JPS60263096A - Horizontal evaporating tube for heat exchanger - Google Patents

Abstract

PURPOSE:To permit to obtain high heat transfer coefficient by a method wherein a thin tubular body, forming a small gap between the inner wall of the tube and provided with a vapor flowing port and an operating liquid flowing port at the upper and lower parts thereof, is inserted into the tube. CONSTITUTION:The thin cylindrical body 6, having a diameter slightly smaller than the tube 1, forming the small gap 7 between the inner wall of the tube 1 and provided with a continuous slit type vapor flowing port 8 on the upper part in the axial direction thereof, is inserted into the evaporating tube 1 equipped horizontally while the lower parts of both ends of the thin cylindrical body 6 are formed with the operating liquid flowing ports. According to this method, the contact area between the operating liquid on the inner surface of the tube 1 may be increased by the surface tension of the operating liquid 5 and the high heat transfer coefficient may be obtained. In this case, the size of the small gap 7 is the smaller the more effective.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a horizontal evaporation tube of a heat exchanger to which the principle of heat vibration is applied.

[Conventional technology]

A heat vibrator is a device in which a working fluid is sealed in an evacuated sealed tube.
It heats one end to evaporate the working fluid and condenses it at the other end to release heat.It has excellent heat transfer properties and is also known as a transcendental conductor. Applying this principle, a closed circuit is formed by connecting the evaporation tube and the condensation tube with a steam tube and a condensate tube, and the inside is evacuated to remove the working fluid. It is used for various purposes including recovery.The heat transfer rate in the evaporation tube accounts for a large proportion of the amount of heat exchanged in such a heat exchanger, and in particular the tube that involves evaporation has a gas phase and a liquid phase. The heat transfer coefficient in the gas phase is very low, and the evaporator tube is placed vertically to form an annular flow to improve the heat transfer coefficient.

However, since the effective length of the annular flow is short compared to the length of the evaporator tube, the heat transfer coefficient is not very high. Furthermore, if a heat source containing dust such as exhaust gas is used for heating, the dust will accumulate on the outer surface of the evaporation tube, reducing the heat transfer coefficient on the outer surface of the tube. Therefore, it is necessary to remove this, but fins are provided on the outer surface of the tube to expand the heat transfer area.
Dust removal was extremely difficult.

In view of this, the inventors of the present invention have conducted various tests and developed a heat exchanger that is easy to take measures against dust and can obtain a high heat transfer coefficient in the pipes. 45
It was proposed by No. 150. This heat exchanger has an evaporating tube (1) horizontally arranged as shown in Figure 3, and a condensing tube (2).
The evaporator pipe (1) is connected to the steam pipe (3) and the condensate pipe (4), and the inside is evacuated and a working fluid (5) is filled in. This heat exchanger holds the liquid (5).According to this heat exchanger, the evaporation tube (
1) The dust attached to the outer surface can be easily removed by washing with water and/or using a seat cleaning system.

[Problems to be Solved by the Invention] The heat exchanger using horizontal evaporation tubes not only makes it easy to remove dust, but also has a heat transfer coefficient that is almost equal to or higher than that of heat exchange using vertical evaporation tubes. However, the heat transfer coefficient is not that high, and an improvement in heat transfer coefficient is desired.

Means for Solving Problem C] The present inventors (as a result of further studies on this issue) have developed a horizontal evaporation tube that has a high heat transfer coefficient. A thin cylindrical body that is attached to an evaporator tube and that heats and evaporates the internal working fluid from the outside, with a slit formed between the tube and the inner wall, and a vapor flow port at the top and a working fluid flow port at the bottom. It is characterized by the insertion of.

That is, as shown in FIG. 1(a) and ([]), the present invention has a evaporator tube (1) installed horizontally, which has a diameter that is somewhat smaller than that of the chain tube (1) and is connected to the inner wall of the tube (1). Insert a thin cylinder (6) provided with a slit-shaped vapor flow port (8) continuous in the upper axial direction forming a narrow gap (7), and
1s is used as a hydraulic fluid flow port. Furthermore, thin-walled cylindrical body (
Although we have explained the example in which a slit-shaped steam flow port (9) that connects Vci in the upper axial direction of 6) is provided, the explanation is not limited to this.
Instead, for example, a discontinuous slit-like or hole-like vapor flow port may be provided (j, or furthermore, a plurality of holes may be provided in the upper axial direction) to serve as a working fluid flow port. In the case of a short length, the upper parts of both ends of the thin-walled cylinder (1) may be used as steam flow ports, and the upper part may be used as a hydraulic fluid flow port. Set up (we accept petafin).

Also, Figures 2 (a) and (b) show the evaporation tube (1) installed horizontally.
) has a somewhat smaller diameter than the chain pipe (1) (a sulin 1-shaped fish air flow opening (8) that continues in the upper axial direction and forms a slit (7) with the inner wall of the pipe (1)). A plurality of short, thin-walled cylinders (6a), (6b), etc. are inserted with a gap 11A (10) provided therebetween, and the gap (10) is used as a hydraulic fluid flow port. Effect] By inserting a thin-walled cylinder with a somewhat small diameter into the horizontal evaporation tube and forming a slit between the inner wall of the tube and the thin-walled cylinder, the surface tension of the working fluid causes the interaction between the working fluid on the inner surface of the tube and the thin-walled cylinder. In order to increase the contact area and obtain a high heat transfer coefficient, the smaller the l1ll gap, the more effective it is.Also, if the horizontal evaporation tube is short, the tops of both ends of the thin-walled cylindrical body are vapor flow ports, and the top is ft fluid flow ports. However, if the horizontal evaporation tube is long, the exhaust of steam and the supply of liquid will be insufficient, causing dryout. In this case, it may be necessary to Forming a steam flow port and installing a hydraulic fluid flow port in the lower axial direction c), or inserting multiple short thin-walled cylinders with gaps between them, will prevent steam discharge and hydraulic fluid supply. I pray that it will be done to the fullest.

〔Example〕

(1) A stainless steel pipe with an outer diameter of 60.5 mm, a wall thickness of 1.5 m, and a length of 1320 mm, with a height of 12.7 mm and pips on the outer periphery.
A horizontal evaporation tube with a 4.5-inch radial fin and a fin diameter of 27. +8 s, twin outer diameter 5L 25 ms finch''-/ to form a thermal cycle as shown in Fig. 3, and inside the horizontal evaporation tube as shown in Fig. 1 (a) and (b). Width 15ams 20m in the upper axial direction, 3
Outer diameter 35Ml, 11.45m, 52M, 57111 with slit-shaped steam flow ports of 0#l, 40#l#l
111, a stainless steel cylindrical body with a wall thickness of 1.2#I+ was inserted, and the evaporative heat transfer coefficient within the tube was measured, and compared with the case where the cylindrical body was not inserted into the evaporation tube.

As a result, the heat and light heat transfer coefficient inside the tube is 1 when no cylindrical body is inserted.
It was 500-3000Kcal/-IILh'C, but when the cylinder is inserted, it is 4000-7000Kca
l / TIth ”C.In addition, the evaporative heat transfer coefficient in the tube increases as the outer diameter of the inserted cylinder increases, and the narrower the slit i+, the better it is.
, the outer diameter of the cylindrical body is 52.~! The highest in-tube heat transfer coefficient was obtained with 1711111.

(2) S with outer diameter 50.8 scale, wall thickness 2 scale, and length 3000M
The outer periphery of the tube material made of T B 35 has a thickness of 5 pcc 111111. 5M row with height 12.7aI+
The radial fins were formed by attaching them at a pitch of . This is placed horizontally and the outside diameter 4 made of 5US304 is placed inside the pipe.
41111. Wall thickness 0.8#I#I, length 2995+1#
A cylindrical body with a slit having a width of 10 mm in the vertical direction and the upper axis was inserted to form the horizontal evaporation tube shown in FIGS. 1(a) and 1(b). Also, outer diameter 441 made of 5US304
1m, wall thickness 0.851#I, length 495III+
Insert circular bodies with slits of cl]IoM in the direction of 1 part axis 1 at intervals of 6 mm and 5 mm, as shown in Figure 2 (a).
, (b) Form a small horizontal evaporation tube. Water is supplied as a working fluid into both evaporation tubes at a ratio of 40 vol 1%, and 40 x 103 Kcal / 7 Ith ・”I
Heat forging of O' Kcal/mb was added and the evaporative heat transfer coefficient was measured.

As a result, the song name is 4000-7000Kcal / 1T
Lh “C1 latter is 4000-8500Kcal/
An evaporative heat transfer coefficient of mh'C was obtained. For comparison, the evaporative heat transfer coefficient was measured without inserting the cylindrical body.
It was 500-3000Kcal/h"C.

In addition, when the heat flux was increased in the above measurement, the results shown in Figure 1 (
In the horizontal evaporation tubes shown in (a) and (b), working fluid was not supplied near the center of the tube, and a dry-out phenomenon was observed locally. No similar abnormality was observed in the tube even when the heat flux was increased.

(Effects of the Invention) According to the present invention, it is possible to not only easily remove dust [-] adhering to the outer surface, but also to improve the evaporative heat transfer coefficient within the tube and improve the performance of the heat exchanger. It is effective.

[Brief explanation of the drawing]

Figures 1 (a) and (b) (1) show an example of the horizontal evaporation tube of the present invention, (a) is a side sectional view, (1'') is a cross sectional view, and B) shows an example of the horizontal evaporator tube of the present invention, (A) is a side sectional view, (B) is a cross-sectional view, and FIG. 3 is an example of a heat exchanger using the horizontal evaporator tube. FIG. 1...Horizontal evaporation pipe 2...Condensation pipe 3...Steam pipe 4...Condensate pipe 5...Working liquid 6...Thin-walled cylinder 7...Slit 8...Steam Flow port 9...Fin 10...Gap

Claims (4)

[Claims] (1) In an evaporation tube that is installed horizontally in the evaporation section of a heat exchanger and heats the internal working fluid from the outside to evaporate it, a slit is formed between the tube and the inner wall to allow steam to flow through the top. A horizontal evaporation tube for a heat exchanger, characterized in that a thin-walled cylindrical body having a working fluid flow port at the mouth and the bottom is inserted. (2) Claim 1, which forms continuous or discontinuous hot air flow ports at both ends and/or in the upper axial direction of the thin-walled cylindrical body.
Horizontal evaporation tube for heat exchanger as described in Section 1. (3) A horizontal evaporation tube for a heat exchanger according to claim 1 or 2, wherein discontinuous working fluid flow ports are formed at both ends and/or in the lower axial direction of the thin-walled cylindrical body. (4) A plurality of thin-walled cylindrical bodies are inserted into the pipe by inserting a gap therein, and the upper part of the gap is a vapor flow port and the lower part is a hydraulic fluid flow port. Horizontal evaporation tube for heat exchanger according to item 3.