JPH0151760B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a gravity type heat pipe in which a part of the heat collecting part (heating part) is heated by light irradiation, hot air, or a heating element such as a heater, thereby reducing the temperature of the working fluid sealed in the heat pipe. This makes it possible to estimate the amount of non-condensable gas mixed in with simple equipment in a short time, and it is possible to very easily judge whether the characteristics of a heat pipe are good or bad.

Fig. 1 shows a general gravity heat pipe 1, which is composed of a heating section A, a heat insulating section B, and a condensing section C. Structurally, a working fluid 3 is sealed in a container 2, and as needed. Attach heat collecting fins 4 and heat dissipating fins 5 accordingly. In this gravity heat pipe, when the heating section A is heated, the heat is collected by the heat collection fins 4 and transferred to the working fluid 3. When the working fluid 3 is heated, it absorbs latent heat and evaporates, reaching the condensing section C, where it releases latent heat and becomes liquefied, and flows back to the heating section A through the pipe wall. In this way, the heat obtained in the heating section A is efficiently transferred to the condensing section C and released to the outside. In such a gravity type heat pipe, if the amount of the working fluid 3 sealed is small and all of the working fluid 3 evaporates due to heating, the added heat cannot be efficiently transferred to the condensing section C. That is, the amount of heat conveyed decreases, and in some cases, the heating portion A becomes abnormally high in temperature (same level as the heating temperature), leading to damage to the heat pipe 1. Therefore, if the amount of the working fluid 3 is increased more than necessary, it will take time for the working fluid 3 to reach the evaporation temperature, leading to a decrease in heat transfer characteristics and increasing costs due to the use of the extra working fluid 3.

Furthermore, when non-condensable gas is mixed into the inside of the heat pipe 1, this gas accumulates at the tip of the condensing section C and acts to prevent the vapor of the working fluid 3 from reaching the tip of the condensing section C. . Therefore, the effective surface area of the condensing section C is reduced due to the occupation of this non-condensable gas, reducing the heat exchange rate. As mentioned above, the factors that affect the characteristics of the gravity heat pipe include the amount of hydraulic fluid 3 and the amount of non-condensable gas mixed in, and by controlling these values, the characteristics of the gravity heat pipe can also be managed. can do. However, since the container 2 of the heat pipe 1 is generally opaque (tempered glass or transparent plastic may be used in some cases), the amount enclosed cannot be measured from the outside. Furthermore, since the non-condensable gas is generally air, it is impossible to measure its incorporation from the outside.

Therefore, as a method for measuring the characteristics of a gravity heat pipe, conventionally, the heating part A of the heat pipe 1 is
A method has been used to estimate the degree of contamination of non-condensable gas by soaking in hot water and measuring the temperature difference between the lower end and the upper end of the condensing section C. In order to measure the amount of heat transfer, the heating section A was immersed in hot water, and after the system reached a thermal equilibrium state, the amount of heat released from the condensing section C was measured to determine the amount of heat transfer. In this case, if the gravity heat pipe is small and has a simple structure, the inspection equipment is simple and easy to handle, but if the gravity heat pipe is large and has a complicated shape, large inspection equipment is required and handling becomes difficult. It will be inconvenient. Furthermore, when measuring heat transport, it takes time to reach thermal equilibrium, and when immersing in hot water, the container 2
Depending on the material used, prevention of rust must also be considered, and this is not a desirable method for industrial testing.

The present invention eliminates the above drawbacks and makes it possible to easily and quickly test the characteristics of gravity heat pipes of any shape. That is, as shown in FIG. 2, this is a method in which a part of the heating section A is heated. In the figure, 6 is a heating source such as light irradiation, hot air, or an electric heater, and 7 is a liquid level 8, 9, and 10 on the upper surface of the working fluid 3, which is a temperature measurement device for measuring the temperature of the outer surface of the container 2 of the heat pipe 1. Department. Now, when the heating source 6' is placed above the liquid level 7 of the working fluid 3 and the heat pipe 1 is heated, the temperatures T of the temperature measuring parts 8', 9, and 10 will change over time as shown in FIG. make a change. That is, in the temperature measuring section 8' located near the heating section by the heating source 6', the temperature rises rapidly because the container 2 is heated. In the temperature measuring section 9 at the lower end of the condensing section C and the temperature measuring section 10 at the upper end, since the heating source 6' is above the liquid level 7,
Since the working fluid 3 is not heated, the vapor of the working fluid 3 does not reach the system. Therefore, the temperature does not rise as shown in FIG. However, the heating source 6'' is lower than the liquid level 7 of the working fluid 3.
If it is nearby, the working fluid 3 will be heated and evaporated in a short time. At this time, the latent heat of vaporization is taken away from the surroundings, so the temperature of the temperature measuring section 8'' near the heating section does not rise much as shown in Figure 4.
The temperature measuring sections 9 and 10 at the lower end and the upper end are heated by the vapor of the working fluid 3, so that the temperature increases as shown in FIG. 4. In this way, the hydraulic fluid 3
The liquid level can be estimated. Since there is a substantially constant relationship between the designed amount of the working fluid 3 and the amount of heat transfer, the amount of heat transfer can also be inferred and an outline of the characteristics of the gravity heat pipe can be grasped. Further, when there is no non-condensable gas, there is almost no temperature difference between the upper and lower ends of the condensing section C. Therefore, if there is a temperature difference between the upper and lower ends of the condensing section C, it can be assumed that non-condensable gas is mixed in. Practically, the designed liquid management surface of the container 2 is heated, and after a certain period of time (usually several minutes), for example, as shown in FIG.
By measuring the temperature rise in the temperature measurement parts 9 and 10 _one hour after t in Fig. 4, it is possible to determine whether there is a liquid level in the heating part and whether non-condensable gas is mixed in. I can do it. The heating source may be light irradiation, hot air, a heater, or the like, but light irradiation is simple and practical.

As described above, the present invention uses a heating element to heat only the vicinity of the designed working fluid surface in the heat collecting section of a gravity heat pipe, and also measures the temperature of the vicinity of the liquid surface and the lower and upper ends of the condensing section. Therefore, the amount of working fluid sealed in the heat pipe and the mixture of non-condensable gas can be easily determined in a short time and with simple equipment.

In addition, since only the area near the surface of the working fluid in the heat pipe is heated by the heating element, the temperature measuring section can accurately measure the temperature depending on whether the working fluid is heated or not and whether steam is generated. can be determined accurately and quickly, and is economical as it requires less thermal energy than conventional technology that heats the entire working fluid of the heat pipe.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a gravity type heat pipe, FIG. 2 is a sectional view of a gravity type heat pipe showing an inspection method according to an embodiment of the present invention, and FIGS.
FIG. 3 is a characteristic diagram showing a change over time in temperature rise of a gravity heat pipe when measured by the method shown in the figure. 1... Gravity type heat pipe, A... Heat collecting section,
6, 6', 6''...Heating source.

Claims (1)

[Claims] 1 A gravity type heat pipe characterized by heating only the vicinity of the designed working fluid surface in the heat collecting section of the gravity heat pipe with a heating element, and measuring the temperature near the liquid surface and the lower and upper ends of the condensing section. Method for testing heat pipe characteristics.