JPS6115091A - Heat transfer tube for 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 spiral wire made of fine wires of copper of a copper alloy, having a winding diameter of a dimension substantially equal to the diameter dimension of the tube inner diameter to the inner surface of a metal tube having a smooth inner surface or a grooved inner surface. CONSTITUTION:A fine wire 2 made of copper or a copper alloy is beforehand wound around a winding core rod having a diameter which is slightly smaller than the inner diameter dimension of a tubular body 1 at an equal pitch or at a dense pitch, and is inserted into the tubular body 1 together with the core rod when the fixing of both ends of the fine wire 2 is released, the winding diameter of the fine wire 2 becomes naturally large by a spring-back force of the fine wire 2, and the clamping on the core rod of a spiral wire 3 is loosened. Hence, the core rod can be drawn out of the tubular body 1, and the wire 3 is closely fixed to the inner surface 1a of the tubular body 1 by a spring-back stress. Thus, the wire 3 is positively secured thereto by the extraction method or the roll pressing method. Further, the heat transfer efficiency is improved by the increase in the inner surface area, generation of the turbulent flow, and occurrence of the capillary phenomenon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat transfer tube for a heat exchanger used in an air conditioning refrigerator or the like.

[Conventional technology]

Heat transfer tubes for heat exchangers that have been put into practical use in the past are made of copper or copper alloy in order to increase heat transfer efficiency. There is a type of tube that forms a spiral groove.

[Problem that the invention seeks to solve]

By the way, as we know, in order to increase the heat transfer efficiency in heat transfer tubes, (a) Cover the electric heating area by a large amount.

(b) Making it easier to cause nucleate boiling.

(c) It becomes easier to cause capillary action.

(d) Turbulence becomes more likely to occur.

This is considered to be effective.

On the other hand, the above-mentioned conventional heat exchanger tubes, especially smooth tubes, have not yet reached the point where the above items have been reduced to 'fA', and therefore, heat exchanger tubes with -L thermal efficiency are required. is the current situation. Furthermore, among the L2 heat exchanger tubes, grooved tubes are mainly manufactured by the rolling method, and this method requires slow processing speed, and due to the rolling technology, the helical multiplier, twist angle, etc. However, there are drawbacks such as the IJ11 limit, and therefore performance cannot be improved at the expense of manufacturing efficiency.

This invention was made in view of the above two circumstances, and aims to provide a heat exchanger tube that has high thermal efficiency and can be easily manufactured.

Means for Solving Problem F" This invention provides a copper or copper alloy with a winding diameter that is approximately the same as the inner diameter of the tube on the inner surface of a tube W1 made of copper or copper alloy with a flat or grooved inner surface. It is made of IBIil spiral wire tightly fixed.

"Operation" According to the above configuration, the surface area of the inner surface of the tube is greatly increased by the spiral wire closely fixed to this inner surface,
The flow of fluid inside the tube also becomes turbulent due to the spiral wires, and if the pitch of the spiral wires is made dense, fine continuous gaps are formed on the inner surface of the tube, which causes capillary phenomenon, and the gaps create nucleation. Boiling occurs more easily, and as a result, heat transfer efficiency is greatly improved. Also, the spiral wire should be tightly attached to the inner surface of the tube.

Simple joining methods such as plating, and simple mechanical methods such as inserting a spiral wire into the tube and then subjecting the steel tube to handling Y or roll If shrinking. This makes manufacturing easier.

This firing will be explained below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a first embodiment of the present invention, and the reference numeral 1 in the figure indicates a tube made of copper or copper alloy. The inner surface 1a of this tube body 1 is smooth, and this inner surface 1a
A spiral wire 3 made of copper or copper alloy fine wire 21Il is closely fixed to the wire.

The spiral wire 3 can be formed by simply winding a copper or copper alloy thin wire around a core material at equal pitches or close to 4 bits. It is determined. In practice, the spiral wire 3 is closely fixed to the inner surface 1a of the tube body 1 in the following manner. First, copper or copper alloy wire! i12 in advance to tube body 1
The thin wire 2 is wound at equal pitches or close pitches using the inner diameter q method, and is inserted into the tube body 1 together with the core rod, after which both ends of the thin wire 2 are unfixed.

Then, the winding diameter of the thin wire 2 naturally increases due to the springback force of the thin wire 2, and the 4J force tightening the spiral thin wire 2 (spiral wire 3) against the core rod is loosened, so the core rod is attached to the tube body 1. Bring it out from within.

Even in this state, the spiral wire 3 is tightly fixed to the inner surface 1a of the tube body 1 due to the springback stress of the warp, but it can be firmly fixed tightly by any of the following four methods.

(D A plug that fixes the pipe body 1 inside it or) 0
- Insert the tubing plug or insert the cape, or pass through the drawing die without inserting anything.
This is done by reducing the diameter (Kawabe method).

α) This is done by squeezing the tube 1 with two opposing rolls with semicircular calibers or two pinch-type rolls (roll sweat removal). Apply flux, then insert a solder wire, then heat using an induction heater or bright annealing furnace while introducing an inert gas or reducing gas, and perform soldering (waxing (JL method)). ), In this case, if the wire 2 is plated with a low-melting white metal such as gold in advance, the above-mentioned 0 mark can be easily attached.

(2) Filling the tube 1 with a plating solution and an anode and using the tube 1 as a cathode, plating the tube 1 (plating method).

The spiral wire 3 that is closely fixed to the inner surface 1a of the tube body 1 as described above may be formed at a predetermined pitch, but as shown in the figure, the spiral wire 3 and the tube can be formed at a close pitch. A spirally continuous gap 4 can be easily formed between the body 1 and the inner surface 1a.

According to the heat exchanger tube having the following structure, the following advantages can be obtained.

(1) The spiral wire 3 greatly increases the inner surface area of the shield 1, improving heat transfer efficiency.

The winding direction of the spiral wire 30 can be set to nearly 90 degrees with respect to the axial direction of the tube 1 (the flow direction inside the tube 1), and as a result, the flow inside the tube 1 is made more turbulent. This can improve heat transfer efficiency.

(C) By setting the pitch of the spiral wire 3 to the close pitch, a continuous capillary tube (gap 4) can be formed between the spiral wire 3 and the inner surface 1a of the tube body 1, thereby improving heat transfer efficiency. can be achieved.

(The copper or copper alloy thin wire 2 constituting the small spiral wire is extremely easy to obtain, and the spiral wire 3 is also easy to manufacture.

(e) The minimum winding diameter of the spiral wire 3 is limited only by the minimum manufacturing dimension of the winding core fL collar, so it is possible to form windings with an extremely small winding diameter.
It is also possible to manufacture extremely thin heat exchanger tubes with a diameter of 3 mm or 3 mm.

[Embodiment 2] Figures 2 and 3 show a second embodiment of the present invention, and the parts common to Figure 1 are indicated by the amount of copper minus the code 1.
This will simplify the explanation. Reference numeral 5 in the figure indicates the inner surface 1a of the tube body 1.
This figure shows the thin copper or copper alloy wire that constitutes the spiral wire 3 that is closely fixed to the wire. The difference between this thin wire 5 and the thin wire 2 in Example 1 is that a notch (cut groove) 5a is formed on its outer peripheral surface. This notch 5a is
It may be provided intermittently in the axial direction on one side of the thin wire 5 as shown in Figures 2 and 3 (al), or intermittently in the axial direction in a ring shape as shown in Figure 3. It is also possible to provide them continuously in a spiral shape as shown in FIG. 3(C).

When the notch 5a is formed in the thin wire 5 constituting the spiral wire 3 as described above, the spiral wire 3 and the inner surface 1a of the tube body 1
A large number of openings 5 that open inside the tube body 1 can be formed in the interval (71! continuation capillary tube) 4 formed between the tube body 1 and the tube body 1 .

Therefore, in this embodiment, in addition to the advantages obtained in the embodiment 51 above, the following new advantages can be obtained. Also, in F), a bubbling phenomenon (nuclear boiling) occurs from the opening 6, and as a result, 4
[This has the advantage that the refrigerant in the tube body 1 enters the gap 4 from the foaming phenomenon q4T, and boiling is promoted, and furthermore, the formation of the open part 6 improves heat transfer. The surface area is larger and the turbulence forming effect is also increased.

"Embodiment 3" FIG. 4 shows the main part of the third embodiment of the present invention, and the reference numeral 7 in the figure indicates the spiral wire 3 which is closely fixed to the inner surface 1a of the tube body 1 as described above. This shows the constituent copper or copper alloy fine wire. As shown in the figure, this thin line 7 is
This is a stranded wire made of ultrafine wires 7a of copper or copper alloy.

If the thin wires 7 constituting the spiral wire 3 are twisted wires, there will be a large number of strands in the continuous interval ('4 continuation capillary tube) 4 formed between the spiral wire 3 and the inner surface 1a of the flute body 1. Therefore, ten of the same advantages as in the second embodiment can be obtained, and these advantages can be further increased.

"Embodiment 4" FIG. 5 shows a fourth embodiment of the present invention, in which reference numeral 8 denotes the spiral $! j! 3 shows the copper or copper alloy thin wire constituting No. 3. This thin wire 8 is formed by forming a single copper or (J copper alloy) ultra-thin wire 8a into a minute diameter spiral.

In this embodiment, the only difference is the thin wire 8 constituting the spiral Fj13 as described above, and the other shapes are the same as in each of the above embodiments.

By configuring the heat exchanger tube according to the present invention as described above, the same advantages as in the third embodiment can be obtained.

In each of the above embodiments, the tube body is a smooth tube, but the heat exchanger tube of the present invention can be applied not only to a smooth tube but also to a grooved tube.

"Effects" As explained above, the heat exchanger tube according to the present invention has a copper or copper alloy tube with a smooth or grooved inner surface and a copper coil having a winding diameter that is approximately the same as the inner diameter of the tube. Or a spiral wire made of fine copper alloy wire fixed in secret6.
Therefore, in the heat exchanger tube of the present invention, the surface area of the inner surface of the tube is greatly increased by the spiral wire closely fixed to the inner surface, and the flow of fluid inside the steel tube is also disturbed by the spiral wire. If the pitch of the spiral wires is made dense, a narrow continuous gap will be formed on the inner surface of the tube, which will cause a capillary phenomenon, which will cause nucleate boiling to occur more easily, and as a result, the heat transfer efficiency will decrease. Significantly improved. In addition, the spiral wire can be tightly fixed to the inner surface of the tube by simple bonding methods such as rowi 1 or plating, and after the spiral wire is inserted into the tube, it is handled and applied to the steel tube.
It is easy to manufacture because it can be carried out by simple mechanical methods such as rolling or roll compression.

Finally, in order to quantitatively confirm the effects of the present invention,
An example will be shown in which a heat transfer tube was manufactured by the following method based on the first example, and its heat transfer 1) bamboo was investigated.

"Example" Outer diameter 9.6am+φ, wall thickness 0.33m, length 2000m
Using a phosphorus-deoxidized copper tube (tube body), the inner surface of the tube was degreased by trichlorethylene linear treatment. -10,000,0.3a* of copper
φ fine wire to 711IIRφ coil winding core metal rod <SUS
A thin polishing rod of 2000 txm was applied between the coil windings.
Wind it up with a winding pitch of 45 knots, fix both ends so that it does not come loose, insert it into a phosphorus-deoxidized copper pipe, and then
Both ends were released. The thin copper wire inside the top phosphor deoxidized copper tube was released from the coil-wound metal rod by springback and was tightly attached to the inner surface of the copper tube with a winding pitch of 0°6Hn.
The released core metal rod was extracted from the inside of the copper tube.

In addition, the adjustment method θ, 1, which makes use of the springback stress of the spiral wire made of thin copper wire and brings the spiral wire into close contact with the inner surface of the copper tube at equal pitches, is based on the mechanical I of the wire.
It is determined by IL (tensile strength, elongation yield value), physical properties (V-leg ratio), twist of the wire, wire diameter, and winding (J, etc.).

The steel pipe containing the copper spiral wire manufactured as described above does not fit tightly due to variations in the winding diameter of the spiral wire and the ellipticity of the steel pipe itself, and there may be slight gaps left locally. There may be cases.

Therefore, the above-mentioned copper tube was passed through a drawing die and subjected to dry drawing at a reduction rate of 1% in outer diameter so that the spiral wire was completely tightly attached to the inner surface of the tube.

After that, water-soluble Norax for soft D bones was injected into the inner surface of the tube, and soft solder material (Sn-Pb=6:4) 2.5 #
φ, length 2000mm, and this steel pipe was heated at 10IIl per minute in a high frequency induction heater under N2 gas flow.
The wire was tightly fixed to the inner surface of the copper tube. In addition, in order to prevent oxidation of the copper tube during heating, cooling with N2 gas was performed immediately after heating. After washing the inner surface of the bamboo heat transfer tube made in this way with water, it was confirmed that waxing was complete over the entire length.

The heat exchanger tube manufactured as described above has an outer diameter of 10°05I.
*Vi tube expansion was performed by inserting a plug over the entire length until it reached IIllIφ, but no peeling of the spiral wire was observed.

The heat transfer tube was also tested using the heat transfer N-bamboo test apparatus shown in FIG. In this device, T is humidity sensor 9, P is perspiration rate, P
D is the difference B-31, 30 is the pump, 31 is the valve, 32
Let flow φM, 33 is an expansion valve, 341! ] Nbulets υ,
35 Haribundenri, 36 is 1 knob Tbaboira, 37
is a constant temperature water tank, and 38 is a heat exchanger tube as a test tube. The evaporation, condensation, and condensation tests were conducted using a 5 m straight heat transfer tube and using refrigerant R22 under the following experimental conditions f1.

Evaporation test Condensation test refrigerant flow m (Kg/H) 40,
60,80 40,60.80 Evaporation temperature (℃)
5 Overheating marks near 5 cases (℃)
5;-0,55i4 Near condensation temperature ('C) 4
! + 45 degree of supercooling (℃) 10'' -0,55
Size 05 Water Φ (J/min) 9.0 9
．． 0 water 'i = ('C)
15~25 25~,35 In this case, the IJ water temperature is controlled so that the refrigerant system is stabilized at the peak of each refrigerant flow ff1 (H/ I operated the valve to make sure. Arrows A and B in FIG. 6 indicate the flow directions of refrigerant and water in the case of the evaporation test, respectively, and arrows B and B- indicate the flow directions of the refrigerant and water in the case of the condensation test, respectively.

As a result of this test, it was found that the heat transfer tube C obtained by the method of the present invention had excellent heat transfer characteristics as shown in FIG. In addition, the comparative example is the result in the case of a smooth steel pipe and a steel pipe with a vortex of 5 m.

[Brief explanation of drawings]

FIG. 1 shows a first embodiment of the present invention, and shows a partially cutaway perspective view of a heat exchanger tube according to the present invention, and FIG. C) is a side view of a thin wire constituting a spiral wire in a heat exchanger tube, and FIG. 4 shows a third embodiment of the present invention, and is a perspective view of a spiral wire constituting a heat exchanger tube according to the present invention. , FIG. 5 shows a fourth embodiment of the present invention, which is a perspective view of the spiral wire constituting the heat exchanger tube according to the present invention, and FIG. 6 shows the measurement of the heat transfer characteristics of the heat exchanger tube according to the present invention. FIG. 7 is a block diagram of a test device suitable for the above-mentioned test device, and is a graph 2 showing the heat transfer special bamboo planting of the heat transfer tube of the present invention measured by the test device. 1...Pipe body, 1a...Inner surface, 2.5.
...Thin wire, 3...Spiral wire, 4...
... Gap (continuous capillary), 5a ... Cut groove, 6 ... Opening, 7 ... Thin wire (twisted wire), 8 ... Thin wire (spiral thin wire), 7a,
8a...extremely thin wire.

Claims (3)

[Claims] (1) A spiral wire made of fine copper or copper alloy wire with a winding diameter approximately the same as the inner diameter of the tube is closely fixed to the inner surface of a tube made of copper or copper alloy with a smooth or grooved inner surface. Heat exchanger tubes for heat exchangers. (2) The heat exchanger tube for a heat exchanger according to claim 1, wherein the copper or copper alloy thin wire is composed of a spiral ultrafine wire, a stranded wire, or a braided wire. (3) The heat exchanger tube for a heat exchanger according to claim 1, wherein cut grooves are formed continuously or intermittently on the outer peripheral surface of the thin copper or copper alloy wire.