to the present invention.

FIG. 3 is an explanatory view similar to FIG. 1, showing a modified example of the tube of the evaporator.

FIG. 4 is a Mollier diagram according to the present invention.

FIG. 5 is an explanatory view similar to FIG. 1, showing a modified example of the tube of the evaporator.

FIG. 6 is a piping diagram similar to FIG. 2 showing a conventional example.

FIG. 7 is a Mollier diagram of a conventional example.

[Explanation of symbols]

 1 Compressor 5 Condenser 7 Decompressor 9 Evaporator 15 Tube 17 Fin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Yamamoto 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Incorporated, Toshiba Living Space Systems Engineering Laboratory (72) Inventor Yoshihiro Ito 8 Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa Banchi Co., Ltd. Toshiba Living Space Systems Engineering Laboratory

Claims (2)

[Claims] 1. A refrigerating apparatus using a non-azeotropic mixed refrigerant in a refrigerant circuit constituted by a compressor, a condenser, a pressure reducing device and an evaporator, wherein the evaporator is provided with tubes through which the refrigerant flows and fins for cooling. And an air conditioner having a shape in which the cross-sectional area of the flow rate of the refrigerant flowing through the tube gradually decreases along the flow direction of the refrigerant. 2. The refrigerating apparatus according to claim 1, wherein the evaporator has a heat transfer promoting means in the tube in which the pressure loss is gradually increased along the flow direction of the refrigerant.