JPS6051034B2 - Heat pipe with fins - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure of a finned heat pipe with increased heat transport capacity.

A heat pipe is a heat transfer element that creates a vacuum in a closed container and seals a working medium with desired characteristics in it, and transports heat by utilizing the phase change of the working medium, that is, the latent heat during boiling vaporization and condensation. In order to further improve the heat transfer efficiency of this heat pipe, a heat pipe with fins has been provided, but this conventional finned heat pipe also has some drawbacks.

To explain this based on the drawings, FIG. 1 shows a case where a conventional finned heat pipe is used as a gas-to-gas heat exchanger. Fins 2 are attached to the outer periphery of the heat pipe 1 at equal intervals, and a working medium 3 is sealed inside. This heat pipe 1 is installed in channels 6 and 7 separated by a partition plate 5, and high temperature gas such as undenitrated exhaust gas is fed into the channel 7.
When low-temperature gas is flowed through each of the flow paths 6, the working medium 3 in the heat pipe 1 is
receives heat and evaporates, becoming steam 4. This evaporation 4 flows toward the low-temperature gas flow path 6, which is a cooling section, and condenses to release latent heat. The condensed working medium 3 is transferred to the heat pipe 1
It returns to the heating section and evaporates again due to the capillary force caused by the porous material inside or by gravity, and by continuing this action, heat is transferred to the cooling section. Therefore, in order to operate the heat pipe stably and efficiently, it is necessary to return the working medium 3 to the heating section without interruption. However, in conventional finned heat pipes, the fins are installed at equal intervals, so as the temperature difference between high temperature gas and low temperature gas increases: The closer the heat pipe is to the partition plate 5, the larger the surface heat flux becomes, and as a result, the closer it gets to the end of the heat pipe, the less effective the heat pipe becomes, and in the worst case, dry-out occurs, significantly reducing heat transfer efficiency. This will be explained using FIGS. 3 and 4, which show experimental results using a conventional finned heat pipe having a length of 3 wL. FIG. 3 shows the results of examining the amount of heat transport by varying the temperature difference ΔT between the high-temperature gas and the low-temperature gas.
Figure 4 shows the distribution of heat flux in the axial direction of the heat pipe.
On the horizontal axis, 0 indicates the center of the heat pipe, -1 indicates the end of the cooling section, and +1 indicates the end of the heating section. In Fig. 3, curve 8 is a measurement of the amount of heat transport Q when the temperature difference ΔT between high temperature gas and low temperature gas is increased using a conventional finned heat vibrator, and the temperature difference ΔT1
The amount of heat transported decreases as the temperature difference increases. The axial heat flux distribution when the temperature difference ΔT1 is indicated by line 10 in FIG. 4, and it can be seen that it is almost constant. However, when the temperature difference is ΔT2, the heat flux distribution in the axial direction is extremely large in the part of the heating section near the partition plate 5, as shown by line 11 in FIG. It decreases rapidly and reaches almost 0 at the end.
This means that a dry-out phenomenon occurred at the end of the heating section, indicating that the heat transfer ability of the heat vibrator was significantly reduced. As described above, the conventional finned heat vibrator has the disadvantage that when the temperature difference exceeds a certain limit, a dry-out phenomenon occurs, resulting in a significant drop in performance. SUMMARY OF THE INVENTION An object of the present invention is to provide a heat pipe with fins that eliminates the drawbacks of the prior art described above and has improved heat transport ability.

In short, the present invention focuses on the fact that the cause of the significant decrease in the heat transport amount of the heat vibrator is that the heat flux increases in the part of the heating section near the partition plate, and the dry-out phenomenon occurs outside of that part. As a means to prevent the dry two-out phenomenon from occurring, the fin mounting density is reduced in areas where the heat flux is large.

Next, embodiments of the present invention will be described based on the drawings.

In FIG. 2, the fins 2 of the finned heat pipe 3 of the present invention are arranged so that they become gradually coarser toward the partition plate penetrating portion of the heat vibrator 1, that is, toward the center. In this arrangement, the mounting density of the fins in the center is 11? It is good when used in moderation. others,
Heatby 3. The structure inside the pulley is the same as the conventional finned heating element described above.
It is similar to the martial arts pipe. According to the present invention, the heat flux in the portion of the heating section near the partition plate is reduced, and it is possible to prevent the dryout phenomenon from occurring at the end of the heating section and in the vicinity of the end. Even if the difference becomes large, there is no significant decrease in the amount of heat transport, and the amount of heat transport can be increased compared to the conventional heat vibrator with fins.

This is specifically shown in FIGS. 3 and 4.
3rn and 4) according to the present invention,
The results of an experiment using a heat vibrator with fins are shown, and curve 9 in FIG.
These are the results of measuring the amount of heat transported from the heating side to the cooling side. According to this, it can be seen that even when the temperature difference becomes ΔT2, the peak of the heat transport amount does not appear, and the heat transport amount increases. The heat flux distribution in the axial direction of the heat vibrator in this case is as shown by curve 12 in FIG. 4, which shows that no dryout phenomenon occurs and the heat flux is maintained almost equal in the axial direction. By implementing the present invention, it is possible to prevent dryout within the heat vibrator and to efficiently transfer a large amount of heat.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the structure of a conventional finned heat vibrator, Fig. 2 is a sectional view showing the structure of a finned heat vibrator of the present invention, and Fig. 3 is a sectional view of the conventional finned heat vibrator and the fin of the present invention. Figure 4 is a graph showing the heat flux distribution in the axial direction of the heat vibrator with double fins, with temperature difference on the horizontal axis and heat transport on the vertical axis. The axial direction is shown on the axis, and the heat flux on the vertical axis is shown.

Claims (1)

[Scope of Claims] 1. A heat pipe with fins, characterized in that the arrangement density of the fins provided on the heat pipe becomes coarser as they get closer to the partition plate through which the heat pipe passes. 2. The finned heat pipe according to claim 1, wherein the arrangement density of the fins near the partition plate penetration portion of the heat pipe is set to 1/3 of the arrangement density of the fins at both ends.