JPS6329192A - Thermal siphon type heat pipe - Google Patents

Abstract

PURPOSE:To alleviate restriction of dropping of liquid with a blowing gas and improve a limiting characteristic of thermal transportation by a method wherein a thermal transporting passage between an evaporation part and a condensation part is divided into two sections and a metering part having a minimum sectional area is arranged at a lower part of one flow passage. CONSTITUTION:Heat is applied to an evaporater part 3 from an external source to evaporate a working fluid or boil it, the generated gas may blow up both gas passage 11 and liquid passage 10. However, a metering part 12 is arranged at a lower part, a gas flow rate v2 at the upper end is lower than a flow rate v1 at the upper end of the gas passage 11 and even when liquid generated at a condensation part 1 may not be dropped, the liquid can be dropped from the upper end of the liquid passage 10. When liquid is held at the liquid passage 10, the gas flow rate blowing up within the liquid passage 10 is decreased, and the liquid can drop from the upper end of the liquid passage 10. With such a mechanism as above, finally only the gas is blown up in the gas passage 11 and only the liquid drops at the liquid passage 10 to make a stable condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermosiphon type heat pipe, and is particularly suitable for improving the critical characteristics of heat transport. As described in Japanese Patent Publication No. 51-60057, the flow path of the condensing section is divided into two into a liquid flow path and a gas flow path, and the flow resistance of the liquid flow path is increased at the lower end of the condensing section. . The purpose of this is to stabilize the movement of the heat medium in a certain direction.

No consideration was given to the limit on the amount of heat transport caused by suppression of liquid fall due to blown up gas (CCFL), which occurs when the amount of heat transport increases.

In addition, an invention aimed at alleviating the suppression of liquid falling due to blown up gas is disclosed in JP-A No. 53-34157, in which a funnel-shaped liquid flow with a communication port in the funnel wall is provided at the lower part of the condensing section. There are some with roads, but the structure is complicated.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into consideration liquid fall control (CCFL) due to blown up gas that occurs when the amount of heat transport increases, and either there is a limit to the amount of heat transport due to CCFL, or CCFL is relaxed. Therefore, there was a problem that the structure was complicated.

An object of the present invention is to improve the critical characteristics of heat transport by alleviating the suppression of liquid falling due to blown up gas.

[Means for solving problems]

The above purpose is to divide the flow path of the heat transport section between the evaporation section and the condensation section into a liquid flow path and a gas flow path, and to install a throttle with the smallest cross-sectional area in the flow path at the lower end of the liquid flow path. This is achieved by providing

[Effect]

The operation of the present invention will be explained by taking as an example the time of starting a heat pipe. The gas generated in the evaporation section initially blows up both the gas flow path and the liquid flow path, but the liquid flow path is equipped with a constriction at the bottom with the smallest cross-sectional area within the flow path. The gas flow velocity at the upper end is smaller than the flow velocity at the gas flow top end, and the liquid can fall from the liquid flow top end even if the liquid cannot fall due to the gas blown up at the gas flow top end. As a result, the flow resistance in the liquid flow path increases, and the gas flow rate that blows up the liquid flow path decreases, and from the end of the liquid flow path.

In addition, it allows liquid to fall. Due to this mechanism, the difference in gas flow velocity that blows up the gas flow path and the liquid flow path increases, and eventually a stable state is reached in which only gas blows up in the gas flow path and only liquid falls in the liquid flow path. Become. Conventional heat pipe operation during normal operation!
! ! (Japanese Patent Application Laid-open No. 51-60057),
In conventional devices, the liquid travels along the outer periphery of the tube wall and falls, so the area of the gas-liquid interface is large, and the liquid falling is easily suppressed by the blown up gas.However, in the present invention, the liquid is Since the liquid is caused to fall intensively from the constriction provided at the lower end of the liquid flow path, the area of the gas-liquid interface is reduced, and the suppression of the liquid falling due to the blown up gas is relaxed. In this way, the present invention has a simple structure in which the flow path inside the heat pipe is divided into two and a constriction with the smallest cross-sectional area in the flow path is provided at the bottom of one of the flow paths, thereby alleviating the suppression of liquid falling due to blown up gas. can do.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In this embodiment, a heat transport section 2 between an evaporation section 3 in which the working fluid evaporates due to heating from a high heat source and a condensation section 1 in which the working fluid condenses when it comes into contact with a heated object is connected to the liquid flow path 1o and the gas flow path 1o. The liquid flow path 10 is divided into two parts, and a throttle 12 whose cross-sectional area is the smallest in the flow path is provided at the bottom of the liquid flow path 10 . The operation of this embodiment will be explained using FIGS. 2 and 3, taking as an example the case where the heat pipe is activated. In FIG. 3, the flow rate of the liquid that can fall is limited by the blown up gas. This shows the so-called CCFL characteristic, which indicates that liquid cannot fall above a certain gas flow rate. As shown in FIG. 2(a), when heat is applied to the evaporator 3 from the outside to evaporate or boil the working fluid, the generated gas blows up both the gas flow path 11 and the liquid flow path 10. However, since the throttle 12 is provided at the lower part of the liquid flow path 1o, the gas flow velocity vz at the upper end of the liquid flow path 1o is equal to that of the gas flow path 11.
Even if the liquid generated by condensation in the condensation section 1 cannot fall from the upper end of the gas flow path 11, as shown in FIG.
Liquid can fall from the top of 0. As shown in FIG. 2(b), when the liquid is retained in the liquid flow path 10, the flow resistance within the liquid flow path 10 increases, the gas flow rate that blows up the liquid flow path decreases, and the liquid flow path 10 More liquid will be able to fall from the top. Due to such a mechanism, the difference in gas flow velocity that blows up the gas flow path 11 and the liquid flow path 10 increases, and eventually only the gas blows up in the gas flow path 11, as shown in FIG. 2(c). In the liquid flow path 1o, the working fluid becomes stable when only the liquid falls.The working fluid used in this embodiment may be any condensable gas heat medium, and examples thereof include water, freon, ammonia, and the like.

In addition, the condensing section 1. Heat transport section 2. As a material for the evaporation part 3, a metal with good thermal conductivity, such as stainless steel, may be used.As an example of a design based on this embodiment, water at atmospheric pressure is used as the working fluid, and the diameter of the heat transport part 2 is 0.1
m, the length is 3 m, and the cross-sectional area ratio of the gas flow path 11 and the liquid flow path 10 is 9:1, the maximum flow rate of water that can fall through the liquid flow path 10 is between the gas flow path 11 side and the liquid flow path. Flow'Jl!
Determined from the pressure balance with the 110 side, maximum 0°9
7 kg/s, and the heat transport amount is 2.2 MW. On the other hand, in conventional devices, the liquid travels along the outer periphery of the tube wall and falls, so the area of the gas-liquid interface is large, and the blown up gas tends to suppress the water from falling. When the same shape and the same working fluid are used, the maximum flow rate of water that can fall is determined by the characteristics of suppressing water fall due to blown up gas, and the maximum flow rate is 0.
16 kg/s = heat transport amount is 0.36 MW, which is approximately - compared to the first embodiment.The orifice 12 in the first embodiment may be an orifice or a nozzle, and the flow path is interrupted. It is desirable that the area be smaller than 90% of the cross-sectional area of the liquid flow path 10. In addition, when an orifice is used as the restrictor 12, it may have a tapered shape (a) that widens toward the end against reverse flow, as shown in FIG. 4, to reduce flow resistance against forward flow and increase flow resistance against reverse flow. , it is desirable to have a bellmouth shape (b). As described above, according to this embodiment, the flow path inside the heat pipe is divided into two, and the cross-sectional area of the lower part of one flow path is made the smallest in the flow path. With this simple structure, the suppression of liquid falling due to blown up gas can be alleviated, and the critical characteristics of heat transport can be improved.

Another embodiment of the present invention will be described with reference to FIG.

In FIG. 5(a), a pressure gauge 20 is added on the upstream side of the throttle 12, and a pressure gauge 21 is added on the downstream side. In the heat pipe of this embodiment, since the liquid is held inside the liquid flow path 10, a pressure balance as shown in FIG. 5(b) is established. If the pressure difference before and after the throttle 12 is ΔPa, then ΔPa
is expressed by the following formula.

Here, Ko: Pressure loss coefficient (-) ωl at the throttle:
Liquid flow rate (kg/s) ρl: Liquid density (kg/bo) Ao: Cross-sectional area of the aperture (po) (1) Expression is ω! In this embodiment, in the arithmetic unit 22, the pressure P2 measured by the pressure gauge 21 is subtracted from the pressure P1 measured by the pressure gauge 20, and ΔP is obtained.
o is determined, and ρ1 is determined from the pressure P2 based on the relational expression between pressure and the density of the liquid. The values of Ao and Ko are actually measured values and stored in the storage device 23 in advance. The arithmetic unit 22 uses the above values of ΔPa, px, Ao, and Ko to calculate equation (2) to obtain ω1. Furthermore, the pressure P
Display device for searching at x! ! Displayed on 24. Arithmetic device! !
! 22 and the storage device 23 may be configured by digital circuits, or may use commercially available microcomputers.In this way, in this embodiment, by relaxing the suppression of liquid falling due to blown up gas, heat transport is improved. In addition to improving the critical characteristics of , it also has the effect of determining the amount of heat transport from pressure measurements and monitoring this value.

Still other embodiments of the present invention will be described with reference to FIGS. 6 to 8. In this example, the heat pipe of the present invention is applied to a decay heat removal system of a natural circulation nuclear reactor. FIG. 6 shows a vertical cross section of the natural circulation reactor and the water storage tank 111. A large number of heat pipes 31 are inserted into the water storage tank 111, and the heat pipes 31 are connected to the connecting pipe 3.
2 is connected to a heat pipe 3o outside the containment vessel 120. In such a nuclear reactor, e.g.

When the cooling water in the reactor vessel 101 flows out due to a rupture in the instrumentation pipe or the like, the water level in the reactor vessel 101 decreases, and the control rods 105 are inserted into the reactor core 102.

Although the core 102 scrams, the decay of the fission products continues to generate heat in the core 102 that needs to be removed. The operation of the water storage tank 111 at the time of such a coolant loss accident will be explained with reference to FIG. FIG. 7(a) shows the state during normal operation, and since the cooling water in the riser pipe 112 and the water injection pipe 113 are both kept at a low temperature, the water storage tank 111 and the reactor vessel 101 There is no circulation of cooling water between the reactor vessel 101 and a loss of coolant accident occurs, as shown in Fig.
When the water level in the reactor vessel 101 becomes lower than the lower end of the riser pipe 112, steam in the reactor vessel 101 flows into the water storage tank 111 through the riser pipe 112, heating the cooling water in the water storage tank 111, and Pressure inside tank 111 and reactor vessel 1
The pressure inside 01 is equalized. Since the water level in the water storage tank 111 is maintained higher than the water level in the reactor vessel 101, when the pressure in the water storage tank 111 and the pressure in the reactor vessel 101 are equalized, the water level in the water storage tank 111 The cooling water inside the reactor vessel 101 falls by gravity through the water injection pipe 113.
automatically supplied to the inside.

Moreover, when the cooling water in the water storage tank 111 is heated by the steam flowing in through the riser pipe 112, a temperature difference occurs between the inside and outside of the water injection pipe 113, and the radiator 114 provided in the water injection pipe 113 is heated. Operates automatically. By supplying cooling water into the reactor vessel 101, the water level inside the reactor vessel 101 recovers, as shown in FIG. 7(c), and the water level rises to the riser pipe 112.
When the water rises above the lower end, steam no longer flows into the water storage tank 111 through the riser pipe 112, so the water injection pipe 11
3 into the reactor vessel 101 is also automatically stopped, but at this time, the cooling water in the water injection pipe 113 is at a high temperature. For this reason, the cooling water in the water injection pipe 113 is cooled by the radiator 114, and the lower temperature cooling water increases in density and descends, whereas the cooling water in the rising pipe 112 is not provided with a radiator. Therefore, due to the high temperature and low density, the reactor vessel 101, riser pipe 112. Water storage tank 111. A natural environment surrounding the water injection pipe 113 and the reactor vessel 101 is established. FIG. 8 shows a vertical cross-sectional view of the heat pipe 30, heat pipe 31, and connecting pipe 32 in FIG.
A large number of heat pipes 31 having the same configuration as shown in the figure are attached, and these heat pipes 31 are connected to a heat pipe 30 outside the containment vessel 120 shown in FIG. 6 by a connecting pipe 32. .

The inside of the connecting pipe 32 is divided into two by a partition plate 34. The internal structure of the heat pipe 30 is the same as that shown in FIG. 1, and a radiator 33 is attached to the condensing section to promote heat release. The heat radiator 33 is constituted by a fin, and its material is a metal 1 with good thermal conductivity, such as stainless steel. A loss of coolant accident occurs, and as explained in Figure 7, reactor vessel 101
° Rising pipe 1121 Bodhisattva tank 111. When the natural circulation that circulates through the water injection pipe 113 and the reactor vessel 101 is established, the working fluid inside the heat pipe 31, for example, water,
The generated steam is evaporated by the heat from the water storage tank 111 and is led to the heat pipe 30 through the connecting pipe 32, where the heat is absorbed and condensed in the condensing section to which the radiator 33 is attached. In such a state, based on the mechanism shown in FIG. 2, only water falls in the flow path provided with the throttle, and only steam blows up in the flow path without the restriction. As described above, in this embodiment, since the gas flow path and the liquid flow path are separated, the suppression of liquid falling due to the blown up gas is alleviated, and the limit characteristics of heat transport are improved. Also,
This is because a large number of heat pipes 31 are inserted inside the water storage tank 111.

The heat transfer area in the heating section becomes larger, and the overall amount of heat transport can be increased. In addition, the heat pipe 30 of this embodiment includes pressure gauges 20 and 21 and a calculation device, similar to the embodiment shown in FIG. 22, storage device 23 and display device 1!
24 is attached to the heat pipe 30, and the liquid flow rate and heat transport amount can be determined and displayed from the pressure difference before and after the throttle attached to the lower part of the liquid flow path of the heat pipe 30. Being able to monitor the internal state in this way is a desirable function in a safety system such as the decay heat removal system of an S reactor.

In this way, this embodiment has the effect of improving the limit characteristics of heat transport by relaxing the suppression of liquid falling due to blown up gas, the effect of determining the amount of heat transport from pressure measurement and monitoring this value, and the effect of being able to monitor this value by determining the amount of heat transport from pressure measurement. This has the effect of increasing the heat transfer area and increasing the overall amount of heat transport.

Still another embodiment of the present invention will be described with reference to FIG.

In FIG. 9, several ultrasonic sensors 40 each consisting of an ultrasonic oscillator and an ultrasonic receiver are installed in the height direction outside the liquid flow path 10. FIG. 10 shows the relationship between the water level and the reflected intensity of ultrasonic waves. When the water level is lower than the sensor position, the ultrasonic waves are totally reflected by the metal surface, so the reflected intensity is large. When the water level reaches the sensor position, the ultrasonic waves will be transmitted from the metal surface into the water, and the reflected intensity will drop rapidly. After that, the reflection intensity gradually decreases as the water level rises.
The water level is measured from the reflection intensity measured at 0 using the relationship shown in FIG.

Next, a method for determining the liquid flow rate from the water level will be described.

The pressure loss ΔP□ on the side of the gas flow path 11 is a function of the gas flow rate ωg, and is expressed as ΔPt=fx(0g). On the other hand, the pressure loss ΔP on the liquid flow path 10 side is the liquid flow rate. □ and water level Li
It is the sum of the functions of ΔP(=fz(ω1)+fδ(T,
,! It is expressed as >. In steady state, ωg=ωf,
Since the pressure balance is established between the gas flow path 11 side and the liquid flow path lO#I, fx (ω1) = fz (ωz) + fδ
(Ll>).

If fs(ωt)−fz(ω,) is newly expressed as h(ω□), ω is expressed as h−x(fs(i)). However, h−x(χ) is an inverse rM number. The arithmetic unit 42 uses this relationship to determine the liquid flow rate ωl from the water level, and further multiplies it by the latent heat of vaporization during steady state to determine the amount of heat transport, which is displayed on the display device 43. In this way, in this embodiment, in addition to improving the limit characteristics of heat transport by relaxing the suppression of liquid falling due to blown up gas, the heat transport amount is determined by measuring the water level from the outside of the heat pipe, and this value is calculated. It is effective in monitoring the

〔Effect of the invention〕

- According to the present invention, it is possible to separate the gas flow path and the liquid flow path with a simple structure, so it is possible to alleviate the suppression of liquid falling due to blown up gas and improve the critical characteristics of heat transport. can.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of one embodiment of the present invention, Fig. 2 is an explanatory diagram showing the operation progress of the embodiment of Fig. 1, Fig. 3 is a diagram showing falling liquid and the blow-up effect, Fig. 4 is a partial detailed longitudinal cross-sectional view of the embodiment of FIG. 1, FIG. 5 is a longitudinal cross-sectional view of another embodiment of the present invention,
FIG. 6 is a longitudinal sectional view of still another embodiment of the present invention, FIG. 7 is an explanatory view showing the operation progress of the embodiment of FIG. 6, and FIG. 8 is a partial longitudinal sectional view of the embodiment of FIG. 6. , FIG. 9 is a longitudinal sectional view of another embodiment of the present invention, and FIG. 10 is a graph showing the relationship between water level and reflection intensity. 1... Condensation section, 2... Heat transport section, 3... Evaporation section,
10...Liquid channel, 11...Gas channel, 12 River aperture, 20゜21...Pressure gauge, 30.31...Heat pipe, 32゛° connection 9-40゛゛゛゛ultrasonic + bar
, fT? ＞Representative Patent Attorney Katsuo Ogawa
Knee, ゛□You 3 Figure Older Figure 1〇-Table Salary Flow 2 1z-11 Squeeze 21 (C) Fan 5 Figure (α) (d) Pressure also 8 Figure (C) B Figure V (α) (Ice) (C) Water level

Claims (1)

[Claims] 1. In a thermosiphon heat pipe consisting of a sealed tube, an evaporating section that contacts a high heat source at one end, and a condensing section that contacts a heated object at the other end, the evaporating section and A thermosiphon type heat pipe characterized in that the flow path of the heat transport section between the condensation section and the condensation section is divided into two, and a constriction is provided at the bottom of one of the flow paths to minimize the cross-sectional area within the flow path. 2. The thermosiphon type heat pipe according to claim 1, wherein a plurality of the thermosiphon type heat pipes are connected by a connecting pipe. 3. In claim 1, there is provided: means for measuring the pressure on the upstream and downstream sides of the throttle, means for determining the liquid flow rate and heat transfer amount from the pressure, and displaying the liquid flow rate and heat transfer amount. A thermosiphon type heat pipe characterized by being provided with a means. 4. In claim 1, means for measuring the water level in the flow path provided with the throttle using ultrasonic waves, means for determining the liquid flow rate and the heat transport amount from the water level, and the liquid flow rate and the heat transfer amount. A thermosiphon type heat pipe characterized by being provided with a means for displaying the amount of transportation.