JPS6115093A - Heat transfer tube for use in heat exchanger - Google Patents

Abstract

PURPOSE:To provide a heat transfer tube of a high heat efficiency which is easy to manufacture by closely fixing a thin tubular body made of copper or a copper alloy, having a diameter dimension substantially equal to the inner diameter of the tubular body, to the inner surface of the tubular body having a smooth inner surface or a grooved tubular body. CONSTITUTION:A copper tube 2 provided with a large number of through holes 2a is defatted washing with trifluoroethylene, and inserted into a copper tube 1. Thereafter, idle elongation is carried out and cold drawing is also carried out and a copper tube 1 attempted to be integrally formed with the porous copper tube 2, and metal cores are inserted into double tubes 1 and 2 to thin the thickness of the copper tube 1 thereby to carry out metal core extraction. As a result, the through hole 2a is elongated in the direction of the extraction axis, and is deformed in an oval hole, and its closely holding force is extremely increased. Further, as a result, the heat transfer area becomes large, and nucleate boiling, capillary tube phenomenon and turbulent flow are easy to occur, and thus the heat transfer efficiency is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heat transfer fK for a heat exchanger, which has been used for a long time in refrigeration ES for air conditioning, etc.

[Conventional technology]

Conventional heat exchanger heat transfer tubes used in practical use are made of copper or copper alloy to increase heat transfer efficiency, and those with a flat inner surface (smooth 'F) improve thermal efficiency roughly. For the inside helical tie f: formed (+
There is a pipe with 4).

[The problem that the invention is trying to solve]

By the way, as is well known, heat transfer 1. ! K increases the heat transfer efficiency in (a) increases the size of the heat transfer sandalwood.

(b) Prevent nuclear explosion.

Pl Facilitates capillary action.

2) fAJ flow occurs and it becomes 9th.

It is said that this is effective.

On the other hand, the conventional heat transfer tubes mentioned above, 44tC smooth tubes, have not yet reached the point where they fully satisfy the above requirements, and as a result, there is currently a demand for better heat transfer and better thermal efficiency. be. Furthermore, among the above-mentioned heat transfer tubes, grooved tubes are mainly manufactured by the transfer method, and this method can process M! , the degree is slow <, it may turn m
Technically speaking, there are drawbacks such as limitations on the number of spiral threads (19), twist angle, etc., and as a result, performance cannot be improved at the cost of sacrificing manufacturing efficiency.

Is this invention mentioned above? This was done in consideration of the above, and the purpose is to provide heat exchanger tubes that have high thermal efficiency and can be easily manufactured.

[Means for solving problems]

The heat exchanger tube according to the present invention has a large number of through holes formed in the inner surface of the tube body made of steel or copper alloy and having a smooth or grooved inner surface and having an outer diameter that is approximately the same as the inner diameter of the tube body. This is a thin-walled tube made of steel or copper alloy that is tightly fixed.

[Effect]

According to the above structure, the surface area of the inner surface of one tube is greatly increased by the through holes of the porous tube that are tightly fixed to the inner surface, and the holes of the parts inside the tube are also increased by the same *31M holes. This leads to overselling, and the through holes make it easier for nucleate boiling to occur, resulting in a significant improvement in heat transfer efficiency. In addition, a porous tube can be tightly fixed to the inner surface of a tube using easy joining methods such as brazing or plating.Furthermore, after inserting the porous tube into the tube, Manufacturing is easy because it can be carried out using sophisticated mechanical methods such as roll compression processing and the like.

Hereinafter, the present invention will be explained with reference to the drawings.

〔Example〕

Outside 4/, 2 amφ, wall thickness a (1 m, length 20θθ
Using the phosphorus deoxidizing steel pipe (C pipe body) 1 (Fig. 1) of Tsumugi, it was not cleaned with trichlorethylene, and the inner surface of the pipe 1a was
Two steps of degreasing were performed.

On the other hand, the outer diameter is /Qmmφ, the wall thickness is Q, the length is 20
A large number of through holes 2 were drilled into the adjacent 00Bm deoxidized steel pipe from the outside with 21 pinches in the axial direction and at 93 degrees in the circumferential direction.
a5: It dawned continuously. After degreasing the steel pipe (porous pipe body) 2 with these through holes 2a by washing with trichlorethylene and inserting it into the steel pipe 1, the outer diameter becomes /0.
．． As a result, the steel pipe lKr1 has been cold drawn by about 30%, and is approximately /,
It has been stretched to 09 times its length. Therefore, the outer l:1
This means that the copper-sae 1 of mφ should be about q1% better than the inserted porous steel pipe 2 of 1014φ. Copper tube 1 which is pressed and integrated with the internal porous mff2 as described above
corresponds to a music pipe with an outer diameter of 1013φ and a wall thickness of ag avr. After that, in order to further reduce the wall thickness, a core metal of 02#Isφ was inserted into the inner surface of the double tube, and a core metal was drawn using a die with an outer diameter of 9, !t and 3mmφ. A double pipe (transfer pipe) with an outer diameter of 9.j3 gφ and a wall thickness of a9 as shown in the figure was fabricated.The cold working rate in this case was approximately /7.g%, and the elongation rate was As a result, the through hole 2aVi was elongated in the direction of the drawing axis and transformed into a circular hole with a major axis of approximately 1.22 times.The minor axis in this case was approximately ag.

The total length of the heat exchanger tube manufactured as described above is 2tItI.
The result was OIuI, and the adhesion retention was extremely high.

Next, the heat transfer tube was tested using a heat transfer characteristic testing apparatus shown in FIG. In this device, T is a degree sensor, P is a pressure gauge,
PDtri differential pressure gauge, 30V'i pump, 31 is valve,
32 flow meter, 33Vi expansion valve, 34Vi humppressor 535tI'i sub-combiner, 36 is sub-evaporator boiler, 37vil1g hot water tank, and 38 is heat exchanger tube as test tube. The evaporation and condensation tests were conducted using a 3 m straight pipe (heat transfer tube) and using refrigerant F422 under the following test conditions.

Evaporation test Condensation test refrigerant flow company ('+9/H) 40, 60, 80 40
,60.80 Evaporation temperature ('C) 5
Superheat degree near 5 ('C) 5±0.5
Condensing temperature around 5 2 ('C) 45
45 Degree of supercooling (“C”) 10±0.55±0.5 Water @
(17 minutes) 9.0 9.0 water W
(''C) 15~2525~35 In this case, the water wetting f: is controlled so that the refrigerant threads are stabilized at each refrigerant fiEJit (kg/H) iσ, and this constant temperature water is applied to the refrigerant flowing into the test tube 38. The pulp was manipulated to be commercially viable.Arrows A and A' in Figure 2 indicate the flow directions of refrigerant and water, respectively, in the case of the evaporation test, and arrow 14113.
B' indicates the flow direction of the refrigerant and water, respectively, in the case of the condensation test.

As a result of this test, it was found that the heat transfer tube CVi obtained by the method of the present invention had a heat transfer characteristic of 72 as shown in FIG. Note that the comparison β is the result for a smooth steel pipe and a grooved pipe of 23 m.

[Brief explanation of the drawing]

FIG. 1 shows an example of a field in which the present invention is applied, and FIG. FIG. 3 is a graph showing the heat transfer characteristic values of the heat transfer tube of the present invention measured by the test bag fVC. 1... deoxidized steel pipe cW body), 1a...
Inner surface, 2... porous 1! ): Steel pipe (porous/A body), 2a...through hole. Figure 1

Claims (1)

[Claims] A heat exchanger tube for a heat exchanger, which has a porous tube having an outer diameter approximately the same as the inner diameter of the tube, which is tightly fixed to the inner surface of a tube made of copper or copper alloy with a smooth or grooved inner surface.