JPS6136693A - Heat pipe - Google Patents

Abstract

PURPOSE:To obtain a heat pipe excellent in a heat transfer performance at a low cost by using non-oxygen copper as a vessel material and forcibly forming an oxidized film on the surface of a groove formed in the inner wall surface of the vessel by use of chemical or thermal means. CONSTITUTION:A tubular vessel 1 is made up of non-oxygen copper, and an oxidized film is formed on the surface of the groove 8. In a case where pure copper is oxidized with chemical means, the surface of copper is covered with a mixture of Cu2O, CuO and Cu2O3 at a ratio depending on the degree of oxidation. These oxides have each an irregular and slender shape, and the surface area thereof is greatly increased, as compared with the flat surface of pure copper. Further since extremely minute recessions and projections are formed between particles of respective oxides, the capillary tube effect with respect to the working liquid greatly increases and wettability is improved. By subjecting the inner surface of the pipe to a chemical treatment in this manner, it can be recognized that the heat transfer performance of the pipe is improved by the formation of the oxidized film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a heat pipe, and particularly to a so-called groove type heat pipe having a large number of thin grooves extending in the axial direction on the inner wall surface of a tubular container.

[Prior art] Figures 2 and 3 explain the most basic function of a heat pipe. In Figure 2, a closed container 1 placed horizontally
When the inside is filled only with the working fluid 2 and its vapor, the working fluid 2 is evaporated by applying heat to one end in the direction of the arrow 3.

On the other hand, by cooling the other end and absorbing heat in the direction of the arrow 4, a Jf force difference is generated in the container 1, and the steam moves in the direction of the arrow 5, condensing on the wall surface and liquid surface of the cooling section. As a result, the liquid level in the condensing section rises, and reflux occurs in the direction of arrow 6 due to gravity.

By repeating this cycle, heat is transported as the working fluid undergoes a phase change of evaporation and condensation. However, in such a system in which a tube material having a smooth inner wall surface is used as a container and the working fluid is returned by gravity, the efficiency of condensation on the wall in the heating section is poor.

Furthermore, it is impossible to use it in so-called heat-vibe mode, where the heating part is located at a position higher than the cooling part, and the heating part tends to dry out, making it easy to lose its function as a heat pipe. There are drawbacks such as. For this reason, in a normal heat pipe, as shown in FIGS. 3 and 4, a wick 7 is provided to cover the inner wall surface of the container 1, and a working fluid 2 is provided.
It is imbued with This eliminates the above-mentioned drawbacks, but the normally used wick 7 involves attaching wire mesh or metal fibers to the inner wall surface by some method, which requires a lot of effort to assemble and increases manufacturing costs. (Also, there are drawbacks such as increased thermal resistance in the evaporation section and condensation section, and a rise in the maximum heat transport m due to the fluid resistance of the wick.

On the other hand, a groove type heat vibrator using a plurality of wicks continuous in the longitudinal direction of the container is also well known. FIG. 1 shows an example of a cross section of a container 1 having a group wick as shown in A.

In the figure, it is known that the smaller the value of the width W of group 8, the greater the capillary effect on the hydraulic fluid, and the greater the illumination that sucks up the hydraulic fluid upward against gravity. It is being However, in the case of a heat vibrator using the copper-water combination U, which is generally used in the widest range of applications, the wettability of copper water to the surface of industrially used copper is poor, and the inner wall surface of a copper container is Even if Group 8 is processed as described above, the force on the vessel will be worse than that theoretically predicted.

The reason for this is that, in many cases, a very thin oxide film is formed on the copper surface during manufacturing, increasing the contact angle between water and copper.

Therefore, the heat transport capacity of the group-type heat vibrator is small due to the weakening of the wick if the inner surface is treated for -1- minutes, and it is not possible to produce a high-performance, low-cost heat vibrator by simply installing the group. It's hard to get a vibe,
.

[Problems to be Solved by the Invention] The present invention improves the leakage of the groove surface caused by the working fluid (water), and improves the heat transfer performance. It is designed to capture and provide a unique heat vibe.

[Means for Solving Problem E] In the present invention, oxygen-free copper is used as the container material, and its 'f
The above object is achieved by forcibly forming an oxide film on the surface of the groove formed on the inner wall surface of the V vessel by chemical or thermal means.

1 work II] By forming an oxide coating on the surface of the surface (' f
The reason why wettability with liquid is improved is as follows.

For example, when pure copper is oxidized by chemical means, the surface becomes CIJzO at 1 or 11 degrees depending on the degree of oxidation.

These oxides have an irregular and thin shape, and the surface area of each oxide increases significantly compared to that of pure copper. The fine G unevenness is completely formed in the particles 11 ■, so the oxidized surface of the eel is 4! The 7J method to do this has been known for a long time [b
On OI C method, general % Q9 treatmentjL' F
i. Method of soaking in a mixture of concentrated phosphorous acid/concentrated ITI acid/water.

Weight [1 method of dissolving in sodium chloride solution (-1fi).

Various one-step methods can be used, such as flowing air or oxygen through a heated tube to avoid oxidation.

In either case, oxidize for 1 minute. (,,Cu0(
Or increase the ratio of Q LJ 20:+) L! The capillary effect will be larger if you keep CIJ Of, L-
・General (2 brittle, peeling from the surface of the base material.Especially for phosphorus-containing right forgings, if it exceeds 3pI), it will rapidly peel off, so why not use Fl as a base material? By using copper wire, it is possible to maintain the stability of the functions of 1J and (r+) over a long period of time.

1 Example J Real, outer diameter 15.9a*, low thickness JIJ! After 1.2 seconds, the groove width on the inner surface is 0. /I hazy, groove depth 0.3. An oxygen-free steel pipe with a diameter of 11 cores and a groove with a vortex number of 36 is prepared, and the inner surface of this oxygen-free steel pipe is treated with chemical treatment 1, for example, an aqueous solution of 1 to 3 hydroxides heated to about 90°C. 1. An oxide film was formed on the inner surface by an anodic oxidation method.

Next, the diagonal pipe of this chemical treatment agent was formed into a container using a conventional method, and 8 ml of pure water was added as the fl dynamic fluid to obtain a Hiba-1 Vibe with a length of 100 mm.

Comparing the heat transfer performance of the obtained heat vibrator and the vibrator 1 whose inner surface was not chemically treated, the heat transfer performance of the heat vibrator according to the present invention is improved by the formation of an oxide film. It was approved to do so.

Effects of the Invention 1 As is clear from the explanation below (S), the present invention has the advantage of providing
By forming an oxide film, the brittleness caused by the working fluid has been changed, so the chitoplic effect of the groove is increased, the heat transport properties are excellent, and the heat is stable for a long period of time. It is extremely profitable to obtain a pipe.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of an example of a groove type heat pipe, Figure 2 is a longitudinal cross-sectional view showing the function of the heat pipe, Figure 3 is its cross-sectional view, and Figure 4 is a heat pipe with a wick. A longitudinal sectional view showing no example. FIG. 5 is a cross-sectional view thereof. 1: Tubular container, 2: Working fluid, 8: Groove.兇 once

Claims (1)

[Claims] (1) In a groove type heat pipe in which a working fluid is sealed in a tubular container having a large number of thin grooves extending in the axial direction on the inner wall surface, the tubular container is made of oxygen-free copper, and the groove surface is A heat pipe characterized by the formation of an oxide film.