Heat pipe

Abstract

To provide a heat pipe that improves heat transport capacity, enables highly efficient heat transport of large quantities without power consumption, and is structurally easy to scale up. [Solution] A loop-shaped heat pipe 1 having a liquid phase section 4 in which the inside is under negative pressure and liquid working fluid is stored at the bottom, comprising: a first pipe section 2 extending in the vertical direction; a second pipe section 3 extending in the vertical direction with its upper and lower ends communicating with the upper and lower ends of the first pipe section 2, respectively; an evaporator 5 located in the lower part of the first pipe section 2 that evaporates the working fluid in the liquid phase section 4; a condenser 6 interposed above the liquid surface of the liquid phase section 4 in the second pipe section 3 that condenses the vapor V of the working fluid evaporated by the evaporator 5; a liquid collection section 7 that collects the working fluid condensed and liquefied in the condenser 6 and drops it into the liquid phase section 4 of the second pipe section 3; and a bypass pipe 8 having one end opening between the condenser 6 and the liquid collection section 7 and the other end opening into the second pipe section 3 between the liquid collection section 7 and the liquid phase section 4.

Description

Technical Field

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[0001] The present invention relates to a heat pipe that transports thermal energy from a low-temperature heat source such as warm water.

Background Art

[0002] Conventionally, in factory production equipment and the like, various types of heat, including boiler steam, are utilized in various processes. However, much of the waste heat has been discharged as warm wastewater or the like without being utilized. In addition, the heat absorbed by the circulating water used for equipment cooling has also been released into the atmosphere by cooling towers or the like and thus has not been utilized.

[0003] In theory, it is also possible to use a heat pipe for recovering low-temperature waste heat. For example, a heat pipe using a wick (Patent Document 1, etc.) has been proposed. However, due to the limitation that the reflux of the working fluid in the heat pipe using a wick is due to the capillary phenomenon of the wick, a large amount of thermal energy cannot be transported.

[0004] Therefore, a two-phase circulation type loop heat pipe (Patent Document 2, etc.) that circulates a two-phase mixed fluid of gas and liquid without using a wick is known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, conventional two-phase circulating loop-type heat pipes that do not use wicks rely on the sensible heat of the working fluid circulating through bubbles for heat transport. Compared to systems that utilize the latent heat of vaporization of the working fluid, the amount of heat transported is poor, and a large amount of working fluid is required to transport a large amount of heat.

[0007] Therefore, the main objective of the present invention is to provide a heat pipe that enables high-capacity heat transport with a small amount of working fluid compared to conventional heat pipes. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a loop-shaped heat pipe having a liquid phase portion in which a liquid working fluid is stored at the bottom and the inside is under negative pressure, comprising: a first pipe portion extending in the vertical direction; a second pipe portion extending in the vertical direction and whose upper and lower ends communicate with the upper and lower ends of the first pipe portion, respectively; an evaporator located below the first pipe portion that evaporates the working fluid in the liquid phase portion; a condenser interposed above the liquid surface of the liquid phase portion of the second pipe portion that condenses the vapor of the working fluid evaporated by the evaporator; a liquid collection portion that collects the working fluid condensed and liquefied in the condenser and drops it into the liquid phase portion of the second pipe portion; and a bypass pipe having one end opening into the second pipe portion between the condenser and the liquid collection portion and the other end opening into the second pipe portion between the liquid collection portion and the liquid phase portion.

[0009] Preferably, the system further includes an overflow pipe that allows the working fluid of the liquid collected in the liquid collection section to overflow from a predetermined liquid level in the liquid collection section and flow between the liquid collection section and the liquid phase section. [Effects of the Invention]

[0010] According to the present invention, the working fluid in the liquid phase is heated in the evaporator, vaporizes, rises as steam, diffuses from the first pipe section to the condenser in the second pipe section, condenses in the condenser, falls back into the liquid phase section 4, and the working fluid is circulated by the energy of this fall. In other words, instead of circulating sensible heat by bubbles as in conventional two-phase circulating heat pipes, the working fluid heated in the evaporator is transported as latent heat, which is greater than the sensible heat. The driving force for circulation is the energy of the fall from the condenser to the liquid phase section, and since steam (latent heat) is used for heat transport, it is possible to transport a large amount of heat with high efficiency and without power, compared to conventional heat pipes that return condensate generated in the heat dissipation section to the heat receiving section by the capillary action of the wick, and two-phase circulating heat pipes that use the sensible heat of the working fluid for heat transport. [Brief explanation of the drawing]

[0011] [Figure 1] This is a longitudinal cross-sectional view showing one embodiment of the heat pipe according to the present invention. [Modes for carrying out the invention]

[0012] An embodiment of the heat pipe according to the present invention will be described below with reference to the drawings. Referring to Figure 1, the heat pipe 1 is loop-shaped and has a liquid phase portion at the bottom where a liquid working fluid is stored, and comprises a first pipe section 2 extending in the vertical direction, a second pipe section 3 extending in the vertical direction with its upper and lower ends communicating with the upper and lower ends of the first pipe section 2, respectively, an evaporator 5 at the lower part of the first pipe section 2 that evaporates the working fluid in the liquid phase portion 4, a condenser 6 interposed above the liquid surface of the liquid phase portion 4 in the second pipe section 3 that condenses the vapor of the working fluid evaporated by the evaporator 5, a liquid collection section 7 that collects the working fluid condensed and liquefied in the condenser 6 and drops it into the liquid phase portion 4 of the second pipe section 3, and a bypass pipe 8 with one end opening into the second pipe section 3 between the condenser 6 and the liquid collection section 7 and the other end opening into the second pipe section 3 between the liquid collection section 7 and the liquid phase portion 4.

[0013] Figure 1 illustrates a loop-shaped heat pipe 1 in which a first pipe section 2 and a second pipe section 3 are connected at their upper and lower ends by upper and lower horizontal connecting sections 9 and 10. The loop shape of the heat pipe 1 is not limited to the illustrated example; it may be elliptical or other shapes. The inside of the heat pipe 1 is sealed by pre-vacuuming and creating negative pressure, but the internal pressure can be reduced when necessary by connecting a vacuum pump.

[0014] An evaporator 11 is interposed in the first pipe section 2, and a portion of the working fluid from the liquid phase section 4 enters the evaporator 11 up to a predetermined level. The evaporator 5 heats and evaporates the working fluid in the liquid phase section 4 within the evaporator 11. In the illustrated example, the evaporator 5 is equipped with a supply port 5a for supplying a heat transfer medium 12H for heat exchange with the liquid working fluid in the evaporator 11, and a discharge port 5b for discharging the heat transfer medium 12L after heat exchange. The heat transfer medium 12H supplied from outside the evaporator 5 to the supply port 5a heats the working fluid in the liquid phase section 4 within the evaporator 11, generating vapor V of the working fluid. The working fluid in the liquid phase section 4 is, for example, water, and the heat transfer medium 12H supplied to the supply port 5a is, for example, warm wastewater at 50-60°C. The heat transfer medium 12H can be any fluid that can heat the working fluid in the liquid phase section 4 within the evaporator 11 and bring it to a low-temperature boil under reduced pressure. The heat transfer medium 12L, which has been cooled by heat exchange with the working fluid, is discharged from the outlet 5b of the evaporator 5.

[0015] The vapor of the working fluid evaporated in the evaporator 11 rises through the first pipe section 2, diffuses from the upper connecting section 9 to the condenser 6 in the second pipe section 3, where it is condensed (cooled) and separated into liquid (condensed water) and gas (vapor that did not condense).

[0016] The condenser 6 has a supply port 6a through which a refrigerant 13L is supplied to cool the working fluid vapor, and a discharge port 6b through which the refrigerant 13H, after cooling the working fluid vapor V, is discharged. The refrigerant 13L can be any fluid that can cool the working fluid vapor V, for example, water at 20-30°C. The refrigerant 13H heated in the condenser 6 is discharged from the discharge port 6b. In this way, heat from the heat transfer medium 12H is transferred to the refrigerant 13H by the heat pipe 1. In the illustrated example, a boiler 14 is interposed in the second pipe section 3, and the condenser 6 is disposed inside the boiler 14.

[0017] The working fluid condensed in the condenser 6 is collected in a liquid collection section 7 located at the bottom of the condenser 6. In the illustrated example, the liquid collection section 7 is located at the bottom of the boiler body 14. Within the boiler body 14, a space S1 is provided between the condenser 6 and the liquid collection section 7. The liquid collection section 7 is equipped with a drain port 7a at its bottom. As shown in the illustrated example, the drain port 7a is cylindrical, extending downward from the bottom of the liquid collection section 7, so that the vector of the falling working fluid is aligned. The amount of working fluid (liquid) flowing through the drain port 7a per unit time is set to be less than the amount of working fluid condensed and liquefied per unit time in the condenser 6. As a result, working fluid (condensed liquid) accumulates in the liquid collection section 7, and the working fluid accumulated in the liquid collection section 7 is discharged all at once from the drain port 7a and falls into the liquid phase section 4 below the second pipe section 3. The falling energy of the working fluid discharged from the drain port 7a creates a downward flow in the liquid phase section 4 of the second pipe section 3, quickly moving the working fluid in the liquid phase section 4 to the first pipe section 2.

[0018] The bypass pipe 8 connects the space S1 between the condenser 6 and the liquid collection section 7 with the space S2 (space within the second pipe section 3) between the liquid collection section 7 and the liquid phase section 4 of the second pipe section 3. Therefore, even if the working fluid liquefied in the condenser 6 is stored in the liquid collection section 7 and the drain port 7a is blocked by the working fluid, the bypass pipe 8 prevents a pressure difference from occurring between space S1 and space S2. This prevents a height difference from occurring between the liquid level 4a of the liquid phase section 4 in the evaporator 11 interposed in the first pipe section 2 and the liquid level 4b of the liquid phase section 4 in the second pipe section 3, thus preventing obstruction of the movement and circulation of the working fluid. In other words, the reduction in the working fluid in the liquid phase 4 due to evaporation by the evaporator 5 in the evaporator 11 interposed in the first pipe section 2 is compensated for by the fact that the pressures in spaces S1 and S2 are kept nearly uniform. Therefore, in order to eliminate the height difference between the liquid level 4a in the liquid phase 4 inside the evaporator 11 and the liquid level 4b in the liquid phase 4 inside the second pipe section 3, the working fluid (condensed water) that falls from the liquid collection section 7 into the second pipe section 3 is quickly recirculated towards the liquid level 4a in the evaporator 11.

[0019] The heat pipe 1 further includes an overflow pipe 15 that allows the working fluid (condensed water) collected in the liquid collection section 7 to overflow from a predetermined liquid level in the liquid collection section 7 and flow between the liquid collection section 7 and the liquid phase section 4. When the liquefaction of the vapor V in the condenser 6 progresses and the liquid level 7b in the liquid collection section 7 rises, the working fluid (condensed water) in the liquid collection section 7 is discharged through the overflow pipe 15 to the liquid phase section 4 of the second pipe section 3, thereby maintaining the liquid level 7b in the liquid collection section 7 at a predetermined level. This prevents the working fluid (condensed water) in the liquid collection section 7 from overflowing into the bypass pipe 8 and blocking it. Alternatively, the bypass pipe 8 may be configured to also carry the working fluid (condensed water) that has risen in the liquid collection section 7, so that the bypass pipe 8 also functions as the overflow pipe 15.

[0020] According to the heat pipe 1 having the above structure, the working fluid in the liquid phase part 4 is heated in the evaporator 5 to become vapor V and rises, is condensed in the condenser 6, and falls into the liquid phase part 4, and the working fluid is circulated by the falling energy. That is, instead of circulating sensible heat by bubbles like a conventional two-phase circulation type heat pipe, the working fluid heated in the evaporator 5 is vaporized and heat is transported as latent heat larger than sensible heat. Since steam (latent heat) is used for heat transport, the heat transport amount is more likely to be enlarged in structure compared with a conventional heat pipe driven by the capillary phenomenon of the wick or a two-phase circulation type heat pipe using sensible heat, and a large amount of heat can be transported highly efficiently without power.

[0021] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the evaporator and the condenser are not limited to the illustrated examples, and may have a structure capable of evaporating and condensing the working fluid in the heat pipe 1.

Explanation of Reference Numerals

[0022] 1 Heat pipe 2 First pipe part 3 Second pipe part 4 Liquid phase part 5 Evaporator 6 Condenser 7 Liquid collection part 8 Bypass pipe 15 Overflow pipe

Claims

1. A loop-shaped heat pipe having a liquid phase portion in which the interior is under negative pressure and a liquid working fluid is stored at the bottom, The first pipe section extends vertically, A second pipe section extending in the vertical direction, with its upper and lower ends communicating with the upper and lower ends of the first pipe section, An evaporator is provided in the lower part of the first pipe section for evaporating the working fluid in the liquid phase section, A condenser interposed above the liquid surface of the liquid phase portion of the second pipe section for condensing the vapor of the working fluid evaporated by the evaporator, A liquid collection unit that collects the working fluid condensed and liquefied in the condenser and drops it into the liquid phase portion of the second pipe section, A bypass pipe having one end opening between the condenser and the liquid collection section and the other end opening to the second pipe section between the liquid collection section and the liquid phase section, Having, The aforementioned heat pipe.

2. The heat pipe according to claim 1, further comprising an overflow pipe that allows the working fluid of the liquid collected in the liquid collection section to overflow at a predetermined liquid level in the liquid collection section and flow between the liquid collection section and the liquid phase section.

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