JP3301808B2 - Absorption refrigerator regenerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerator for an absorption refrigerator for evaporating and separating a refrigerant, and more particularly to a regenerator using a relatively low temperature fluid as a heat source.

[0002]

2. Description of the Related Art In this type of regenerator, a heat transfer tube through which a heat source fluid flows is disposed at a portion where an absorbing liquid is stored.
The heat of the heat source fluid is transferred to the absorbing liquid that is in contact with it via the heat transfer tube and heated, and the refrigerant absorbed in the absorbing liquid is evaporated to separate and generate. The surface of the heat transfer tube (liquid contact surface) The heat transfer area is increased by providing fins and irregularities on the
There is a technology that improves heat transfer performance and saves energy consumption.

[0003] However, if the surface of the heat transfer tube is a special heat transfer surface (for example, an uneven surface), the fluid surrounded by the heat transfer surface has a reduced fluidity and is overheated locally. become.
However, since the heat transfer surface mechanically processed into fins is unlikely to become a boiling nucleus, there is a problem that the boiling does not start in spite of the increase in the degree of superheat, and the regeneration efficiency does not increase as expected.

On the other hand, with the effective use of energy or the spread of cogeneration systems, there is a momentum to actively utilize low-temperature exhaust heat from factory plants.

[0005]

However, in the conventional regenerator, even if low-temperature exhaust heat is used as a heat source for separating the refrigerant vapor from the absorbing liquid, the effect as expected is expected because the temperature difference is too small. Difficult to raise and therefore
The development of a regenerator capable of efficiently regenerating a refrigerant using a relatively low-temperature fluid such as low-temperature exhaust heat as a heat source has been expected.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is directed to a regenerator for an absorption refrigerator which evaporates and separates a refrigerant using a relatively low temperature fluid as a heat source. A regenerator for an absorption refrigerator in which a porous plate is provided in close proximity to a heat transfer tube through which a heat source fluid flows, wherein the porous plate is close to above the heat transfer tube through which the heat source fluid flows. A regenerator for an absorption refrigerator, wherein the regenerator is provided with a porous plate disposed close to a periphery of a heat transfer tube through which a heat source fluid flows. It is.

[0007]

The flow of the absorbing liquid between the heat transfer tube and the porous plate is hindered by, for example, unevenness of the liquid contacting heat transfer surface. Therefore, by arranging the porous plate close to the liquid-contacting heat transfer surface, foaming is promoted by the easily boiling cavity existing in the porous material provided in the superheated liquid layer, and the heat transfer characteristics are improved. In addition, the steam bubbles that have foamed from the surface of the heat transfer tube do not leave the heat transfer surface immediately, but flow while being held between the heat transfer tube and the porous plate. , Good heat transfer performance is obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a regenerator 1 according to a first embodiment will be described with reference to FIGS. In the figure, 11 is an inlet of the absorbing liquid, 12 is an outlet of the absorbing liquid, 13 is a heat transfer tube for heating the absorbing liquid, which is horizontally installed in a plurality of stages at the bottom of the inside and through which a low-temperature fluid flows, and 13A is these heat transfer tubes 13 heat transfer tube groups,
Reference numeral 14 denotes a sponge-like metal plate provided above the upper heat transfer tube. The distance between the upper heat transfer tube 13 and the spongy metal plate 14 is preferably about 0.01 to 5 mm. Reference numeral 15 denotes a low-temperature fluid inlet-side cover, and 16 denotes an outlet-side cover.

The spongy metal plate 14 is made of a material excellent in heat resistance and corrosion resistance, for example, Ni, Ni—Cr alloy, Ni—C
An r-Al alloy or the like is formed in a three-dimensional network like a sponge. Generally, the holes forming the network have a diameter of about 100 μm to several mm and a porosity of about 85% or more. Is preferred.

When expressed in terms of the number of holes, it is possible to use from about 6 to 11 holes / inch to about 50 to 70 holes / inch, and particularly preferred is from about 11 to 17 holes / inch to 26 to 35 holes / inch. It is of the order of inches. Further, when viewed in terms of the specific surface area, it is about 500 to 7500 m ² / m ³ , which is about 1.3 to
20 times. Therefore, when the spongy metal plate 14 is installed close to the heat transfer tube 13, the specific surface area is significantly increased, and the heat transfer performance is further improved.

For example, FIG. 2 shows a stainless steel having a smooth finished surface and a hole diameter of approximately 1.5 to 2.
A spongy metal plate 14 having a thickness of 3 mm, a number of holes of about 11 to 17 holes / inch, a specific surface area of about 1000 m ² / m ³ , and a thickness of 3 mm.
Is a pool boiling experiment result of an aqueous solution of lithium bromide, which was installed with a distance of 0.1 mm.

From the above experimental results, in the case of only smooth stainless steel, for example, when the heat flux is q = 10 ⁵ W / m ² , the superheat degree ΔT is 20 ° C. When the plate 14 is mounted, the same heat flux q = 10 ⁵
Since the degree of superheat ΔT at W / m ² is 12 ° C., it can be seen that the temperature of the heat transfer surface has decreased by 8 ° C. (heat transfer performance has been improved). At this time, the boiling heat transfer coefficient is 20/12 ≒
It can be seen that the improvement is 1.67 times.

The improvement of the heat transfer performance is particularly remarkable in the case of a low heat flux. For example, when the heat flux q is 10 ⁴ W / m ² , the degree of superheat ΔT is 9.5 ° C. depending on the presence or absence of the spongy metal plate 14.
And 4 ° C, the heat transfer performance is 9.5 / 4 ／
An improvement of 2.4 is seen.

The regenerator 1 having the above configuration is used, for example, as a regenerator 1 for an absorption refrigerator having the configuration shown in FIG. In the regenerator 1 of this refrigerator, an absorbent (dilute) having a reduced concentration by absorbing the refrigerant in the absorber 2 is supplied to the absorbent pump P1.
, And a relatively low-temperature fluid, that is, warm wastewater from a factory plant, can be appropriately introduced into the heat transfer tube 13 by operating a valve. Therefore, inside the regenerator 1, the absorbing liquid and a low-temperature fluid such as warm wastewater exchange heat via the heat transfer tube 13, and the absorbing liquid is heated to evaporate and separate the refrigerant. It is discharged toward the solution heat exchanger 5 and the absorber 2.

At this time, in the regenerator 1 of the present invention, since the spongy metal plate 14 is provided close to the heat transfer tube 13, the absorbing liquid heated on the surface of the heat transfer tube hardly flows, so that it is easily overheated. As a result, boiling occurs not only on the surface of the heat transfer tube but also on the liquid contact surface of the sponge-like metal plate 14 that gives additional nucleate boiling, so that the boiling is promoted. Since it is held between the metal plate 14 and the surroundings, the surrounding superheated liquid layer is induced to evaporate and an environment in which the evaporator is easily evaporated is formed, and the heat transfer performance as a whole is significantly improved.

That is, since the subcooled liquid having a temperature lower than the saturation temperature flows on the surface of the conventional heat transfer tube, it condenses and disappears even if micro bubbles are generated. When 14 is installed close to the heat transfer tube 13,
Saturated boiling easily occurs.

As described above, in the regenerator 1 of the present invention, by arranging the spongy metal plate 14 close to the heat transfer tube 13, it is possible to optimize the heat and fluid environment near the heat transfer surface. is there. For this reason, there is a strong tendency that bubbling of the refrigerant is usually difficult in a place where the absorbing liquid is deep, but also in this part, in the regenerator 1 of the present invention, the spongy metal plate 1 is close to the heat transfer tube 13.
4 is provided, it is easy to generate refrigerant vapor.

Further, since the heat transfer surface of the heat transfer tube 13 is not processed, it is easy to manufacture, and there is no fear of corrosion of the heat transfer surface. In addition, since the heat transfer performance is significantly improved, there is an advantage that the entire regenerator can be reduced in size.

In FIG. 3, reference numeral 3 denotes a condenser for condensing and cooling the refrigerant flowing from the regenerator 1 by the cooler 31, and reference numeral 4 denotes a latent heat when the refrigerant liquid from the condenser 3 is sprayed and evaporated. An evaporator P2 is used to obtain cooling water for cooling from the water cooler 41, and a refrigerant pump P2 is connected to each other to form a refrigeration cycle.

FIG. 4 shows the structure of a regenerator 1A according to another embodiment. In this embodiment, a spongy metal plate 14 surrounds the upper part, one side and lower part of the heat transfer tube group 13A. It is installed in a U-shape. Spongy metal plate 1
By installing 4 in this manner, the foamed steam surrounds the heat transfer tube, which increases the temperature of the absorbing solution,
Since boiling is promoted, there is an advantage that boiling performance is further improved.

The regenerator 1.1A having the above configuration can also be used as the low temperature regenerator 1 of the double effect absorption refrigerator having the configuration shown in FIG. In the figure, reference numeral 7 denotes a high-temperature regenerator having a heating means such as a burner for heating the rare liquid sent from the absorber 2 by the absorbing liquid pump P1 to evaporate and separate the refrigerant. In this case, the separated refrigerant vapor flows into the heat transfer tube 13 as a heat source of the regenerator 1. Reference numeral 6 denotes another solution heat exchanger for exchanging heat between the dilute solution coming out of the absorber 2 and going to the high temperature regenerator 7 and the intermediate solution coming out of the high temperature regenerator 7 and going to the regenerator 1.

As described above, even when the absorbing liquid is heated by the refrigerant vapor, since the sponge-like metal plate 14 is disposed close to the upper side of the heat transfer tube 13, foaming occurs from the superheated liquid layer near the heat transfer tube 13. By maintaining the easily generated and foamed vapor in the vicinity of the heat transfer tube 13, the temperature boundary layer is disturbed, and high heat transfer performance can be achieved.

Since the present invention is not limited to the above embodiment, it goes without saying that the general structure and shape of the regenerator and the materials used can be appropriately changed.

Further, instead of the spongy metal plate 14, a porous metal plate in which a part of the gap is confined in a bubble-like shape may be provided, or a wire mesh metal plate may be provided. Is also possible.

Further, even if four porous metal plates 17 are provided around the heat transfer tube group 13A as shown in FIG. 6, a plurality of porous metal plates 17 are provided vertically between the heat transfer tubes 13 as shown in FIG. Alternatively, a plurality of heat transfer tubes 13 may be provided laterally between the heat transfer tubes 13 as shown in FIG. 8, or may be provided above and beside the heat transfer tube group 13A as shown in FIG.

[0026]

As described above, according to the regenerator according to the present invention, the flow of the absorbing liquid between the heat transfer tube and the porous plate is hindered. Therefore, foaming is promoted by the easily boiling cavity of the porous plate provided in the superheated liquid layer, and heat transfer characteristics are improved. In addition, steam bubbles that have foamed from the heat transfer tube surface do not immediately leave the heat transfer surface,
Since it flows while being held between the heat transfer tube and the porous plate, the temperature boundary layer is disturbed, and a high heat transfer coefficient is obtained.
Not only can the regenerator be reduced in size, but also a remarkable effect can be obtained, for example, it is possible to effectively use low-temperature exhaust heat from a factory plant as a heating source.

[Brief description of the drawings]

The drawings show embodiments of the present invention, and the contents of each drawing are as follows.

FIG. 1 is an explanatory diagram of one embodiment.

FIG. 2 is a boiling curve of a smooth surface.

FIG. 3 is an explanatory diagram of one usage example.

FIG. 4 is an explanatory diagram of another embodiment.

FIG. 5 is an explanatory diagram of another usage example.

FIG. 6 is an explanatory diagram of an arrangement relationship between a heat transfer tube and a porous plate.

FIG. 7 is an explanatory diagram of an arrangement relationship between another heat transfer tube and a porous plate.

FIG. 8 is an explanatory diagram of an arrangement relationship between another heat transfer tube and a porous plate.

FIG. 9 is an explanatory diagram of an arrangement relationship between another heat transfer tube and a porous plate.

[Explanation of symbols]

 1.1A regenerator 11 inlet 12 outlet 13 heat transfer tube 13A heat transfer tube group 14 spongy metal plate 17 porous plate 2 absorber 3 condenser 4 evaporator 5.6 solution heat exchanger 7 high temperature regenerator P1 absorption liquid pump P2 Refrigerant pump

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 33/00

Claims (3)

(57) [Claims] 1. A regenerator for an absorption refrigerator that evaporates and separates a refrigerant using a relatively low temperature fluid as a heat source, wherein a porous plate is provided near a heat transfer tube through which the heat source fluid flows. Absorption refrigerator regenerator. 2. A regenerator for an absorption refrigerator for evaporating and separating a refrigerant using a relatively low-temperature fluid as a heat source, wherein a porous plate is installed close to and above a heat transfer tube through which a heat source fluid flows. A regenerator for absorption refrigerators. 3. A regenerator for an absorption refrigerator for evaporating and separating a refrigerant using a relatively low-temperature fluid as a heat source, wherein a porous plate is installed near a heat transfer tube through which a heat source fluid flows. A regenerator for absorption refrigerators.