JPS6269097A - Heat transfer tube - Google Patents

Abstract

PURPOSE:To hermetically fix a circular tube to a flat plate positively for a long time to improve the heat transfer function and facilitate assembling of parts by cooling a flat plate after allowing the plate to memorize the shape and to have a width which is smaller than the distance between engaging ports, heating the flat plate after inserting into the circular tube to restore the shape into a flat plate, and hermetically fixing the plate between the engaging portions. CONSTITUTION:A flat plate 20 constituting a heat transfer tube is made of a material having a shape memory property at high temperatures. The width l3 of the heat transfer tube is slightly larger than a distance l2 between grooves, and the thickness (t) of the plate is slightly smaller than the width l1. The plate 20 in this state is allowed to memorize the shape at high temperatures, thereafter, the plate 20 cooled and folded in two parts from the center, and bent so that the width l4 becomes sufficiently smaller than the distance l2 between grooves, is inserted into a circular tube 10, heated, and restored in shape to a flat plate, and hermetically fixed between grooves which form fixing portions on a sectional centerline (m) thereby to form a heat transfer tube. Since a stress is applied to contact surfaces 31 and 32 of the flat plate 20 and the circular tube 10, it is possible to positively hermetically fix the flat plate and the circular tube and, in addition, to reduce the thermal resistance. Therefore, an excellent heat transfer function can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to heat exchanger tubes used in heat exchangers.

Conventional technology In order to improve the performance of heat transfer tubes used in cross-fin tube heat exchangers, which are often used in air conditioners, etc., in order to promote heat transfer, 1. Increase the heat transfer area. , 2. To make the temperature boundary layer thinner to increase the temperature gradient, and 3. To prevent turbulence. Conventional heat transfer tubes have the structure shown in Figures 9 and 10. there were.

That is, there was a heat exchanger tube 60 in which a flat plate 5o was inserted into a circular tube 4Q and fixed on the cross-sectional center line m.

Furthermore, two methods have been used to tightly fix the flat plate 6o and the circular tube 40.

That is, grooves, for example, grooves 41 and 42 having a U-shaped cross section, are formed in the longitudinal direction in the circular tube on the center line m of the cross section. One method is to insert a flat plate 50 whose width is slightly smaller than the inter-groove distance I16, which is the distance between the fixed parts, between the grooves and to tightly fix the plate 50 with an adhesive or the like.

The other is a flat plate 5Q with a slightly larger width than the groove distance 26, which has elasticity, and is bent into an arched shape to make the width smaller than 24.
This was a method in which the flat plate 5o was inserted into the groove and then tightly fixed by the restoring force of the flat plate 5o.

Problems to be Solved by the Invention However, in such a method, the presence of an adhesive or the like between the circular tube 4o and the flat plate 50 increases thermal resistance, making it difficult for heat to be transmitted from the flat plate 50 to the circular tube 40. There was a problem that there was a possibility of peeling off after long-term use.

In addition, in other methods, the ratio of the length of the flat plate in the longitudinal direction to the width is large (the effective length of the heat exchanger is so
] + Inside the tube 8, 8 (mm: ] Approximately 5
5:1), there was a problem in that it was very difficult to form a heat exchanger tube by bending the entire flat plate in an arcuate shape in the width direction and inserting it into a circular tube.

The present invention takes into consideration the above-mentioned conventional problems, and improves heat transfer performance by firmly fixing a circular tube and a flat plate in close contact for a long period of time.
The purpose is to provide a heat exchanger tube that is easy to assemble.

Means for Solving the Problem In order to solve this problem, the present invention consists of a circular tube and a flat plate made of a material having shape memory, and the circular tube has a reservoir that engages both ends of the flat plate. are provided so as to face the inner surface of the tube, the flat plate has a width larger than the distance between the engaging parts, and the flat plate is shaped at a high temperature and then cooled to form a width smaller than the distance between the engaging parts. After inserting into the circular tube, the flat plate is heated to restore the flat plate shape and tightly fixed between the engaging portions.

Function: With this configuration, the circular tube and the flat plate can be tightly fixed together for a longer period of time than in conventional heat exchanger tubes, and assembly can also be made easier.

EXAMPLE Hereinafter, an example of the present invention will be explained based on FIGS. 1 to 8.

3 and 4 show circular tubes constituting the heat exchanger tube of this embodiment.

10 is a hollow circular tube, and a U-shaped groove 11 is provided in the longitudinal direction as a fixing part for fixing the flat plate to the inner surface of the tube on the cross-sectional center line m.
．． 12 are provided.

The width of the grooves 11 and 12 is C, and the distance between the grooves is 22.

6 and 6 show a flat plate 2o constituting the heat exchanger tube of the present invention, which is made of a material that has shape memory at high temperatures. Wide flood. is slightly larger than the groove distance dan2 and the plate thickness 1j
:n, slightly smaller than . In this state, it is heated to a high temperature to memorize its shape.

FIG. 7 and FIG. 8 show the shape of the flat plate 20 when the flat plate 20 is memorized, cooled, and inserted into the circular tube 1Q.

The flat plate 2Q is folded in half from the center and bent so that the width C4 is sufficiently smaller than the distance between the grooves of 2°.

Figures 1 and 2 show a flat plate 2° folded in half inserted into a circular tube 10 and heated to restore its shape to a flat plate, and between the grooves that are the fixed part on the cross-sectional center line m. A 3° heat exchanger tube formed by tightly fixing is shown.

The width 23 of the flat plate 2Q is the distance between the grooves I! , 2, so the contact surface between the flat plate 2o and the circular tube 10 is 31.32.
Since stress is applied to the tube, the flat plate and the circular tube can be securely fixed in close contact with each other, and the thermal resistance can be reduced, so good heat transfer performance can be obtained.

Furthermore, assembly is easy because the flat plates can be tightly fixed by simply heating them.

In this example, a groove with a U-shaped cross section was provided as the fixing part, but a protrusion with a U-shaped cross section may also be provided, as long as there is a part for fixing the flat plate on the inner surface of the tube on the center line of the cross section. good.

Further, although the flat plate is not processed in this embodiment, a flat plate with protrusions provided on the surface may be used in order to further enhance the heat transfer promoting effect by thinning the temperature boundary layer.

Furthermore, in order to increase the contact area between the flat plate and the circular tube, a flat plate whose end surface is bent into an L-shape may be used.

Effects of the Invention As described above, the present invention is composed of a circular tube and a flat plate made of a material having shape memory, and the circular tube has retaining portions that engage with both ends of the flat plate on opposite sides of the inner surface of the tube. The flat plate has a width larger than the distance between the engaging parts, the flat plate is shaped at a high temperature and then cooled to have a width smaller than the distance between the engaging parts, and after being inserted into the circular pipe, By heating the flat plate to restore its shape to a flat plate and tightly fixing it between the engaging parts, the circular tube and the flat plate are securely fixed for a long period of time, improving heat transfer performance and making assembly easier. This has the effect of making it easier.

[Brief explanation of drawings]

Fig. 1 is an assembled sectional view of a heat exchanger tube in an embodiment of the present invention, Fig. 2 is an assembled side view of the same heat exchanger tube, and Fig. 3 is a cross section showing a single circular heat exchanger tube in an embodiment of the present invention. Figure 4 is a side view showing a single circular tube of the heat exchanger tube, Figure 5 is a front view showing a flat plate of the heat exchanger tube, Figure 6 is a side view of the flat plate, and Figure 7 is a front view of the flat plate. 8 is a side view of the same flat plate, FIG. 9 is an assembled sectional view of the conventional heat exchanger tube, and FIG. 10 is an assembled side view of the same heat exchanger tube. 10...Circular pipe, 2o...Flat plate, 3o...
... Heat exchanger tube, 33.34 ... Fixed part. Name of agent: Patent attorney Toshio Nakao and 1 other Tadayoshi
1 Figure 2 JO-1 yen coin

Claims (1)

[Claims] It is composed of a circular tube and a flat plate made of a material having shape memory, and the circular tube has engaging parts that engage with both ends of the flat plate facing each other on the inner surface of the tube, and the flat plate has a distance between the engaging parts. The flat plate has a larger width, is shaped into a flat plate by causing the flat plate to memorize its shape at a high temperature, and then cooling to form a width smaller than the distance between the engaging parts, and after being inserted into the circular tube, the flat plate is heated and shaped into a flat plate. The heat exchanger tube is recovered and tightly fixed between the engaging portions.