JPH0419460B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention allows a refrigerant liquid to flow down along the inner wall of a vacuum heat transfer tube installed vertically, and exchanges heat with the outside of the machine via the heat transfer tube. The present invention relates to an evaporator for an absorption chiller that obtains cold air for cooling, hot water for heating, hot air, or hot water by doing so.

(b) Prior art Absorption refrigeration cycles that obtain cooled fluid or heated fluid through a closed circulation cycle of refrigerant and absorbent include absorption refrigerators, absorption chiller/heaters, and absorption heat pumps (all of which collectively produce absorption cold and heat). There is a machine). In order to re-separate the refrigerant from the absorption liquid that has absorbed the refrigerant, both of these absorption chillers include a generator that heats the absorption liquid, and an evaporator that cools the refrigerant gas obtained by this generator, condenses it, and liquefies it. It has a condenser that sends the refrigerant to the generator, and an absorber that absorbs the refrigerant vaporized in the evaporator and returns it to the generator.

There are two types of evaporators in such absorption coolers: vertical evaporators with heat transfer tubes arranged vertically, and horizontal evaporators with horizontal evaporators. The vessel is provided with a liquid reservoir header at the top, and a method is adopted in which each heat transfer tube has a method in which liquid refrigerant is introduced to the inner wall of the tube by overflowing from a notch provided at the tip of each tube. However, such overflow from the notch has the drawback that the amount of refrigerant flowing into each heat transfer tube varies greatly depending on the levelness of the liquid reservoir header and the direction of the notch.

In order to eliminate this drawback, a method is also used in which a nozzle is installed at the top of the heat exchanger tube and the refrigerant liquid is sprayed under pressure with a pump to guide it into the heat exchanger tube and form a liquid film. In an absorption chiller that maintains a cooling function by keeping the inside of the machine in a vacuum, it is preferable to provide the same function without using a pump or the like, which is likely to reduce airtightness.

(c) Purpose of the Invention This invention, which was made in view of the above points, has a specially constructed liquid disperser inserted into the upper part of each heat exchanger tube, and the heat exchanger tube can be heated without using a special pressurizing device such as a pump. This makes it possible to uniformly wet the inner surface of the container.

(d) Structure of the Invention The evaporator of the absorption chiller according to the present invention includes a heat transfer tube that is installed vertically and has a large number of heat exchange fins on the outside, and a liquid disperser that is inserted into the upper part of the heat transfer tube. The liquid distributor forms a liquid reservoir above the inside of the heat exchanger tube, and has a column below the liquid reservoir that communicates with the liquid reservoir and forms a liquid supply gap along the inner wall of the heat exchanger tube. to form a falling thin film of refrigerant liquid on the inner wall of the heat transfer tube, while an overflow hole is provided in the upper part of the column for allowing the refrigerant liquid overflowing from the liquid reservoir to flow down to the lower inner wall of the heat transfer tube; A passageway is formed to ensure stable operation of the absorption chiller.

(e) Examples Examples of the present invention will be described below with reference to the drawings. In Example 1, for example, 2-2-2 trifluoroethanol (hereinafter referred to as TFE) is used as a refrigerant, and TFE is heated and vaporized from an absorbent. 2 is a condenser that cools and liquefies gaseous TFE and supplies it to evaporator 3; 4 is a generator that vaporizes gaseous TFE in evaporator 3;
This is an absorber that absorbs TFE refrigerant gas with an absorbent and returns it to the generator 1, and these vessels include refrigerant pipes 5,
They are connected by absorption liquid pipes 6 and 6' to form an absorption refrigeration cycle in which the inside of the vessel is evacuated.

The evaporator 3 has a disperser 8 above which once receives the refrigerant liquid flowing from the condenser 2 and causes it to flow down to the heat transfer tubes 7, and the disperser 8 has a flash chamber 9 therein.
It has a refrigerant receiver 10 connected to the flash chamber 9, a tray 11 for refrigerant distribution, a dispersion plate 12, etc., and the liquid is separated almost evenly by the siphon 13 of the tray 11 and dripped onto the dispersion plate 12. The refrigerant liquid is supplied to the liquid distributor 14 above the heat transfer tube 7.

The liquid disperser 14 consists of an overflow part 15 that is narrower than the inner diameter of the heat exchanger tube 7 and a column 17 that is in contact with the inner wall 16 of the heat exchanger tube. A refrigerant liquid reservoir 20 is formed here and also serves as the bottom of the space. Also, column 17
The side wall of the heat exchanger tube has a large number of helical grooves 21 formed inside the heat exchanger tube 7 in contact with the inner wall 16 of the heat exchanger tube, and a liquid supply gap is formed at the lower part of the refrigerant liquid reservoir 20 along the inner wall of the heat exchanger tube. I try to do that. The overflow part 15 has a rod 22 protruding into the liquid pool 20.
A horizontal hole 23 is provided near the top of the head,
When the amount of liquid in the refrigerant liquid reservoir 20 increases, this horizontal hole 2
The refrigerant liquid flowing in from the heat exchanger tube 7 is caused to flow down through the passage 24 and the conical diffusion wall 25 at the bottom of the column.

In addition, 26 is a heat exchange fin wound around the outer wall of the heat exchanger tube 7, and in the figure, a thin strip-shaped aluminum needle-like fin is wound.

The evaporator of the present invention having such a configuration adjusts the flow rate of the refrigerant in the liquid supply gap formed between the columnar body 14 and the inner wall 16 of the heat exchanger tube, and distributes the refrigerant liquid along the inner surface of the heat exchanger tube. In this case, the amount of flow is adjusted, that is, the size of the liquid supply gap is controlled by the dispersion plate 1.
The size of the refrigerant liquid dripping from 2 is adjusted so that it accumulates in a liquid reservoir, so that even if the amount of refrigerant dripping changes, the amount of wetting inside the pipe does not change greatly. The overflow hole 23 also prevents the liquid level of the liquid reservoir from rising abnormally when the amount of refrigerant changes, and the liquid refrigerant flowing out from the overflow hole 23 also flows through the diffusion wall 25. It is configured to flow down along the inner wall 16 of the heat exchanger tube 7.

It should be noted that most of the refrigerant flowing down the inner wall of the heat transfer tube 7 in this way is heated by the heat transmitted from the outside of the heat transfer tube, vaporizes, becomes gaseous refrigerant gas, and flows through the lower header 27. It flows into the absorber 4 and is absorbed by the absorption liquid.

In addition, when using a tube without a helical groove on the inner surface as a heat transfer tube, a thin groove is formed on the outer surface of the column 14 of the liquid distributor, and such a column is press-fitted into the heat transfer tube to connect it with the inner wall of the tube. A liquid supply gap may be formed between the column and the column. The dimension letters in FIG. 2 and FIG. 4 are a cross-sectional view of a column and a heat exchanger tube showing a specific example of the evaporator of the present invention.

Inner diameter of heat exchanger tube d = 9.2mm, width of helical groove W = 0.4
mm, also for a heat exchanger tube with angle β = 25 degrees and depth h = 0.15 mm, outer diameter D = over 9.2 mm, length l = 10 mm, height to overflow port H = 7 mm, apex angle α of the cone As a result of experiments using TFE as a refrigerant and press-fitting a column with a temperature of 120 degrees, it was confirmed that the refrigerant has good wetting characteristics and can be used as an efficient evaporator.

(F) Effects of the Invention This invention involves inserting a column into a heat transfer tube that cooperates with the wall of the heat transfer tube to form a liquid pool at the top of the heat transfer tube, and at the same time inserting a column into the heat transfer tube and inserting the column into the inner wall of the heat transfer tube. This is an evaporator in which a liquid supply gap is formed between the liquid supply gap and the refrigerant liquid in the liquid reservoir flows down along the inner wall of the heat transfer tube through this liquid supply gap, so it is different from conventional evaporators of this type. Compared to the evaporator, the inner wall of each heat transfer tube that makes up the evaporator can be uniformly wetted with refrigerant liquid over the entire circumference, and the refrigerant can be vaporized by effectively utilizing all the heat transfer surfaces of the heat transfer tube. This prevents the dripping of unevaporated liquid refrigerant and the resulting drop in efficiency of the absorption chiller.

In addition, since the amount of flowing liquid in a liquid disperser is not determined by a notch like in the conventional case, the influence of deviations in the horizontality of the tray and the verticality of the heat transfer tube is smaller than in the conventional case, and the performance is stable. This makes it possible to provide a vertical evaporator for an absorption chiller.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an evaporator and a liquid disperser of an absorption cooler according to the present invention, FIG. 2 is an enlarged longitudinal sectional view of a heat transfer tube, and FIG.
FIG. 4 is an enlarged sectional view showing an example of a heat exchanger tube. 3... Evaporator, 7... Heat exchanger tube, 8... Liquid disperser, 14... Column, 23... Overflow hole, 24... Passage.

Claims (1)

[Claims] 1. In an evaporator in which a liquid disperser is provided at the top of a vertically installed heat transfer tube, and the refrigerant liquid flowing down the tube is heated and vaporized by the heat transmitted from the outside of the tube. The liquid distributor cooperates with the heat exchanger tube wall to form a liquid reservoir at the upper part of the heat exchanger tube, and the lower part of this liquid reservoir communicates with the liquid reservoir to form a liquid supply gap along the inner wall of the heat exchanger tube. The absorption absorber is characterized in that the columnar body is provided with an overflow hole through which the refrigerant liquid overflowing from the liquid reservoir flows down to the inner wall of the heat transfer tube through a passage provided in the columnar body. Evaporator of chiller.