JPS5833428Y2 - heat pipe - Google Patents

Description

[Detailed description of the invention] This invention uses ordinary carbon steel, stainless steel, etc. as the heat pipe component, and a palladium wire or palladium-silver (5 to 50%) alloy wire is attached to the condensation part of the container of this component. This invention relates to an improved heat pipe formed by inserting a heat pipe, and aims to improve performance in a low temperature range of less than 130°C.

As is well known, a heat pipe is a system in which a condensable liquid (working fluid) is sealed in a sealed vacuum container, and the liquid is evaporated and condensed at different locations in the container to reduce heat propagation due to the latent heat of the working fluid. It is something you can do.

Water as a working fluid has a latent heat of vaporization (546 cal/g
), which is considered to be the best in terms of critical heat flow (109 W/crn2).

However, in a heat pipe that uses water as a working fluid, when carbon steel, stainless steel, or the like is used as a constituent material of the heat pipe, the constituent material reacts with water to generate hydrogen gas.

This generated hydrogen gas is forced into the steam of the working water and has the drawback of reducing the effective length of the reservoir reheat pipe in the condensing section and reducing the amount of heat transferred.

In order to eliminate these drawbacks and make it practical,
The inventors of the present invention have submitted the application No. 52-052722.
-142 Publication), "Palladium wire or palladium wire or
He proposed a heat pipe with a silver (5-50%) alloy wire inserted.

According to this heat pipe, the effective length of the heat pipe can be maintained at all times by passing the hydrogen gas flowing into the working fluid condensation area through the palladium wire and its alloy wire inserted above and discharging it. It became possible.

However, this proposed heat pipe has a temperature of 130℃
When used at a temperature above 100°F, it can be used extremely effectively and brings about two benefits in practical use. With palladium wire or its alloy wire (0.5 to 1 mmφ), it is not possible to sufficiently extract the hydrogen gas flowing into the condensation area, and the performance will be lower than when used at high temperatures of 130°C or higher. was recognized.

The reason for this is thought to be due to the hydrogen gas pressure inside the heat pipe.

Another problem is that corrosion of the heat pipe constituent materials progresses more than expected even at the lower temperatures.

Therefore, it is natural to consider measures to improve the disadvantages when used at low temperatures as described above, such as increasing the wire diameter of palladium wire or its alloy wire, increasing the number of wires, and condensing with palladium or its alloy. One possible solution is to construct a part of the heat pipe, but if we consider reducing the production cost of the heat pipe, it is clear that the cost will be high industrially and it will not be profitable.

Therefore, based on the viewpoint that it is desirable to suppress corrosion of heat pipe constituent materials so that hydrogen gas permeation can be achieved satisfactorily even if the wire diameter of the palladium wire or its alloy wire is as thin as 1 mm, various methods have been proposed. As a result of exploration and prototyping, we arrived at the idea of sealing a chromate aqueous liquid as the working fluid in the heat pipe.

FIG. 1 shows the heat pipe of the present invention which has been embodied as described above.

In the figure, 1 indicates a closed cylindrical container, 2 indicates a wick,
A working fluid 3, which is an aqueous chromate solution, is sealed in a sealed cylindrical container, and a palladium wire 4 is inserted into the side end of the container 1, looking into the gas tank H of the condensing section C of this container. The structure is as follows.

The symbol ■ in the figure indicates the evaporation section.

The hydraulic fluid that is the source of the effects of the present invention will be described.

Corrosion of iron by water is generally calculated by the following formula: Fe+2 H2O,l! Fe(OH)z+H2(1) ferrous hydroxide is produced.

This is 3Fe(OH)22Fe304+2H20+H2(2) according to the following formula.
Magnetite is produced, which creates a protective layer.

This magnetite is known to have stable protective properties on the alkaline side with a pH of 10 to 11, and it is well known that water with a stable pH range is used in boilers.

It is conceivable to adjust the working water to this range (by adding sodium hydroxide, amines, and sodium phosphate) according to this stable PH range (PH10-11: Fe304), but the test examples described below will show this. low temperature range (7
(0 to less than 130°C), it does not show good heat pipe performance.

Therefore, the present inventors believe that if the pH value of the water used as the working fluid is kept within a stable range, the transition reaction of ferrous hydroxide to magnetite shown in the above reaction formula (2) will be slow in the low temperature range, so corrosion protection will be prevented. As a result of conducting tests based on the fact that it was confirmed that good results could not be obtained due to insufficient formation of the layer, it was found that by adding chromate (e.g. sodium chromate aqueous solution), hydroxide oxidation was improved even at low temperatures. It exhibits a catalytic effect that promotes the transition reaction of ferrous iron to magnetite, and also effectively forms a protective layer on the surface of the heat pipe component, and the palladium wire or its alloy wire is attached to the condensation area in the heat pipe component container. This makes it possible to completely prevent performance degradation on the low temperature side of the inserted H-I pipe.

Below, we will show test examples of the present invention to clarify its effects.

Test example I JIS STKM pipe (carbon steel pipe for mechanical structure) outer diameter 1
A container with a diameter of 6 mm, a wall thickness of 2 mm, and a length of 800 mm was selected, and the following hydraulic fluids were used in a container equipped with a 160 mesh wick made of SUS 304. A palladium wire with a diameter of 1 mm was inserted in the center of one end surface.

Working fluid (I) A 0.05% sodium chromate aqueous solution prepared by adding sodium chromate to water (distilled water).

(II) Water whose pH was adjusted to 11 by adding NaOH.

Each working fluid filled 10% of the internal volume of the heat pipe.

The evaporation section of each heat pipe was heated to a level of 70 DEG C., and the tube wall temperature was measured at measurement points 1' to 7' as shown in FIG. 2, and the temperature distribution is shown in FIG.

In addition, the distance (mm) of the measurement points is also shown in FIG.

According to the test results, it was found that the working water with the addition of chromate allows the heat pipe to exhibit sufficient performance even at low temperatures.

Test Example 2 Test 1 was conducted in the same manner as in Test Example 1, but the evaporation section was heated to a level of 120° C. The results of Test 1 are shown in FIG. 4.

As can be seen from these results, it is clear that the effect of the hydraulic fluid (I) described in Test Example 1 is significant.

Test Example 3 When a heat pipe containing the following working fluid was tested at 70°C under the same material, structure, and flow rate conditions as Test Example 1, as shown in Figure 5, a sodium chromate aqueous solution was tested. showed remarkable effects when used as the working fluid.

According to the heater of this invention, the water heat pipe is made of carbon steel,
Since it can be made of stainless steel or the like, manufacturing costs can be significantly reduced compared to conventional constituent materials of copper and its alloys.

Furthermore, it can be used in a low temperature range of 70 to less than 130°C, and has the advantage of maintaining performance even during long-term use.

[Brief explanation of drawings]

Figure 1 shows the constituent countries of the heat pipe of the present invention, Figure 2 is an explanatory diagram showing the positions of measurement points in test examples of the heat pipe of the present invention, and Figures 3, 4, and 5 show the test results. This is a chart showing.

Claims (1)

[Scope of utility model registration request] A heat pipe in which a palladium wire or a palladium-silver alloy wire is inserted into the working fluid condensation part of the heat pipe, and a chromate aqueous liquid is sealed as the working fluid.