JPH0518623Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to devices such as heat exchangers that transport heat from a high temperature area to a low temperature area via a heat pipe.
In particular, the present invention relates to a heat pipe type heat transport device having a large heat pipe capacity.

BACKGROUND TECHNOLOGY As is well known, a heat pipe is a sealed tube in which a fluid such as water or ammonia that evaporates and condenses at a target operating temperature is sealed as a working fluid, and a capillary tube such as a wire mesh or narrow groove is used to generate pressure. It has an extremely high heat transport capacity because the working fluid flows as it evaporates and condenses and transports heat as its latent heat. Often used in heat exchangers.

By the way, a heat pipe is usually a hermetically sealed tube containing only the working fluid, so in a static state with no heat input, the working fluid inside is liquefied and is in a high vacuum state. On the other hand, when there is heat input, the internal working fluid evaporates, increasing the internal pressure. Therefore, for example, if an imbalance occurs between heat input and heat radiation, and the amount of heat input becomes larger than the amount of heat released, the internal pressure will become extremely high, and there is a risk of explosion. Heat pipes, which have particularly large diameters and can have high internal pressure, are subject to the High Pressure Gas Control Law and are treated as pressure vessels, so it is necessary to take measures to ensure safety by releasing the internal gas. required. Therefore, in order to prevent the above-mentioned dangers, for example, in Utility Model Application Publication No. 181180/1983, a thin-walled easily ruptured part is formed on the end plate that closes the open end of the heat pipe body, and this prevents the internal pressure from increasing. A structure is shown in which the easily ruptured portion is broken and opened by the rupture, thereby releasing the internal pressure. Furthermore, Japanese Patent Application Laid-open No. 51-104653 and Japanese Patent Application Laid-open No. 54-10463 disclose a structure in which the stopper is made of a metal that softens at a temperature below the service limit temperature or is bonded.

Problems that the invention aims to solve By the way, heat pipes that are large enough to be regulated by the High Pressure Gas Control Law have large main body diameters, so they are generally made with thin liquid injection pipes for injecting working fluid. is provided at the end of the main pipe section, and after injecting the working fluid, the liquid injection pipe is crushed and sealed by welding. Therefore, when using such a heat pipe in a heat exchanger, the end where the liquid injection pipe is attached should be placed on the low temperature side to prevent outside air from entering or working fluid leaking due to damage to the liquid injection pipe. The end plate on the opposite side is located on the high temperature side. However, the above-mentioned Jitsukai 58-
In the heat pipe described in Publication No. 181180, the easily ruptured part that functions as a safety device is located on the high temperature side (the evaporation side of the working fluid for a heat pipe), so the easily ruptured part is not exposed to external heat. If heat pipes are affected by heat pipes, their strength may decrease and they may no longer function as designed, or if the high-temperature source is factory waste gas, they may become corroded and may no longer function as designed. In order to facilitate heat transport, the heating section is generally installed low, so in the conventional heat pipe described above, the easily ruptured section will burst at the heating section where the working fluid accumulates. As a result, if the easily ruptured part were to rupture, there was a risk that the hydraulic fluid would be blown out along with steam.

Also, JP-A-51-104653 and JP-A-54-
In the heat pipe described in Publication No. 10463,
Since a metal with a low softening point is used at the rupture point, the rupture conditions are determined by both temperature and internal pressure, and since there is a correlation between temperature and internal pressure, the rupture pressure There were problems such as it being extremely difficult in practice to set accurately.

This idea was developed against the background of the above-mentioned circumstances, and the purpose is to provide a highly safe heat pipe type heat transport device that can accurately set the critical pressure, that is, the pressure for releasing internal steam. It is something to do.

Means for Solving the Problems In order to achieve the above object, this invention provides a thin-walled part at one end of a main pipe with a closed structure that is smaller in diameter than the main pipe and breaks open under a predetermined pressure. A heat pipe is formed by attaching a liquid injection tube formed with a liquid injection tube, and injecting a working fluid that is heated, evaporated, heat radiated, and condensed into the main pipe from the liquid injection tube to seal the liquid injection tube. The tube is installed between the high temperature section and the low temperature section so that it is located on the low temperature side of the high temperature section and low temperature section where heat should be exchanged, and at a higher position than the opposite end of the liquid injection tube. and further characterized in that a cap of a sealed structure is attached to one end of the main pipe where the liquid injection pipe is provided, surrounding the liquid injection pipe and setting the internal pressure to be lower than atmospheric pressure. be.

Furthermore, in this invention, by sealing in a non-condensable gas together with the working fluid, a variable conductance type can be achieved.

Furthermore, the liquid injection tube can be made of a material having a lower tensile strength than the main tube, or can be formed integrally with an end plate that closes one end of the main tube.

Function In the heat transport device of this invention as well, the thin walled part provided in the liquid injection pipe acts as a safety valve, which breaks and opens at a set pressure to release the internal pressure. In that case, in this invention, since the liquid injection pipe is located on the low temperature side and is hardly affected by heat, the thin walled part will break and open at the same pressure as the design pressure. In addition, since the liquid injection tube is located higher than the other end and on the low temperature side, if the thin wall part is damaged or opened,
Only working fluid vapor escapes, relieving pressure. The liquid injection tube is surrounded by a cap with a sealed structure, and the pressure inside the cap is low, so even if the thin-walled part breaks or opens and the working fluid vapor flows out from that part, the outside of the cap is closed. There is no leakage of working fluid vapor to.

On the other hand, when a variable conductance type is created by mixing a non-condensable gas, the non-condensable gas is forced into the end of the liquid injection tube during operation, and as a result,
The thin-walled part of the liquid injection tube is shielded from the working fluid vapor,
Thermal influence on thin-walled parts is further reduced.

Embodiments Next, embodiments of this invention will be described with reference to the attached drawings.

FIG. 1 is a schematic diagram showing a heat exchanger as an example of the heat transport device of this invention. It is configured so that heat exchange is performed via a heat pipe 4 provided through it. Here, the heat pipe 4 is hermetically sealed by welding end plates 6 and 7 to both ends of the main pipe 5, as shown in FIG. Non-condensable gas such as air inside is evacuated from the small-diameter liquid injection tube 8 installed, and an appropriate condensable fluid is injected as a working fluid, and then the tip of the liquid injection tube 8 is welded and sealed. This structure is provided with a wick (not shown) for stopping the main pipe 5 and generating capillary pressure inside the main pipe 5. Furthermore, a cap 14 of a sealed structure is attached to the end plate 6 of the main pipe 5 on the liquid injection tube 8 side, and the liquid injection tube 8 is surrounded by the cap 14 . Further, this cap 14 is set so that its internal pressure is a low pressure lower than atmospheric pressure. As shown in FIGS. 3 to 5, a part of the liquid injection pipe 8 has a thin-walled part 9 that serves as a safety valve that breaks and opens before the main pipe 5 ruptures when the internal pressure becomes high. is formed. In the illustrated example, this thin wall portion 9 is formed by cutting a part of the outer peripheral surface of the liquid injection tube 8 into a rectangular shape, and the concave corner portion is rounded to prevent the notch effect. ing. The processing method for this thin section 9 is as follows:
Various methods such as cutting and press working can be employed, but since there may be variations in the outer diameter of the raw tube used as the liquid injection tube 8, the thickness of the thin wall portion 9 should be made accurate. Therefore, it is preferable to perform processing based on the inner surface of the liquid injection tube 8. Further, in order to prevent variations in the breakage strength of the thin wall portion 9 due to work hardening, it is preferable to perform annealing after processing the thin wall portion 9. Furthermore, as for the material of the liquid injection pipe 8, it is preferable to use a material with low tensile strength such as aluminum, copper, or an alloy of these, in contrast to the main pipe 5 which is made of a pressure-resistant steel pipe. The tube 8 can be made thinner.

And the heat pipe 4 configured as described above
is arranged to be inclined with respect to the horizontal plane so that the liquid injection pipe 8 is on the low temperature gas side and at a higher position than the other end, and a number of fins 10 are attached to the outer peripheral surface.

In the heat exchanger described above, when high-temperature gas such as factory waste gas flows through the high-temperature gas flow path 2 and low-temperature gas such as air to be heated is flowed through the low-temperature gas flow path 3, a temperature difference is created in the heat pipe 4. As a result, the working fluid inside evaporates in the left half of FIG. 1, and the vapor flows to the right half where the liquid injection pipe 8 is provided, where it radiates heat and condenses. In other words, the left half of the heat pipe 4 in FIG. 1 serves as an evaporation section, and the right half serves as a condensation section, and the working fluid evaporates and condenses between these evaporation and condensation sections. By circulating the fluid, the heat of the high-temperature gas is transferred to the low-temperature gas as latent heat of the working fluid. During heat exchange in this way, if the temperature of the high-temperature gas increases significantly, or conversely, if the amount of heat absorbed by the low-temperature gas decreases significantly, only the heat input to the heat pipe 4 will increase. As a result, the working fluid evaporates violently, and as a result, the internal pressure of the heat pipe 4 increases. When the internal pressure of the heat pipe 4 reaches a preset dangerous pressure, the thin wall portion 9 formed in the liquid injection tube 8 breaks and opens, and the working fluid vapor flows out from there, causing the heat pipe 4 to
The internal pressure of the main pipe 5 is reduced and the bursting of the main pipe 5 is prevented. That is, the thin wall portion 9 acts as a safety valve.

By the way, in the heat exchanger described above, since the liquid injection pipe 8 forming the thin-walled part 9 is located on the low-temperature gas side and at a higher position than the end on the evaporator side, the liquid-phase working fluid flows down to the evaporator side. As a result, if the thin wall portion 9 is damaged or opened, only the working fluid vapor will be blown out, ensuring safety for the surroundings. In addition, the thin wall portion 9 is not directly affected by heat from high-temperature gas, is not exposed to a corrosive environment due to high-temperature gas, and is not affected by notch effects or work hardening due to rounding and annealing of concave corners. For reasons such as not being exposed to high pressure, the thin wall portion 9 will break and open at approximately the same pressure as the pressure assumed in the design, and in this respect as well, it will be highly safe. Furthermore, since the liquid injection tube 8 having the thin wall portion 9 is surrounded by the cap 14 having a sealed structure with a low internal pressure, if the thin wall portion 9 is damaged or opened as described above, the liquid injection tube 8 is activated from that portion. Even if the fluid vapor blows out, it is possible to prevent the working fluid vapor from flowing out to the outside of the cap 14, resulting in extremely high safety.

Note that although the liquid injection tube 8 is thin and has low strength, it protrudes from the main tube 5, so if the cap 14 is not provided, it will break if external force is applied during transportation. There is a danger, and if the thin-walled part 9 is damaged, there is a risk that its fragments will be scattered around, but by providing the cap 14, the liquid injection tube can be prevented from breaking due to external force and the fragments of the thin-walled part can be scattered. can be prevented.

Furthermore, if the working fluid vapor flows out into the cap 14, the temperature of the cap 14 will rise.
Based on the temperature of the cap 14, it is possible to detect damage or an opening in the thin wall portion 9, that is, an abnormality in the heat pipe 4.

Although the embodiment described above is an example in which only the working fluid is sealed inside the main pipe 5, the heat pipe 4 used in the heat exchanger of this invention may be of a variable conductance type. That is, FIG. 6 is a diagram showing the operating state and temperature distribution of the heat pipe 4 in which the non-condensable gas 11 is sealed in the main pipe 5 together with the working fluid. However, since the non-condensable gas 11 is forced into the condensing part side during operation, the non-condensable gas 11
acts as a thermal shield for the thin wall portion 9, and as a result, the thermal influence on the thin wall portion 9 is further reduced. In other words, the thin walled portion 9 acts as a safety valve.
The pressure at which the valve breaks or opens is closer to the design pressure, increasing safety.

FIG. 7 is a schematic diagram showing still another example of the heat pipe 4 used in this invention, in which the liquid injection pipe 8 and the end plate 6 are integrally formed in advance, and the end plate 6 is attached to the main pipe 5. It is welded. With such a configuration, the pressure at which the thin wall portion 9 breaks or opens can be made constant. In other words, the thin wall portion 9 is processed before the liquid injection tube 8 is attached to the end plate 6 or the main pipe 5 due to processing constraints.
If the end plates 6 and 6 are separate bodies, there is a risk that the heat effect when welding them will affect the thin walled part 9 and cause variations in its strength. However, in the configuration shown in FIG. 7, the end plate 6
Thermal influence during welding does not affect the thin wall portion 9, and as a result, the damage and opening pressure of the thin wall portion 9 can be made constant.
In addition, in the structure shown in FIG. 7, the strength of the end plate 6 is improved and the number of welded parts is reduced, so that the occurrence of defective products is reduced.

Note that in this invention, the thin wall portion 9 is not limited to being formed into a rectangular shape as described above, but may be formed by cutting grooves into a U-shape as shown in FIGS. 8 and 9, for example. , the tongue piece 15 may be formed.

Furthermore, the device of this invention can be used as long as it transports heat when exchanging heat between a high-temperature part and a low-temperature part, as shown in the above embodiment. In addition to heat exchangers for heat recovery, it can also be applied to equipment for extracting geothermal heat, heat transport equipment for snow melting, etc.

Effects of the invention As explained above, in the heat transport device of this invention, the heat pipe is installed so that the liquid injection pipe provided with the thin-walled part that serves as a safety valve is on the low-temperature part side and higher than the other end. As a result, the thin-walled parts break and open at the pressure assumed in the design, increasing safety.Also, the liquid-phase working fluid on the liquid injection pipe side is extremely low. This prevents the hydraulic fluid from spouting out, and since the fluid injection pipe is surrounded by a cap with a low-pressure hermetic structure, there is no possibility that the thin-walled part will break or open and the working fluid vapor will flow out from that part. In addition to preventing the working fluid vapor from leaking to the outside of the cap, it also prevents breakage of the liquid injection tube, which is a thin tube, and prevents fragments from scattering when the thin wall part is damaged. can be prevented and is therefore extremely safe overall.

Furthermore, if the heat pipe is of a variable conductance type that contains non-condensable gas, the non-condensable gas acts as a thermal shield for the thin-walled parts during operation, reducing the thermal effect on the thin-walled parts. This makes it possible to stabilize the failure pressure and improve safety.

Furthermore, if the liquid injection tube and the end plate are integrally molded in advance, the heat effect when welding the end plate will not affect the thin wall part, so the failure pressure of the thin wall part will be constant and safety will be increased. be able to.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing one embodiment of this invention, Fig. 2 is a schematic sectional view showing an example of the heat pipe, Fig. 3 is a partial view showing the liquid injection pipe, and Fig. 4 is a schematic sectional view showing an example of the heat pipe.
The figure is a view taken along the - line in Fig. 3, Fig. 5 is a view taken along the - line in Fig. 3, Fig. 6 is a view showing the operating state of the variable conductance type heat pipe and its temperature distribution, and Fig. 7 The figure is a partial view of a heat pipe in which a liquid injection tube and an end plate are integrated, FIG. 8 is a partial view showing another example of a thin walled portion, and FIG. 9 is a view taken along the - line in FIG. 1... Partition wall, 2... High temperature gas flow path, 3... Low temperature gas flow path, 4... Heat pipe, 5... Main pipe,
6, 7... End plate, 8... Liquid injection pipe, 9... Thin wall part, 11... Non-condensable gas, 12... Exhaust hole, 1
3,14...cap.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) At one end of a main pipe with a sealed structure, a liquid injection pipe having a diameter smaller than that of the main pipe and forming a thin walled part that breaks open under a predetermined pressure is attached and heated. A heat pipe is formed by injecting a working fluid that evaporates, radiates heat, and condenses from the liquid injection pipe into the main pipe, and seals the liquid injection pipe, between the high temperature part and the low temperature part where the liquid injection pipe should exchange heat. The liquid injection pipe is installed between the high temperature part and the low temperature part so as to be located on the low temperature side of the main pipe and at a higher position than the end on the opposite side to the liquid injection pipe. 1. A heat pipe type heat transport device with a safety device, characterized in that a cap with a sealed structure that surrounds a liquid injection pipe and is set at an internal pressure lower than atmospheric pressure is attached to one end side of the heat pipe. (2) The safety device according to claim 1 of the utility model registration claim, characterized in that a non-condensable gas that does not condense in the working temperature range is sealed inside the main pipe together with the working fluid. Heat pipe type heat transport device. (3) The heat pipe heat pipe with a safety device according to claim 1, wherein the liquid injection pipe is made of a material having a lower tensile strength than the material constituting the main pipe. transport equipment. (4) A safety device according to claim 1 of the utility model registration claim, characterized in that the liquid injection pipe is integrally formed with an end plate that seals one end of the main pipe. Heat pipe type heat transport device.