JPH0441276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heat transfer tube in which a large number of wavy wire fins are fixed to the inner surface of the tube wall to improve the condensation and evaporation effects of the heat medium inside the tube.

(Conventional technology) Heat exchangers are often used in industrial fields such as refrigeration and air conditioning, but the efficiency of these heat exchangers is greatly affected by the performance of the heat transfer tubes used. In order to improve the performance of machines, etc., there is an urgent need to improve the performance of heat transfer tubes.

By the way, in the case of refrigeration equipment equipped with a heat pump function, the demand for which has recently increased significantly, the flow path of the refrigerant piping is switched depending on the season, and two heat exchangers installed indoors and outdoors are used as a condenser and an evaporator. Therefore, it is important for the performance of heat transfer tubes used in such heat exchangers to be able to perform both condensation and evaporation in a well-balanced and efficient manner within the same tube. It becomes an element.

(Problem to be solved by the invention) However, the so-called high-performance heat transfer tubes used in conventional heat exchangers have not been improved to increase the efficiency of either condensation or evaporation due to their intended use. Because of the emphasis placed on heat pumps, performance has become uneven, and the reality is that even when used in heat exchangers for refrigeration equipment equipped with the heat pump function, sufficient efficiency improvement cannot be expected.

Although somewhat outside the technical field of refrigeration equipment, there is a heat pipe that condenses and evaporates a heat medium in the same tube.

This heat pipe is generally made by lining the inner surface of a sealed heat transfer tube container (also called a container) with a porous material called wick, such as wire mesh, fiber, felt metal, etc. It is constructed by impregnating the wick with an evaporative liquid and enclosing it, and the evaporative liquid actively evaporates and condenses within the container due to the action of the wick, efficiently transferring heat between both ends of the container. It is known that this can be done rapidly, and therefore, if these heat pipe structures are applied to the heat transfer tubes of a heat exchanger, evaporation and
It should be possible to manufacture heat exchanger tubes with excellent condensation properties.

However, the heat pipes of this type that have been proposed in the past are simply inserted into a heat exchanger tube container.
In the heat pipe disclosed in Publication No. 175888, a spiral band-shaped wick is inserted so as to be in contact with a groove on the inner surface of the container, and the wick is supported by a plate-shaped support wick inserted in the center and pressed against the inner surface of the container, or As disclosed in Japanese Utility Model Application Publication No. 58-27666, a multi-coil wire made by winding a small-diameter coiled wire into a larger-diameter coil is used to create a container by utilizing its outward restoring force. (container), but none of these methods can reliably join the pipe to the inner wall of the pipe, and are merely in contact with the pipe, resulting in poor adhesion. Therefore, there is a slight difficulty in heat transfer between the wick and the heat exchanger tube container, and in the case of the former case where a support wick that crosses the tube flow path is housed inside the heat exchanger tube container, the flow resistance of the fluid in the tube is significant. There is a possibility that this may actually cause a decrease in efficiency.

As described above, conventional heat pipes have problems with their heat pipe mounting structure, and applying this as is to heat exchanger tubes for heat exchangers leaves many problems in terms of efficiency and manufacturing.

The present invention was made by focusing on the performance problems of such conventional heat exchanger tubes. The condensation and condensation in the pipe are formed
The present invention aims to improve the efficiency of both evaporation and increase the heat transfer coefficient between the corrugated wire fins and the heat transfer tube, thereby comprehensively solving the above-mentioned problems.

(Means for Solving the Problems) The configuration of the present invention for achieving the above object is described as
The figure and FIG. 2 will be explained.

The heat exchanger tube 1 of the present invention includes a large number of wavy wire fins 2 arranged in parallel along the tube axis direction over the entire circumference of the inner surface 1a. It is welded and fixed to the inner surface via a brazing material layer 3 having relatively high thermal conductivity such as solder.

In addition, dimensional elements such as the thickness of the strands of the wavy wire fins 2 welded and fixed to the inner surface 1a of the heat exchanger tube 1, the arrangement pitch, the fin height, and the waveform pitch are as follows.
The assembly of the wavy wire fins 2 forms a wick 4 that efficiently condenses and evaporates the fluid in the pipe.The wire diameter d is 0.1 to 0.6 mm, the fin height is H,
When the heat exchanger tube inner diameter is D, H/D is 0.05 or less,
It is effective that the circumferential pitch Pr is 1.3 to 3d with respect to the wire diameter d, and the waveform pitch Pw is 1 to 3H with respect to the fin height H.

(Function) When the heat exchanger tube 1 of the present invention having the above configuration is used as a heat exchanger tube constituting a condenser or evaporator of a refrigeration system by passing a refrigerant such as fluorocarbon into the tube,
Each wavy wire fin 2 has its arrangement direction aligned with the tube axis 0.
The wavy wire fins 2 are parallel to each other and do not obstruct the flow of the refrigerant inside the heat transfer tube 1 and smooth the movement of the liquid refrigerant or gas refrigerant. , promotes evaporation and condensation of refrigerant, and exhibits excellent performance regardless of whether the heat exchanger is used as a condenser or evaporator. Furthermore, since each wavy wire fin 2 is welded and fixed to the inner surface of the heat exchanger tube 1,
It is possible to maintain a high heat transfer coefficient between the fins and fully perform the function as a fin, and to perform heat exchange efficiently.

(Example) Examples of the present invention will be described in detail below based on the accompanying drawings.

FIG. 1 is a side view of a heat exchanger tube according to the present invention, and FIG. 2 is a front sectional view of the same heat exchanger tube.

In these figures, 1 is a heat exchanger tube made of a high-purity copper pipe or the like, and the heat exchanger tube 1 is arranged on its inner surface 1a at equal intervals parallel to the tube axis 0 over the entire circumference. It is equipped with a large number of wavy wire fins 2, and each wavy wire fin 2
are welded and fixed to the inner surface 1a of the heat exchanger tube 1 through a brazing material layer 3 having high thermal conductivity such as solder, and evaporated onto the inner wall surface of the heat exchanger tube 1 by the aggregate of these wavy wire fins 2. - Wick 4 is formed to promote condensation.

The wavy wire fins 2 are made of copper wire or aluminum wire with good thermal conductivity, and the wire diameter d, fin height H, fin pitch Pr in the circumferential direction of the heat exchanger tube, and waveform pitch Pw are set to values within a predetermined range. By setting it to ) is preferably within the size range.

Wire diameter d: d = 0.1 to 0.6 mm ... (a) Fin height H: H = (2 to 4) d ... (b) Circumferential fin pitch Pr: Pr = (1.3 to 3) d
...(c) Waveform pitch Pw: Pw = (1 to 3)H ...(d) For example, the wire diameter of the wavy wire fin 2 is 0.2 in consideration of ease of processing and product cost.
mm copper wire, and when the fin height H is 0.6 mm, the fin pitch Pr is 0.32 mm, and the waveform pitch Pw is 1.08 mm, the wick 4 made up of an aggregate of wavy wire fins 2 will have approximately 80 meshes. Become.

This is due to the performance of Utsuku, which is said to have a mesh size of 30 to 300, which is said to actively generate boiling nuclei from the viewpoint of evaporation function, and the droplets are distributed all over the inner wall of the tube due to capillary action, and the droplets are sufficiently retained. included in the range.

In addition, from the viewpoint of condensation, since the thinnest copper wire is used as the wire of wire fin 2, the liquid film on the surface becomes thinner and the liquid drains better, improving condensation heat transfer and condensation. It is possible to maintain high performance.

It should be noted that the fin height H of the wavy fin wire 2 should not be increased unnecessarily from the viewpoint of steam flow resistance, and in particular, the fin height H of the wavy fin wire 2 should not be made excessively large.
On the other hand, when H/D exceeds 0.05, the resistance increases rapidly.

As a means of manufacturing the heat exchanger tube with internal fins of the present invention, the inner surface 1a of the heat exchanger tube 1 made of a copper pipe is plated with solder or the like in advance to form a thin brazing material layer 3, and this is bent into a corrugated shape. Hold the wavy wire fin 2 with a jig etc. and adjust the tube axis to 0.
heat is applied from the outer surface of the heat transfer tube 1 to temporarily melt the brazing material layer 3, and the wavy wire fins 2 are immediately cooled to form their U-shaped shape. It is welded and fixed to the inner surface of the heat exchanger tube 1 only at the bottom surface of the bent portion. In addition, in both the solder plating process on the inner surface of the heat exchanger tube 1 and the welding process of the corrugated wire fins 2, the heat exchanger tube 1
It is preferable to pass a reducing gas such as hydrogen through the oxidation chamber in a reducing atmosphere in order to prevent a decrease in the heat transfer coefficient due to oxidation.

FIG. 3 schematically shows an example of a manufacturing apparatus for such a heat exchanger tube with internal fins, in which 1 is a shield tube having an inner diameter into which the heat exchanger tube 1 can be inserted, and 12 is a shield tube arranged around the outer periphery of the shield tube 11. A heater 13 is provided, and a cooler 14 is provided adjacent to the heater 12.
A plurality of fin guides are housed inside the shield tube 11 and supported in a skewered manner by a rod 16 whose one end is fixed to the side cover 15 of the shield tube 11, and the fin guide 14 is shown in FIG. As shown in FIG. 2, it has a structure in which a number of spline-shaped guide grooves 17 slightly wider than the wire diameter of the wavy wire fins 2 are carved on the outer periphery in a number corresponding to the number of wire fins. . The heat exchanger tube 1 is guided along the inner surface 1a of the heat exchanger tube 1. 22 is a heat exchanger tube holder provided by gripping one end of the heat exchanger tube 1; 23 is a sliding rod for moving the heat exchanger tube holder 22 in the tube axis direction of the heat exchanger tube 11; and 23 is a pulley for guiding the wire fin 2. The end portions of the wavy wire fins 2 guided by the fin guide 14 are bundled and inserted into the center hole 22a of the heat exchanger tube holder 22, and the heat exchanger tube holder 22 is fixed with a set screw 24.
has been concluded.

In the manufacturing apparatus having the above configuration, since the inner surface 1a of the heat exchanger tube 1 has been solder-plated in advance, the heat exchanger tube 1 is moved by the sliding rod 23 to the direction indicated by the arrow X.
While sliding in the direction, the heater 12 heats the heat transfer tube 1 from the outside of the shield tube 11 to melt the brazing material layer 3 on the inner surface, and the cooler 13 provided during the movement heats the heat transfer tube 1 from the outside of the shield tube 11. The heat exchanger tube 1 and the corrugated wire fin 2 are welded together by cooling from the outside. Therefore, if welding is carried out sequentially in the longitudinal direction while moving the heat exchanger tube 1 in the tube axis direction, each wavy wire fin 2 will be guided by the fin guide 14,
It is welded to the inner surface 1a of the heat exchanger tube 1 while maintaining the fin pitch Pr correctly.

When the thus manufactured heat exchanger tube is used as a heat exchanger tube for a heat exchanger that also serves as a condenser and evaporator in a refrigeration system, a wick 4 is formed by a large number of wavy wire fins 2 welded to the inner surface of the heat exchanger tube 1. Since each wavy wire fin 2 is welded to the heat transfer tube 1, a high heat transfer coefficient is maintained between the fins and the heat transfer tube 1. can fully demonstrate its functions.

In the above embodiment, a case is shown in which the wavy wire fins 2 are attached only to the inner surface 1a of the heat exchanger tube 1. However, when the heat exchanger tube of the present invention is used in an erotic fin type or cross fin type heat exchanger, the heat exchanger tube A plane fin or a wavy wire fin is separately attached to the outer surface of 1 as appropriate.

(Effects of the Invention) As described above, the heat exchanger tube with inner fins of the present invention has a large number of wavy wire fins over the entire inner circumference with the required wire diameter, fin height, circumferential pitch, and waveform pitch. The wavy wire fins are arranged in parallel along the tube axis direction, and each wavy wire fin is welded and fixed to the inner surface via a brazing metal layer with high heat transfer coefficient, and the wavy wire fin forms a wick on the inner surface that promotes condensation and evaporation of the refrigerant. Therefore, the wavy wire fins hold the refrigerant in a liquid film state to promote evaporation, and the wire fins are made thinner and the liquid film on its surface is made thinner to promote condensation.
As a result, it exhibits excellent performance in both condensation and evaporation, and greatly contributes to improving the efficiency of the heat exchanger and, by extension, the efficiency of the entire refrigeration system.

Moreover, according to the present invention, each wave-like wire fin is welded and fixed to the inner surface of the heat transfer tube, so the heat transfer tube has excellent stability, and since it does not require a support member like a conventional heat pipe, it can be fixed in the tube axis direction. Coupled with the arrangement, there is no fear of interfering with the flow of refrigerant, and it can be widely used as heat transfer tubes for various heat exchangers.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing an example of the heat exchanger tube with internal fins of the present invention, Fig. 2 is a front sectional view of the heat exchanger tube, and Fig.
The figure is a schematic view showing an example of a manufacturing apparatus for a heat exchanger tube with inner fins according to the present invention, and FIG. 4 is an enlarged cross-sectional view of FIG. 3. DESCRIPTION OF SYMBOLS 1... Heat exchanger tube, 1a... Inner surface, 2... Wavy wire fin, 3... Brazing metal layer, 4... Wick.

Claims (1)

[Scope of Claims] 1. A large number of wavy wire fins with a wire diameter of d0.1 to 0.6 mm are provided along the entire inner circumference of the heat exchanger tube in the axial direction of the tube, with the fin height being H and the inner diameter of the heat exchanger tube being D. Time, H
= (2 to 4) d, and with a fin height where H/D is 0.05 or less, the circumferential fin pitch Pr is (1.3 to 3) d, and the waveform pitch is relative to the wire fin diameter d.
A heat exchanger tube with internal fins, characterized in that Pw is arranged in parallel at (1 to 3) H with respect to the fin height H, and is welded and fixed via a brazing metal layer with high thermal conductivity. 2. The heat exchanger tube with inner fins according to claim 1, wherein a wick is formed on the inner surface of the heat exchanger tube by an aggregate of wavy wire fins, and the wick promotes condensation and evaporation of the heat medium inside the tube.