JPH03274364A - Boiling type cooling device - Google Patents

Abstract

PURPOSE:To prevent a reduction in performance caused by corrosion and to get superior cooling performance without using fluorocarbon by a method wherein an evaporator storing cooling liquid of aqueous solution of ethylene glycol and a copper condenser connected to the evaporator are provided. CONSTITUTION:Cooling liquid 25 of aqueous solution of ethylene glycol is stored in an evaporator 21. In order to resist in corrosion against this aqueous solution, evaporator 21, condenser 22, steam pipe 23 and liquid return pipe 24 are made of copper. A thyristor element 3 acting as a cooled member is pressure welded to the evaporator 21. With such an arrangement, the thyristor element 3 is cooled by the cooling liquid 25, steam 27 generated under boiling state is condensed by the condenser 24 and again returns back into the evaporator 21. At this time, since aqueous solution of ethylene glycol is used as the cooling liquid 25 in a boiling type cooling device, there is no problem of pollution of environment caused by fluorocarbon gas or the like. In addition, the device is made of copper, corrosion caused by aqueous solution of ethylene glycol can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a boiling cooling device for cooling thyristor elements of chopper devices installed in subway cars, power transistors used in electronic equipment, etc. It is related to. [Prior Art] FIG. 54 is a configuration diagram showing a conventional immersion type evaporative cooling type thyristor device disclosed in, for example, Mitsubishi Electric Technical Report Vol. 48, No. 2. In the figure, a fluorocarbon liquid (2) such as R113 is placed in an evaporator (1), and a thyristor element (3) is immersed in this fluorocarbon liquid (2) to be cooled. A fin (4) is physically connected to the thyristor element (3). Further, the terminal (5) of the thyristor element (3) is drawn out of the evaporator (1). A condenser (8) is connected to the upper part of the evaporator (1) via a steam pipe (6) and a liquid return pipe (7).
> are connected. Next, the operation will be explained. When the thyristor element (3) is activated, power losses occur within it, resulting in the generation of a high amount of heat of several hundred watts. on the other hand,
The cooling surface of this thyristor element (3) has a diameter of several 1011
Since the area is small, the heat flux of the cooling surface is io
'The value is as high as W/1. The heat generated in the thyristor element (3) in this way is radiated to the fluorocarbon liquid (2) from the fins (4) that are pressed against the cooling surface of the thyristor element (3). As a result, the Freon liquid (2) boils and moves to the evaporator (1).
1. The generated fluorocarbon vapor (2a) enters the condenser (8) through the steam pipe (6), is condensed in the condenser (8>), and becomes the fluorocarbon liquid (2a) again. 2〉
This condensed Freon liquid (2) is passed through the liquid return pipe (
7) and returns to the evaporator <1). By repeating such operations, the thyristor element (3) continues to be cooled. Next, Fig. 55 shows, for example, the heat dissipation design and simulation of electronic equipment J (published by Applied Technology Publishing, 1989), No. 148.
FIG. 2 is a configuration diagram showing a conventional individual cooling fin type (non-immersion type) boiling cooling system SIRISK device shown in FIG. In the figure, the thyristor element (3) is exposed to the atmosphere. Each thyrisk element (3) has cooling fins (9
) is attached. Each cooling fin (9>) is connected to a common liquid reservoir (11) via a heat transport pipe (lO).These cooling fins (9), heat transport pipe (10> and common liquid reservoir (11) The common liquid reservoir (11) contains the steam pipe (6>) and the liquid return pipe (2).
7> to a condenser (8). Next, the operation will be explained. The heat generated by the thyristor element (3) is transferred to the fluorocarbon liquid (2) via the cooling fins (9).
). As a result, the fluorocarbon liquid (2) evaporates and fluorocarbon vapor (2a) is generated.1 The generated fluorocarbon vapor (2a) flows through the heat transport pipe (10), the common liquid reservoir (11), and the steam pipe (6). It enters the condenser (8), and is condensed in this condenser (8> to become a fluorocarbon liquid (2) again. This condensed fluorocarbon liquid (2) flows through the liquid return pipe (7) by gravity.
) and returns to the common liquid reservoir (11). By repeating such operations, the thyristor element (3) continues to be cooled. By the way, FIG. 56 is a relationship diagram between overblackness and heat flux showing a boiling curve of a general refrigerant. In the figure, point A to B
The points are areas of natural convection, and points B to C to D are areas of nucleate boiling. Point D is called the burnout point, and the heat flux at point D is called the burnout heat flux. Point D ~ E
The point is the region of transition boiling, and the points E to F to G are the region of film boiling. Normally, when the heat flux changes from low to high, it exhibits a characteristic that goes from point A to point B and then to point H'. Then, when the heat flux is further increased, it moves from point H' to point H, and when the heat flux is further increased, it exhibits a characteristic that it reaches point D from point H via point 0. Conversely, if the heat flux is lowered, it will reach point H from point D via point 0, but even if the heat flux is further reduced, it will not move to point H' and will continue from point H via point B. Indicates the characteristic of returning to point A, -
In boat fishing, this phenomenon is said to have hysteresis. That is, in the conventional boiling cooling method as described above, the heat flux between point B and point D shown in FIG. (
1) The heat transfer area was determined. Further, even if the heat transfer area of the evaporator (1) was determined by understanding these characteristics, when the refrigerant was changed, it was necessary to understand the boiling characteristics of the new refrigerant. [Problems to be Solved by the Invention] The conventional boiling cooling type thyristor device configured as described above has the following problems. ■ Each uses a fluorocarbon liquid (2) as a coolant, but since fluorocarbons destroy the ozone layer when released into the atmosphere, it is necessary to use a refrigerant other than fluorocarbons from the standpoint of environmental conservation. In addition, when using refrigerants other than fluorocarbons,
Because its physical properties are different from those of fluorocarbons, conventional devices will not be able to provide sufficient cooling performance in various respects. ■ Among conventional devices, the individual cooling fin type has a common liquid reservoir (11) placed above the cooling fins (9), which increases the overall height, making it difficult to install this thyristor device. Equipment (e.g. railway vehicles, etc.)
This requires a large installation space, which hinders the ability to make the device more compact. In particular, in the case of linear motor cars, there is a strong demand for the vehicle to be compact, that is, to have a low floor, so it is even more necessary to reduce the height dimension of the thyristor device. (2) Although objects to be cooled such as power transistors are subjected to larger currents, conventional devices do not have sufficient cooling characteristics, especially when the heat load is small. ■ When designing the evaporator (1) or cooling fins (9), the heat flux at the point where boiling starts is not taken into consideration, so even if the heat flux is the same, near point H in Figure 56, Evaporator(
1) The degree of superheat, which is the difference between the wall surface temperature and the refrigerant temperature, fluctuates, making the cooling characteristics unstable. The invention according to claim (1) has been made with the aim of solving the above-mentioned problems, and is characterized in that it provides a boiling cooling device with excellent cooling performance without using fluorocarbons. The inventions according to claims (2) and (3) have been made with the aim of solving the above-mentioned problems, respectively, and provide a boiling cooling device that can reduce the overall height dimension. The invention according to claim (4), characterized in that it obtains The invention according to claim (5) is characterized in that it provides a boiling cooling device that can improve the cooling characteristics when the heat load is small and thereby improve the cooling characteristics as a whole. The invention according to claim <6> is made with the aim of solving the above problems, and is characterized by obtaining a boiling cooling device that can improve cooling characteristics over a wide range of heat loads. was developed with the aim of solving the above-mentioned problems, and can effectively promote heat transfer.This allows cooling liquids made of water or ethylene glycol aqueous solution to be used without using CFCs. The invention according to claim (7), which is characterized in that it provides a boiling cooling device that can provide superior cooling performance, has been made with the aim of solving the above-mentioned problems, A claim characterized in that it is possible to obtain a boiling cooling device that can prevent a decline in cooling performance due to leakage, thereby providing excellent cooling performance with a cooling liquid made of water or an aqueous ethylene glycol solution without using fluorocarbons. The inventions according to (8), (9) and (10) were made with the aim of solving the above-mentioned problems, respectively, by preventing fluctuations in the degree of superheating of the evaporator and improving cooling performance. It is an object of the present invention to obtain a boiling cooling device that can be stabilized. [Means for solving the problem] The boiling cooling device of the invention according to claim (1) uses a cooling liquid consisting of an ethylene glycol aqueous solution, and The boiling cooling device of the invention according to claim (2) is one in which an evaporator is connected to the side of a common liquid reservoir via a duct oriented in a roughly horizontal direction. In the SM cooling device of the invention according to claim (3), the evaporator is connected to the side of the common liquid reservoir via a duct oriented in a substantially horizontal direction, and the evaporator is connected to the inside of the heat absorption surface of the evaporator. A plurality of internal flow passages extending in the vertical direction are provided on the inside. The boiling cooling device of the invention according to claim (4) is one in which a liquid cooling cooler for cooling an inflowing cooling liquid is connected to an evaporator. The evaporative cooling device of the invention according to claim (5) includes a first refrigerant flow path and a second refrigerant flow path having a smaller cross-sectional area than the first refrigerant flow path in parallel to each other in the evaporator. It was established. The boiling cooling device of the invention according to claim (6) uses water or an aqueous ethylene glycol solution as the cooling liquid, and has particles having a particle size of 300 μm or more and 2000 μm on the heat transfer surface in the evaporator.
It is made by fixing a large number of heat transfer promoting particles with a size of less than m. The boiling cooling device of the invention according to claim (7) uses water or an aqueous ethylene glycol solution as the cooling liquid, and the monitoring means for monitoring the pressure in the space above the liquid level of the cooling liquid is provided facing the space. In addition, an exhaust means is connected to the space to reduce the pressure inside the space when the pressure rises abnormally. In the evaporative cooling device of the invention according to claims (8), (9), and (10), the heat transfer area of each evaporator is set to a heat flux value equal to or higher than the boiling start point of the refrigerant. [Function] In the invention according to claim (1), the object to be cooled is cooled by an aqueous solution consisting of an ethylene glycol aqueous solution, and the condenser is made of copper, thereby preventing corrosion of the condenser. In the invention according to claim (3), the overall height is characterized by arranging the evaporator on the side of the common liquid reservoir.In the invention according to claim (3), the evaporator is arranged on the side of the common liquid reservoir. This reduces the overall height and provides multiple internal channels within the evaporator to facilitate air bubble movement and improve the evaporative cooling system. In the invention according to claim (4), the cooling liquid that convects due to heat absorption is cooled by flowing into the liquid cooling cooler. In the invention according to claim (5), by providing the evaporator with the second refrigerant flow path having a smaller cross section than the first refrigerant flow path, cooling efficiency is increased when the heat load is small. In the invention according to claim (6), heat transfer promoting particles of an optimum particle size are fixed to the heat transfer surface in the evaporator to effectively promote heat transfer, and pure water or ethylene glycol is used as the cooling liquid. Improves cooling performance when using aqueous solutions. In the invention according to claim (7), water or an aqueous ethylene glycol solution is used as the cooling liquid by monitoring the pressure in the space by the monitoring means and reducing the pressure in the space by the exhaust means when the pressure increases abnormally. In the inventions according to claims (8), (9), and (10), the heat transfer area of the evaporator is set to a heat flux value equal to or higher than the boiling start point of the refrigerant. This prevents fluctuations in the degree of superheating. [Example] Hereinafter, an example of the invention according to claim (1) (hereinafter referred to as the first invention) will be described with reference to the drawings. It is a configuration diagram showing an individual cooling fin type boiling cooling device. In the figure, the evaporator (21) has a steam pipe (22>) which is a vapor flow path and a liquid return pipe (23) which is a liquid return flow path. A condenser (24) is connected to the condenser (24) through a plurality of fin tubes (24).
m), and first and second headers (24b) and (24c) provided at both ends of the fin tube (24a). The evaporator (21) contains a cooling liquid (25) made of an aqueous ethylene glycol solution.The evaporator (21) is resistant to corrosion against this aqueous ethylene glycol solution.
, condenser (22), steam pipe (23) and liquid return pipe (24)
) are made of copper. Further, a thyristor element <3> as a cooled body is pressed into contact with the evaporator (21). In the boiling cooling device configured as described above, the thyristor element (3
) is cooled. Also, steam generated by boiling (27)
is condensed in the condenser (24) and then returned to the evaporator (21)
Go back inside. At this time, since the above-mentioned boiling cooling device uses an ethylene glycol aqueous solution as the cooling liquid (25), there is no problem of environmental damage such as chlorofluorocarbon gas.Also, since the device is made of copper, ethylene glycol aqueous solution is used as the cooling liquid (25). Corrosion is prevented1 For example, ethylene glycol3
In the case of an 8@t% aqueous solution mixed with an anticorrosion agent, the corrosion rate is 0.041 mm/year for mild steel and 0.059 mm/year for zinc.
uz/year, copper is 0.0O17iv/year. Therefore, corrosion of the device is prevented, and generation of non-condensable gas (eg, hydrogen) accompanying corrosion is also prevented. Here, FIG. 2 is a diagram showing the relationship between the degree of superheat of the heat transfer surface and the heat flux, showing the respective boiling curves of Freon R113, water, and a 35-t% aqueous solution of ethylene glycol. Regarding the boiling cooling performance of each of these refrigerants, water is the best, followed by 35 wt% ethylene glycol aqueous solution and Freon R11.
The order is 3. In Fig. 2, water and ethylene glycol 35 wt% aqueous solution are actually measured values, and Freon R113 is L ab which is an estimation formula for nucleate boiling heat transfer.
It was calculated using the auntzov formula. The formula of this L abountzov is shown below. IQ/(L-γv) l-1, / ν, < 10-2
In the case α・12/λ, ==0.0625f: (Q/(L
・γ)・12/ν,]05×p,,l/3 +Q/(L・γ,))・12/ν□>10-2 α
・12/λ, = 0.125[:+Q/(L・γ9
〉)・12/ν,]G, @S×P, , l/3 12-<c,, (T, +273)/L l(γ1/γ
V)×(σ/(J・γ,・L)1 Where, Q: Heat flux (keal/s+”hr) L: Latent heat of vaporization (keal/Ag) γ0. Specific weight of liquid (kg/x”) γ,: specific weight of steam (kg/l>): kinematic viscosity coefficient of liquid (m'/br) α: heat transfer coefficient (Acal/ +w"hr"C) λ1: heat transfer coefficient of liquid (^cat/ 1hr”c) C0: Specific heat of liquid (Acal/k'9°C) σ: Surface tension (kg/wealth) J = 426.8 (keal keal)T,;
Wall i ("C) P,: Prandtl number of the liquid (->). As is clear from Fig. 2, when the saturated liquid temperature is 70°C,
The boiling cooling property of the ethylene glycol 38@t% aqueous solution is inferior to that of water, but is approximately equal to or better than that of Freon R113. On the other hand, although water has excellent boiling cooling properties, it turns into ice when the temperature drops to 0°C, so in order to install it in vehicles, etc., it is necessary to design it with anti-freezing measures and startup characteristics at low temperatures. On the other hand, as shown in Fig. 3, the freezing temperature of an ethylene glycol aqueous solution can be lowered depending on its concentration.For example, as shown in Fig. 2, A 35wt% aqueous solution has a freezing temperature of -20°C, and can be sufficiently applied to the operating temperature range (usually -20°C to 80°C) of thyristor elements (3). However, an ethylene glycol aqueous solution As shown in Fig. 4, the saturation pressure of the thyristor element (3) in the operating temperature range is lower than atmospheric pressure, so non-condensable gas (e.g. air) enters from leaks etc., causing cooling. It is necessary to manufacture the device so that its performance does not deteriorate. In the above embodiment, the entire device is made of copper, but the parts other than the condenser (24) may be made of other materials. However, from the viewpoint of corrosion resistance as mentioned above, it is still preferable to use copper, especially for the parts where the vapor (27) of the ethylene glycol aqueous solution is present, such as the steam pipe (22>). Cooling liquid that tends to be a glycol aqueous solution (25
) may be used by adding a corrosion inhibitor or the like to more reliably prevent corrosion. Furthermore, in the above embodiment, a steam pipe (22) is used as a steam flow path.
Although the liquid return pipe (24) is shown as the liquid return flow path, it goes without saying that the liquid return pipe is not limited to a tubular shape. Furthermore, although the above embodiment shows an individual cooling fin type boiling cooling device for a thyristor device, the first invention can be applied to any other boiling cooling device. Hereinafter, an embodiment of the invention according to claim (2) (hereinafter abbreviated as the second invention) will be described with reference to the drawings. FIG. 5 is a side view, partially in section, of an individual cooling fin type boiling cooling device for a thyristor device according to the first embodiment of the second invention, and FIG. 6 is a front view of FIG. 5. In the figure, cooling fins (31), which are evaporators, are individually attached to thyristor elements (3), which are objects to be cooled. A duct <32> oriented in the horizontal direction is attached to the side of each cooling fin (31).
The cooling fins (31) are connected to the sides of the common liquid reservoir (33) via this duct (32). Common liquid reservoir (33
) is connected to the upper part of the condenser (24). Further, pure water or an ethylene glycol aqueous solution is used as the cooling liquid (25). Next, the operation will be explained. The heat generated in the thyristor element (3) exposed to the atmosphere is transferred to the cooling fin (31
). This heat causes the cooling liquid (25> in the cooling fins (31) to boil, and bubbles (26>) are generated from the endothermic surface (31a) and rise.As the bubbles (26) rise, the cooling liquid (25>) in the cooling fins Coolant (25) in (31)
convects as shown by the arrow in the figure. The air bubbles (26> that have risen inside the cooling fins (31) move to the common liquid reservoir (33>) through the duct (32>) and enter the first header (24b>) from the liquid surface. The header (24b) is filled with steam (27). This steam (27) is air-cooled in the condenser (24), condenses,
This cooling liquid (25) liquefies and becomes a cooling liquid (25) again.
) returns to the common liquid reservoir (33) by gravity and further returns to the cooling fins (31) to cool the thyristor element (3). , and because the cooling fins (31) are arranged on the sides of the common liquid reservoir (33), the overall height is smaller than before.Here, in the above embodiment, the pure cooling liquid (25) is Since water or ethylene glycol aqueous solution is used, the cooling method for the thyristor element (3) is not only boiling, but also convection, or convection and boiling. In the device of the above embodiment, the duct (32> is oriented almost horizontally, and the cooling fins (31) are arranged on the side of the common liquid reservoir (33), so that the air bubbles (26>) are As well as moving smoothly, the cooling liquid (25)
The convection is promoted, and the cooling characteristics are improved compared to the conventional device shown in FIG. By the way, when using pure water or ethylene glycol aqueous solution as the coolant (25) in this way, the operating temperature is between -2 and 2.
Since the temperature is about 0 to 60℃, the pressure of steam (27) is 15
The low pressure state of 0yiHg or less is the same as in the embodiment of the first invention. Next, FIG. 7 is a sectional view of a boiling cooling device according to a second embodiment of the second invention. In the figure, each cooling fin (31) and the common liquid reservoir (33
An upper duct (34) and a lower duct (35), which are ducts oriented substantially horizontally, are interposed between the upper and lower ducts. These upper ducts (34) and lower ducts (35〉) are arranged parallel to each other and spaced apart above and below, similar to other ellipsoids or those in Fig. 5. Such boiling cooling In the device, since air bubbles (26) pass through the upper duct (34), the upper duct (34) directs the cooling liquid (
25) flows, and in the lower duct (34>, a common liquid reservoir <33
The cooling liquid <25> flows from the cooling liquid <25> toward the cooling fins (31). For this reason, a cooling liquid (25) as shown by the arrow in the figure is used.
The convection is further promoted, and the cooling properties are further enhanced. Next, FIG. 8 is a sectional view of a boiling cooling device according to a third embodiment of the second invention. In the figure, the cooling fins (31) are extended upward compared to those in FIG. 7, and the liquid level of the cooling liquid (25) is located above the heat absorption surface within the cooling fins (31). The liquid level of the cooling fins (31) and the liquid level of the common liquid reservoir (33) or the first header (24b) are connected by a steam duct (36) that is a duct. That is, the cooling fins (31) and the common liquid reservoir 33) are connected by three ducts. In such a boiling cooling device, by providing a dedicated steam duct (36) for steam (27), air bubbles (26)
While utilizing the convection of the cooling liquid (25) as it moves,
Steam (27) can be moved to the condenser tank 24) without being hindered by the cooling liquid (25) returning from the condenser (24). Therefore, the cooling characteristics are further improved. Next, FIG. 9 is a sectional view of a boiling cooling device according to a fourth embodiment of the second invention. In the figure, the condenser (24) is tilted in the opposite direction to that in FIGS. 24c) is lower.A liquid return pipe (37) is provided between the lower part of this second header (24c) and the common liquid reservoir (33).Also, the first header The lower end of (24b) also serves as a common liquid reservoir.According to this embodiment, since the steam flow path can be made large, the pressure loss of the steam (27) is small, and the steam (27) can be easily made uniform. Also, the condensed cooling liquid (25) is transferred to the liquid return pipe (
37> and returns to the common liquid reservoir (33), the condensed cooling liquid (25) and steam (27) do not come into contact with each other immediately, resulting in good cooling efficiency. In addition, in each of the above examples, pure water or ethylene glycol aqueous solution was used as the cooling liquid (25), but
It is also possible to use other aqueous solutions or fluorocarbon solutions. Moreover, although the above-mentioned embodiments use one to three ducts, four or more ducts may be used. Further, the cross-sectional shape of the duct may be circular, rectangular, or polygonal, and for example, a bellows may be used in part or the whole as shown in FIG. 21, which will be described later. Furthermore, in the above embodiment, the thyristor element (3) is shown as the object to be cooled, but the object is not limited to this. Hereinafter, an embodiment of the invention according to claim (3) (hereinafter abbreviated as the third invention) will be described with reference to the drawings. FIG. 10 is a cross-sectional view of essential parts of the boiling cooling device according to the first embodiment of the third invention, FIG. 11 is a cross-sectional view taken along line A-A in FIG. 10, and FIG. 12 is B in FIG. - Arrow section along line B'
@Figure. In the figure, inside the endothermic surface (31a) of the cooling fin (31) that is the evaporator, there is a block-shaped niremen (41
) is provided. The device in this example is made of copper;
For this reason, the element (41) is also made of copper.The element (41) is provided with a large number of circular ducts (42) each having a circular cross section and serving as an internal flow path extending in the vertical direction. Note that the other configurations are the same as those shown in FIG. 5. In the boiling cooling device as described above, cooling fins (3
1) is placed on the side of the common liquid reservoir (33),
Like each embodiment of the second invention, the overall height is low. In addition, since a circular duct (42) extending vertically is formed within the cooling fin (31), air bubbles (
26) is guided by this and rises smoothly, thereby promoting boiling cooling and convection, improving the cooling characteristics of the cooling fins (31), especially when the heat load is small. Here, Figure 13 is a diagram showing the relationship between the degree of superheating and the heat flux, showing the experimental results of the boiling cooling characteristics of a vertical circular tube when pure water is used as the coolant. was assumed to be a uniform heat flux condition. Also, the vertical circular pipe has an inner diameter of φ3
Items 1 to 9 and lengths of 40 to 80 mm were used. Furthermore, for comparison, a horizontal disk (diameter φLol
The boiling cooling characteristics of 1) are shown by broken lines. As shown in the experimental results, the boiling cooling characteristics of the vertical circular tube are excellent even in the region where the heat flux is small below the boiling starting point of the horizontal disk. Furthermore, Figure 14 is a diagram showing the relationship between the degree of superheating and the heat flux, showing the experimental results of the boiling cooling characteristics of a vertical circular tube when an ethylene glycol aqueous solution (20wt%, 35wt%) is used as the cooling liquid. The temperature was 60° C., and the heat transfer surface had uniform heat flux conditions. In addition, the vertical circular pipe has an inner diameter of φ6~1
2+11, length 8011 was used. Furthermore, for comparison, the boiling cooling characteristic of a horizontal disk (diameter φ10) is shown by a solid line. As shown in the experimental results, even when an ethylene glycol aqueous solution is used, the vertical circular tube has excellent boiling cooling characteristics in the region of low heat flux. The experimental results shown in FIGS. 13 and 14 also show that the circular duct (42) of this embodiment allows cooling fins (31)
It can be confirmed that the cooling characteristics of the cooling system, especially when the heat load is small, are improved. Next, FIG. 15 is a sectional view of a cooling fin of a boiling cooling device according to a second embodiment of the third invention, and shows a cross section corresponding to FIG. 12 of the first embodiment. In this embodiment, a rectangular duct (43) with a rectangular cross section is used as the internal flow path, and thereby the same effect as in the above embodiment can be obtained. FIG. 17 is a cross-sectional view of the cooling fin of the boiling cooling device according to the example, and is a cross-sectional view taken along the line CC in FIG. is provided with a plurality of fins (44) extending in the vertical direction.These fins (44) form an internal flow path 45) at the center of the cooling fin (31). In this example, the generated air bubbles (26) are
4) and rises in the center of the cooling fin (31), the critical heat flux of the endothermic surface (31a) increases, making it difficult to dry out. Furthermore, FIG. 18 is a sectional view of a main part of a boiling cooling device according to a fourth embodiment of the third invention, and FIG. 19 is a sectional view taken along line DD in FIG. 18. In the figure, the element (41) is provided with a large number of two-stage rectangular ducts (46) as internal flow paths extending in the vertical direction. The wall thickness between each two-stage rectangular duct (46) is 2
■It is as follows. Figure 20 shows a two-stage rectangular duct (46
) is an enlarged perspective view showing a two-stage rectangular duct (46
A large number of heat transfer promoting fine particles (47) are fixed to the surface of . The heat transfer promoting fine particles (47) are made of small pieces of aluminum or copper, for example. Even with such a two-stage rectangular duct (46), the same effects as in each of the above embodiments can be obtained. Furthermore, as shown in FIG. 18, even when the liquid level of the cooling liquid (25) is below the upper end of the endothermic surface (31a), the generated air bubbles (26) flow inside the two-stage rectangular duct (46). By rising, the cooling liquid (25) also flows into the two-stage rectangular duct (46).
Due to such a pumping effect, which is pushed up inside and boils out from the upper end of the two-stage rectangular duct (46), the entire endothermic surface (31a) is cooled, and efficient boiling cooling is performed. Furthermore, the structural strength is strengthened by using the two-stage rectangular duct (46). Also, when the two-stage rectangular duct (46) is used, the fin efficiency is relatively poor, so the heat absorption surface (31a) 21 is a cross-sectional view of the boiling cooling device according to the fifth embodiment of the third invention, and is similar to FIG. 18. A cooling fin (31) having a two-stage rectangular duct (43) is used.The lower end of the first header (24b) is connected to a common liquid reservoir (33).
A bellows (48) serving as a duct is connected between the first header (24b) and the cooling fin (31).
are connected by. Typically, the cooling fins (31) are supported on the stack (12) of thyristor elements (3), and the condenser (24) is supported at another location. For this reason, cooling fins (31
) and the condenser (24) may be subject to large stresses. Further, thermal deformation may also cause undue stress on the duct. On the other hand, by using the bellows (48) in the duct portion as described above, the stress is released and the duct is prevented from breaking. In addition, in each of the above examples, pure water or an aqueous ethylene glycol solution was used as the cooling liquid (25), but
It is also possible to use other aqueous solutions or fluorocarbon solutions. Furthermore, the object to be cooled is not limited to the thyristor element (3). Further, in each of the above embodiments, one or two ducts are used, but similarly to the second invention, three or more ducts may be used, and the cross-sectional shape of the duct is not limited. Furthermore, when using two or more ducts, for example, the second
As shown in Figure 2, each duct has a bellows (48
) may be used. By the way, Fig. 23 is a cross-sectional view of a boiling cooling device using the cooling fins (31) shown in Fig. 18.
B and C each indicate the liquid level position of the coolant <25>. Figures 24 to 27 show the results (actual measurement data) of a cooling test using such a boiling cooling device. It is a relationship diagram showing the relationship between the degree of superheating and the heat flux when used at liquid level height C.For comparison, a copper horizontal disk (φ10
) and SUS vertical circular pipe (inner diameter 6mm, length 80mm) are also shown. Data for the case where Freon R113 is used as the coolant (25) is also shown. As shown in this figure, when pure water was used in the device shown in Figure 23 at a liquid level height of C, better boiling cooling characteristics were obtained compared to Freon R113 or the horizontal disk and vertical circular tube. . In addition, the following formula [1] is used to calculate the heat flux and degree of superheating.
and [2] were used. Heat flux = element power loss/endothermic area...[1]
] Degree of superheat = endothermic surface temperature - coolant temperature...
[2] FIG. 25 is a diagram showing the relationship between the degree of superheating and the heat flux when a 35 wt % ethylene glycol aqueous solution (cooling liquid) is used in the apparatus shown in FIG. 23 at a liquid level C. Similarly to FIG. 24, data for the case of using Freon R1]3, the case of a horizontal disk, and the case of a vertical circular tube are also shown. As shown in this figure, good boiling cooling characteristics were also obtained when the ethylene glycol aqueous solution had a two-circle height C. FIG. 26 is a relationship diagram arranging the results of the cooling test for the device shown in FIG. 23 in terms of the relationship between boiling heat transfer coefficient and heat flux;
This is data when pure water 1 ethylene glycol aqueous solution (20 wt%, 35 wt%) and Freon R113 were used as the coolant (25) at the liquid level height C. Also,
For comparison, horizontal disk data is also shown. This figure shows that when pure water or an aqueous ethylene glycol solution is used in the apparatus shown in FIG. 23, a high boiling heat transfer coefficient can be obtained over a wide heat flux range. FIG. 27 is a relationship diagram showing the relationship between the liquid level position and the parallel thermal resistance when an ethylene glycol aqueous solution (35 wt %) is used in the apparatus shown in FIG. 23. Also, the heat load is 100O
It is W. The parallel thermal resistance, which indicates the cooling characteristics of the cooling fins (31), is good when the liquid level position is in the range of A' to C.
If the liquid level is lower than A', the amount of exposure of the endothermic surface (31 m) from the liquid level will be large, and if the liquid level is higher than C, the amount of exposure of the heat absorbing surface (31 m) from the liquid level will be greater.
This is because this becomes a resistance to the movement of the bubbles (26). As a result of the experiment, the position of the liquid level is 1 from the upper end of the endothermic surface (31a).
A position above 0xz is appropriate, and efficient boiling cooling can be performed thereby. Hereinafter, an embodiment of the invention according to claim (4) (hereinafter abbreviated as the fourth invention) will be described with reference to the drawings. FIG. 28 is a sectional view of a boiling cooling device according to an embodiment of the fourth invention, and the same or equivalent parts as in FIG. 8 are given the same reference numerals, and their explanations are omitted. In the figure, the cooling fins (31), which are evaporators, and the condenser (24) are directly connected by a steam pipe (49).On the other hand, there are multiple Liquid cooling cooler (5) with two fin tubes (50a)
0) are connected. In other words, the liquid cooling cooler (50)
is for each duct (34), (3,5) and common liquid reservoir (3).
3) to the cooling fins (31). Note that the other configurations are the same as those shown in FIG. 8. In the boiling cooling device configured as described above, when the heat load is small, convection occurs in the cooling liquid (25) as shown by the arrows in the figure. This convected cooling liquid (25) flows into the liquid cooling cooler (50) and is cooled. Therefore, even when cooling is mainly performed by convection, that is, when the heat load is small, sufficient cooling efficiency can be obtained. In addition, in the above embodiment, an air-cooled type having a fin tube <50a) is shown as the liquid-cooling cooler (50), but the liquid-cooling cooler (50) may be any type as long as it can cool the cooling liquid. There is no particular limitation.Also, in the above embodiment, the liquid cooling cooler (50) is connected to the common liquid reservoir (33), but it may be directly connected to the cooling fins (31). Although an immersion-type boiling cooling device is shown, the present invention can also be applied to an immersion-type device.Hereinafter, examples of the invention according to claim (5) (hereinafter referred to as the fifth invention) will be described. will be explained with reference to the figures. Fig. 29 is a cross-sectional view of the evaporator of the boiling cooling device according to the first embodiment of the fifth invention, and Fig. 30 is a cross-sectional view taken along the line EE in Fig. 29. In the figure, a cooled body (52), which is a heat generating element such as a thyristor element or a power transistor, is joined to the outer peripheral surface of an evaporator (51) made of a copper block. Inside the evaporator (51), there are a first refrigerant flow path (53) with a rectangular cross section and three second refrigerant flow paths (53) with a square cross section.
4) is provided. The second refrigerant flow path (54) is
It is located closer to the object to be cooled (52) than the first refrigerant flow path (53), and is provided in parallel to the first refrigerant flow path (53). Further, the cross-sectional area of the second refrigerant flow R (54) is smaller than the cross-sectional area of the first refrigerant flow path (53). These first and second refrigerant channels (53), (
54), through which a cooling liquid such as water flows. On the inner wall surface of the object to be cooled (52) (11) of the first refrigerant flow path (53), metal particles 55, which are heat transfer promoting particles, are fixed to the minus side. A refrigerant inlet (56) is provided at one end of the evaporator (51), and a refrigerant outlet (57) is provided at the other end, each of which is connected to a condenser.Next, the operation will be described. When the object to be cooled <52> generates heat, the heat is conducted to the evaporator (51>) and cooled by the cooling liquid in the second refrigerant flow path (54).At this time,
If the heat load is small, it will be cooled by convection heat transfer, and if the heat load is large, it will be cooled by boiling heat transfer. However, when the heat load becomes even larger, the small-diameter second refrigerant flow N (54) reaches a burnout point, causing dryout of the heat transfer surface and sharply deteriorating the cooling characteristics. In such a case, heat is transferred to the first refrigerant flow path (53) having a larger diameter than the second refrigerant flow path (54), and the first refrigerant flow B
Boiling cooling is performed by the cooling liquid in (53). Normally, such heat transfer to the coolant does not occur independently, but is determined by the heat flux determined by the amount of heat flowing into the heat transfer surface and the area of the heat transfer surface. Heat, heat transfer where convection and boiling coexist, etc. are determined mutually. In particular, when the second refrigerant flow path (54) dries out, the total heat load is reduced to the first refrigerant flow 1 (53). , and the heat flux on the heat transfer surface of the first refrigerant flow IN (53) increases rapidly.In this way, in the above embodiment, before being cooled in the first refrigerant flow path (53), Since the second refrigerant flow path (54) has a smaller diameter than the first refrigerant flow path (53), cooling characteristics are obtained when the heat load is relatively small, that is, when the power loss of the object to be cooled (51) is small. On the other hand, when the heat load increases, cooling is performed in the first refrigerant flow path (53), so overall the cooling characteristics improve over a wide range of heat loads. In the above embodiment, the metal particles (55) are fixed on the heat transfer surface of the first refrigerant flow path (53), that is, on the inner wall surface, so that the surface area of the heat transfer surface is increased and the development of a temperature boundary layer is prevented. heat transfer is promoted, and as a result, the cooling efficiency, especially when the heat load is relatively large, is improved. The cooling characteristics will be explained with reference to Fig. 31. Fig. 31 is a relationship diagram showing the relationship between the degree of superheating and the heat flux of the device of the above embodiment, that is, the boiling curve. In the figure, passing through points E, F, and A The solid line indicates metal particles (5
5) and boiling curves in the case of using only the first refrigerant flow path (53) without using the second refrigerant flow path (54). In particular, point 'A' is the burnout point at this time. By adding metal particles (55) from this state, the boiling curve becomes a solid line and a broken line passing through points E, F, C, and B.9 Furthermore, by adding a second refrigerant flow path (54), The boiling curve rises to the EF point, moves to the C point, and as a whole, C,
A dashed-dotted line and a broken line pass through point B. In this way, the metal particles (55
), heat transfer is promoted and cooling efficiency is improved, especially when there is a large heat load. Furthermore, when the heat load is small, the smaller the cross-sectional area of the refrigerant flow path, the better the cooling characteristics, so the second refrigerant flow path (54)
By providing this, cooling characteristics are improved, especially when the heat load is small. Here, for example, the object to be cooled such as a power transistor is
Since the power loss often changes over time depending on the conditions in which it is used, cooling devices are required to have highly efficient cooling characteristics at all times, from small power losses to large power losses. On the other hand, the evaporator (51
), the second refrigerant flow path (54)
Since both the metal particles and the metal particles <55) are provided, the cooling efficiency can be increased over a wide range of heat loads, and excellent cooling characteristics can be obtained. Next, FIG. 32 is a cross-sectional view of the evaporator (51) of the evaporative cooling device according to the second embodiment of the fifth invention, FIG. 33 is a cross-sectional view along the F-Fill of FIG. 32, and FIG. G- in Figure 32
FIG. 3 is a cross-sectional view taken along Gli. In the figure, a reinforcing plate (58) extending in the length direction is provided at the center in the width direction of the first refrigerant flow path (53), so that two first refrigerant flow paths (53>) are provided. The object to be cooled (52) is joined to both sides of the evaporator (51), so that the second refrigerant flow path (54) is connected to the first refrigerant flow F#1 (53). The metal particles (55) are also fixed to both the upper and lower surfaces of the inner wall surface of the first refrigerant channel (53) as shown in FIG. 32. The same effect as in the example is produced.Furthermore, since the thyristor element is pressed against the evaporator (51) with a large force of about 3 tons, in this example, a reinforcing plate (58) is provided from the viewpoint of strength against pressure contact. Note that the cross-sectional shape of the second refrigerant flow path (54) is not limited to a square as shown in FIG. 29 or a circle as shown in FIG. 32, but may be other polygons, ellipses, etc. Also,
The cross-sectional shape of the first refrigerant flow path (53) is also not limited to a rectangle. Further, the object to be cooled (52) is not limited to a thyristor element or a power transistor, and the number thereof is not particularly limited either. Furthermore, first and second refrigerant channels (53), (54)
The arrangement relationship and number of the parts are not limited to those in each of the above embodiments, and the arrangement and number may be as shown in FIGS. 35 to 37, for example. Furthermore, although metal particles (55) are shown as heat transfer promoting particles in the above embodiments, for example, small pieces of aluminum or copper may be used. Further, the heat transfer promoting particles may be non-metallic particles, but particles with high thermal conductivity are preferable. Furthermore, the heat transfer promoting particles are added to the evaporator (51
) is particularly easy to fix. Further, in the above embodiment, the evaporator (51) is made of copper, but it may be made of other materials such as aluminum. Further, in the above embodiment, the metal particles (55) are fixed to the first refrigerant flow N (53), but they may be fixed to the second refrigerant flow path <54>. Furthermore, in the above embodiment, the metal particles (55) are provided all over the wall surface of the first refrigerant flow path (53) on the object to be cooled (52> side, but they may be provided on a part of the wall surface. It may also be provided on other wall surfaces. Also, in the above embodiments, water is shown as an example of the cooling liquid, but it may also be an aqueous solution such as an ethylene glycol aqueous solution or a fluorocarbon liquid.Furthermore, each of the above embodiments Although the metal particles (55) are provided in the first refrigerant flow path (53), the heat transfer promoting particles do not necessarily need to be provided, and the effects of the present invention can be obtained even if the heat transfer promoting particles are omitted. Hereinafter, an embodiment of the invention according to claim (6) (hereinafter referred to as the sixth invention) will be described with reference to the drawings. Fig. 38 shows an individual cooling fin type according to the first embodiment of the sixth invention. Figure 39 is a cross-sectional view of the cooling fin in Figure 38, and the same or equivalent parts as in Figure 5 are given the same reference numerals and their explanations are omitted. In the figure, a layer of heat transfer promoting particles (61) is fixed to each of the two heat absorbing surfaces (31a) which are heat transfer surfaces in the cooling fins (31) that are the evaporator. In addition, the cooling liquid (25) is made of pure water or an aqueous ethylene glycol solution.In such a boiling cooling device, when the heat transferred to the cooling fins (31) exceeds a predetermined value, Heat transfer accelerating particles (61
) Bubbles (26) are generated all over the space from the gap between the holes and the endothermic surface (31).
As it rises, it also rises itself. And bubbles 26
) reaches the upper part in the cooling fins (31), moves along the duct 32) to the common liquid reservoir <33), and enters the first header (24b) from the liquid level. This causes steam (27) to flow inside the first header (24b).
is full. This steam 27) is air-cooled in the condenser (24) and condensed and liquefied. The condensed liquid returns to the common liquid reservoir (33) again due to gravity and is cooled. By the way, in a device using conventional Freon R113,
The inner wall surface of the cooling fins (31) was roughened by shot blasting etc. to promote heat transfer, but when using pure water or ethylene glycol aqueous solution with different physical properties as the cooling liquid (25), conventional equipment In contrast, in the above embodiment, the heat transfer surface (3
1a) By providing the heat transfer promoting particles (61>) on the heat transfer surface (31a), heat transfer from the heat absorption surface (31a) to the cooling liquid (25) is promoted, and bubbles (26) are easily generated over the entire surface during boiling. 40 is a sectional view of a cooling fin (31) showing a second embodiment of the sixth invention, in which heat transfer promoting particles (61) are added to two
It is stuck to the layer. Furthermore, FIG. 41 is a sectional view of a cooling fin (31) showing a third embodiment of the sixth invention, in which the structural strength of the cooling fin (31) is increased by providing a reinforcing plate (62). That is, when pure water or an aqueous ethylene glycol solution is used as the coolant (25), a sufficiently developed nucleate boiling phenomenon occurs at 10'W, unlike in the case of Freon R113.
/w” or more. Therefore, for the same heat load, the smaller the area of the endothermic surface (31a), the larger the heat flux.For this reason, the heat flux of the endothermic surface (31a) ) It may be better not to provide fins to increase the heat transfer area on the surface of the cooling fins (31).In this case, the cooling fins (31) lack structural strength, so a reinforcement plate (62) is required The same effects as in the first embodiment can be obtained in these second and third embodiments. However, even when such heat transfer promoting particles (61) are used, sufficient heat transfer may not be achieved depending on the particle size. Therefore, the optimum particle size of the heat transfer promoting particles <61> when using pure water or ethylene glycol aqueous solution as the cooling liquid (25) as described above will be explained. The optimum particle size is estimated using the calculation formula shown in Proceedings of the Japan Society of Mechanical Engineers, No. 451, Part B, ``Nucleate Boiling Thermopressure Characteristics of Porous Heat Transfer Surfaces.'' The physical property values necessary for this estimation are as follows:
These are the latent heat of vaporization, surface tension, and density of refrigerant vapor, and values corresponding to the saturation temperature to be examined were used. In a non-uniform temperature field, the heat transfer surface temperature difference ΔTK required to generate bubbles from a heat transfer surface having a cavity with an opening radius recIl is given by equation [3]. However, σ: surface tension (kg/x) L: latent heat of vaporization (kca I/kg) ρV: density of refrigerant vapor (k
g/ 1) Ts: Saturation temperature of refrigerant ("C) Kc: Constant gc: Conversion coefficient. Also, g c = 10'dyne-ci + / J = =
It is 427kgf 1/meal. Furthermore, on a porous surface, cavities formed between particles are considered to form an effective bubble-like structure, and if the size of this cavity (opening radius re) is proportional to the particle diameter, then the relationship expressed by equation [4] get. rc=Kp-rp ・・・・・・【4】However, Kp
: constant rp; particle radius (stroke). From the above equations [3] and [4], the following equation [5] can be obtained. It will be done. 0.094≦Kp-ΔT/Kc≦0.23-・
-・- [61 Substituting equation [5] into equation [6] and rearranging with respect to the particle radius r, we obtain equation [7].・ ・ ・[7] Using the above equation [7], the optimum particle diameter was estimated. The results are shown in the table below. On the other hand, low heat flux Q/s -3X 10'W/1.
The range of porous surfaces with high-performance boiling heat transfer properties at high heat flux Q/S = I
6] However, in the table, A: 25-t% ethylene glycol aqueous solution B: 35-t% ethylene glycol aqueous solution C: ethylene glycol 4
5wt% aqueous solution D: ethylene glycol solution. From the results in the table above, it can be seen that when pure water or ethylene glycol aqueous solution is used as the cooling liquid (25),
The radius range of 1) is 0.17 to 3.80. Considering the practical range within this range, the radius is 0.1
The optimum particle size of the heat transfer promoting particles (61) is about 7 to 1.0 layers, that is, 300 to 2000 Jiw. This optimum particle size range is clearly different from that of Freon R113. Next, Figures 42 to 45 show the endothermic surface (
31a) is a relationship diagram between the degree of superheat and the heat flux showing the boiling heat transfer characteristics at low pressure, and FIG. The figure shows the case where two layers are laminated with a particle size of 1000 μL, FIG. 44 shows the case where the particle size is 400 μm and one layer is laminated, and FIG. 45 shows the case where two layers are laminated with a particle size of 400 μL. In addition, each figure is based on actual measured values from experiments, and for comparison, a horizontal disk (φ10■, liquid temperature 60℃)
Measured values for a smooth surface are also shown. As a result, each refrigerant of each particle size has heat transfer promoting particles (61).
It can be seen that by using a horizontal disk, the boiling heat transfer characteristics are significantly improved compared to the case of a horizontal disk. Fig. 46 is a relationship diagram showing the relationship between heat flux and heat transfer acceleration degree in pure water for each particle size based on the data in Figs.
FIG. 3 is a relationship diagram showing the relationship between heat flux and degree of heat transfer acceleration in a wt% aqueous solution for each particle size. From these figures, it can be seen that within the optimal particle size range of the heat transfer enhancing particles <61> described above, the degree of heat transfer promotion is excellent when the particle size is in the range of 400 to 1000 μm and the lamination is one or two layers. I can confirm that there is. In particular, particle size 100 (lcz
The degree of heat transfer promotion is excellent when the lamination is made into two layers. Note that the degree of heat transfer promotion was calculated using equation [8].・ ・ ・ ・ ・[8] However, the superheat degree - the endothermic surface temperature - the refrigerant temperature. To summarize the above results, the optimum particle diameter of the heat transfer promoting particles (61) when using pure water or an aqueous ethylene glycol solution as the coolant (25) is 300 to 2000 μm. And within that range 400 to ioo. The range of μm is particularly good, and it is even better if the laminated layer is two layers. In the above embodiment, an individual fin type boiling cooling device is shown, but the sixth invention can also be applied to an immersion type boiling cooling device. In this case, the heat transfer promoting particles may be fixed to a heat radiation block or the like attached to the heating element. Further, the heat transfer promoting particles (61) can be, for example, metal particles such as copper or aluminum or other non-metal particles, and are not particularly limited, but particles with high thermal conductivity are preferable. . Hereinafter, an embodiment of the invention according to claim (7) (hereinafter abbreviated as the seventh invention) will be described with reference to the drawings. FIG. 48 shows the evaporative cooling device according to an embodiment of the seventh invention, and the same or equivalent parts as in FIG. 23 are given the same reference numerals, and the explanation thereof will be omitted. In the figure, the upper end of the first header (24b) is provided with a bellows (71) that is a visible member that can be expanded and contracted. The inside of this bellows (71) contains the first header (
24b), that is, the space (7) above the liquid level of the cooling liquid (25>).
2). Thereby, the bellows (71) expands and contracts in response to pressure changes within the space (72). Further, the bellows (71) is always urged in the contraction direction by a spring (73).A movable contact (74a) is attached to the upper end of the bellows (71).This movable contact (74a) is moved by the expansion and contraction of the bellows (71), and the opposing fixed contact (
74b). Each contact (74a), (74b
) is connected to a detector (75) that detects an abnormal increase in pressure in the space (72). An alarm (76) is connected to this detector (75). These bellows (71), spring (73), each contact (
74a), (74b), detector (75) and alarm (7
6), a monitoring means (70) is configured. A vacuum container (78) serving as exhaust means is connected to the side of the first header (24b) via a solenoid valve (77). The solenoid valve (77) is connected to the detector (75) and opens when the detector (75) detects an abnormality. In the boiling cooling device configured as described above, the boiling cooling operation is similar to the device shown in FIG. 23. Here, as explained in the embodiment of the first invention, the cooling liquid (2
When using pure water or an aqueous ethylene glycol solution as 5), the saturation pressure in the operating temperature range (around 60° C.) of the thyristor element (3) will be lower than atmospheric pressure (Figure 4). Therefore, non-condensable gas such as air may enter the space (72) due to leakage. In this way, if air enters the device, the condenser (24
), the cooling performance of the cooling fluid (25) becomes high, and the temperature of the cooling fins (31) also becomes high due to this influence. When the junction temperature of the thyristor element (3) increases and exceeds the allowable temperature, the thyristor element (3)
3) will no longer function. In particular, in the case of an iris device mounted on a railway vehicle, if the function stops, the vehicle must be stopped, which will impede commercial operation. On the other hand, in the device of the above embodiment, when the pressure in the space (72) increases due to the intrusion of air, the spring (73)
The bellows (71) extends against the When the pressure rise reaches a set value, the movable contact (74m) comes into contact with the fixed contact (74b), and the abnormal pressure rise is detected by the detector (75). As a result, an alarm is issued by the alarm device (76>) and the solenoid valve (77) is opened. By opening the solenoid valve (77), the gas in the space (72) moves to the vacuum container (78). As a result, the space part (7
2) The pressure inside is reduced. When the internal pressure of the device decreases, the bellows (71) contracts and the contacts (74a) and (74b)
opens again, and when the contacts (74a) and (74b) open, a normal signal is output from the detector (75) and the solenoid valve (7
7) closes. Such a function of the monitoring means (70) and the vacuum container (78) prevents the cooling performance from deteriorating due to leakage, so that the apparatus can continue to be used. Therefore, the cooling performance of the device can be stably ensured over a long period of time. By the way, the operating temperature of the coolant (25) is determined by the heat load caused by the thyristor element (3) and the cooling performance of the condenser (24).
℃, the vapor pressure P at that time is: When using pure water as the coolant (25), the vapor pressure P = 150zyH
g (= 0.2AI?/cz2abs), cooling liquid (
When using 35 wt% ethylene glycol aqueous solution as 25), vapor pressure P=129ziHg (=0.17
ag/c1abs). On the other hand, the pressure receiving area of the bellows (71) is Se1, the spring (7
3) The spring constant is kAfI/CL, and the atmospheric pressure is P. When the displacement amount of the movable end of the spring (73) when the coolant (25) is at 60° C. is ΔXcw, the following formula [9] holds true. P 1s = P -8+ kΔX ... ... [
9] Here, if atmospheric air leaks into the device, the internal pressure of the device, that is, the vapor pressure P, increases by ΔPAg/a1, and the bellows (71) expands by ΔX, then the following equation [10] stands firm. p, -s = <p + ΔP)S+k(ΔX-Δx+
)・ ・ ・ ・ ・[10] Substituting equation [9] into equation [10] and rearranging, ΔP-S
−, Δx, = 0, that is, ΔX+=ΔP− for a pressure increase of ΔP
A displacement I of 8/k (cm) will be detected. For this reason, if the allowable value for the increase in the internal pressure of the device is determined in advance and the distance between the contacts (74m) and (74b) is set to a corresponding length, an alarm will be issued in the event of an abnormal pressure rise as described above. At the same time, the pressure in the space (72) is reduced. In addition, in the above embodiment, a thyristor element (
Although the case 3) has been described, the object to be cooled is not particularly limited as in each of the above inventions. Further, although the above embodiment shows an individual fin type (non-immersion type) boiling cooling device, the present invention can also be applied to an immersion type. Furthermore, in the above embodiment, the vacuum vessel (78
), but other devices such as a vacuum pump may also be used. Furthermore, the monitoring means (70) is not limited to the configuration of the above embodiment. Examples of the invention according to claims (8) to (10) will be described below. FIG. 49 is a diagram showing the relationship between the degree of superheat and the heat flux, showing the boiling curve of each refrigerant when the saturated liquid temperature is 1so° C., which the inventors found through experiments. The refrigerant is pure water 7% ethylene glycol 20t%
They are an aqueous solution, a 35 wt% ethylene glycol aqueous solution, and a 45 wt% ethylene glycol aqueous solution. It can be seen that for each refrigerant, the boiling curve changes when the heat flux is around 105 W/1. Here, the actual measured values (degree of superheating ΔTsat, heat flux Q/S steam pressure Ps and heat transfer coefficient α) and the physical property values of each refrigerant when the saturated liquid temperature is 60°C (thermal conductivity Kl, surface tension σ , the specific gravity of the liquid ρ1, the specific gravity of the vapor ρ, the Brunttl number Pr of the liquid, the latent heat of vaporization of the refrigerant, and the temperature conductivity al of the liquid) are expressed by the following formulas of the Nusselt number Nu and dimensionless number F [11] ~ [13
] and organized the experimental results. q α=3. ΔT, t (W/1°C) ・(12) ・ ・ ・ ・ ・ [13] For example, for a 35 wt% ethylene glycol aqueous solution, the relationship between the Nusselt number Nu and the dimensionless number F, which is the relationship of nucleate boiling heat transfer. Fig. 50 shows the arrangement of
The formula of e (N u = 7.OX 10-' -F ) is
The broken line represents the empirical formula created by the inventor for ethylene glycol 35-1% (N u = 9.Ox 1o-' -
F) are shown respectively. Dimensionless numbers (Nu, F)
Most of the measured values arranged in the above are arranged in the range of -25% to +40% with respect to the inventor's experimental formula. but,
When the dimensionless number F is 2×10' or less, the above-mentioned measured values exhibit characteristics that deviate from the inventor's experimental formula. This shows that the characteristics of the 35 wt% ethylene glycol aqueous solution as a refrigerant are divided into a region where the nucleate boiling transfer characteristic is strong and a region where it is slightly weak (a region where nucleate boiling and natural convection are mixed). The figure is a relationship diagram showing the relationship between the mixing ratio of the ethylene glycol aqueous solution and the heat flux at the stable nucleate boiling WGN point, and the actual values are shown for each of the saturated liquid temperatures of 40°C, 60°C, 70'C, and 80'C. This figure shows that the heat flux at the start point of stable nucleate boiling is affected by the mixing ratio and saturated liquid temperature. Figure 52 shows the relationship between the mole fraction m of ethylene glycol and the start of boiling. It is a relationship diagram showing the relationship between the F value of a point and the mole fraction m and F
To summarize the relationship with the values, the following formula [10% formula % [14] Using this formula [10], from the mole fraction m of ethylene glycol, the F value at the boiling start point corresponding to that mole fraction can be calculated. You can ask for it. On the other hand, the heat flux q/s is determined by the following equation [15].・ ・ ・ ・ ・ [15] Therefore, if the heat transfer area S of the evaporator is determined so that F in equation [15] is greater than or equal to the F value at the boiling start point determined by equation [10], The evaporator of a boiling cooling device using an aqueous ethylene glycol solution can be used at a heat flux value higher than the boiling start point as shown in FIG. In addition, when using a fluorocarbon-based coolant, as a result of the dimensionless arrangement of the inventors' experimental results, the F value for determining the heat flux at the boiling start point is F = 1.1X10'
was gotten. Similarly, when using pure water or an aqueous solution as the coolant, F = 2.7X 10' was obtained. Here, q/s: heat flux value (W/i2)q
: Heat amount (W> S : Heat transfer area of evaporator (1> L : Latent heat of vaporization <keal/kg>ρV
; Specific weight of vapor (ktt/1) ρ1 : Specific weight of liquid (Ay/1) aj = Temperature conductivity of liquid
(1/hr) σ: Surface tension (Ag/position) Ps: Steam pressure (kg/1) Pr: Prandtl number of liquid (->) Organizing the above results, the following relational expression is given for each refrigerant: Pure water or aqueous solution F≧2.7x 104 Fluorocarbon refrigerant F≧1.1xlO' Ethylene glycol aqueous solution F≧2.IX 10'・m-0O') Once the heat transfer area is determined, a heat flux higher than the boiling starting point as shown in FIG. 53 can be used, and a practically stable boiling state can be obtained. That is, it is possible to obtain an evaporator with stable cooling performance without fluctuations in the degree of superheating. [Effects of the Invention] As explained above, the boiling cooling device of the invention according to claim (1) uses a cooling liquid made of an ethylene glycol aqueous solution and a copper condenser, so it can be used without using fluorocarbons. Moreover, it is possible to obtain excellent cooling performance while preventing performance deterioration due to corrosion. In the boiling cooling device of the invention according to claim (2), since the evaporator is connected to the common liquid reservoir through a duct oriented in a substantially horizontal direction, the height dimension can be reduced. This has the effect of making it possible to downsize and lower the floor of the equipment to which this device is attached. In the boiling cooling device of the invention according to claim (3), the evaporator is connected to the common liquid reservoir through a duct oriented in the horizontal direction, and upper and lower Since a plurality of internal flow paths extending in the direction are provided, in addition to the effect of the invention of claim (2), bubbles in the cooling liquid can easily move, so cooling by boiling and convection can be efficiently performed. , the boiling cooling characteristics are improved. In the boiling cooling device of the invention according to claim (4), the liquid cooling cooler is connected to the evaporator and the convected cooling liquid is cooled. This has the effect of increasing efficiency, thereby improving cooling characteristics when the heat load is small, and providing excellent cooling characteristics as a whole. In the evaporative cooling device of the invention according to claim (5), since the second refrigerant flow path having a smaller cross-sectional area than the first refrigerant flow path is provided in the evaporator, cooling characteristics are particularly good when the heat load is small. This results in the effect that excellent cooling characteristics can be obtained over a wide range of heat loads. In the boiling cooling device of the invention according to claim (6), a large number of heat transfer promoting particles having a particle size of 300 μm or more and 2000 μm or less are fixed on the heat transfer surface in the evaporator, so that heat transfer is effectively promoted. This has the effect that excellent cooling performance can be obtained using a cooling liquid made of water or an aqueous ethylene glycol solution without using fluorocarbons. The boiling cooling device of the invention according to claim (7) is provided with a monitoring means facing the space for monitoring the pressure in the space above the liquid level of the cooling liquid, and also reduces the pressure in the space when the pressure rises abnormally. Since the exhaust means is connected to the space, it is possible to prevent deterioration of cooling performance due to leakage, and as a result, it is possible to obtain excellent cooling performance with a cooling liquid made of water or ethylene glycol aqueous solution without using Freon. This has the effect of stabilizing performance over a long period of time. In the boiling cooling device of the invention according to claims (8), (9) and (10), the heat transfer area of the evaporator is set to a heat flux value equal to or higher than the boiling point m of the refrigerant. This has the effect of preventing fluctuations in the degree of superheating and stabilizing cooling performance.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing the first embodiment of the first invention, Fig. 2 is a diagram showing the relationship between the degree of superheating of the heat transfer surface and the heat flux showing the boiling curve of each refrigerant, and Fig. 3 is a diagram showing the boiling curve of each refrigerant. FIG. 4 is a relationship diagram showing the relationship between ethylene glycol concentration and freezing temperature, and FIG. 4 is a relationship diagram showing the relationship between saturated liquid temperature and saturated pressure of each refrigerant. 5 is a block diagram showing the first embodiment of the second invention, FIG. 6 is a front view of FIG. 5, FIG. 7 is a sectional view showing the second embodiment of the second invention, and FIG. 2 A sectional view showing a third embodiment of the invention,
FIG. 9 is a sectional view showing a fourth embodiment of the second invention. FIG. 10 is a partially cutaway sectional view showing the first embodiment of the third invention, FIG. 11 is a sectional view taken along line A-Ai4i in FIG. 10, and FIG. 12 is a sectional view taken along line BB in FIG. 10. 13 is a relationship diagram showing the boiling curve of a vertical circular tube when pure water is used as a refrigerant, and FIG. 14 is a diagram showing the boiling curve of a vertical circular tube when an aqueous ethylene glycol solution is used as a refrigerant. 15 is a sectional view showing the second embodiment of the third invention; FIG. 16 is a sectional view showing the third embodiment of the third invention;
7 is a sectional view taken along line C-C in FIG. 16, FIG. 18 is a sectional view showing the fourth embodiment of the third invention, and FIG.
8 is a sectional view taken along line D-D in FIG. 8, FIG. 20 is an enlarged perspective view of the two-stage rectangular duct in FIG. 18, and FIG. 21 is a sectional view showing the fifth embodiment of the third invention. , FIG. 22 is a sectional view showing the sixth embodiment of the third invention, FIG. 23 is a sectional view of a boiling cooling device using the cooling fins of FIG. Figure 25 shows the relationship between the degree of superheating and heat flux when the liquid is used at a liquid level of C. Figure 25 shows the degree of superheating when an aqueous ethylene glycol solution is used in the apparatus of Figure 23 at a liquid level of C. Fig. 26 is a relational diagram showing the relationship between boiling heat transfer coefficient and heat flux, Fig. 26 is a relational diagram arranging the results of the cooling test for the device in Fig. 23 in terms of the relationship between boiling heat transfer coefficient and heat flux, and Fig. 27 is a relational diagram showing the relationship between
4 is a relationship diagram showing the relationship between the liquid level position and the parallel thermal resistance when an ethylene glycol aqueous solution is used in the apparatus shown in FIG. 3. FIG. FIG. 28 is a sectional view showing one embodiment of the fourth invention. FIG. 29 is a sectional view showing the first embodiment of the fifth invention.
The figure is E-E! in Figure 29! 31 is a relationship diagram showing the boiling curve of the device in FIG. 29, FIG. 32 is a sectional view showing the second embodiment of the fifth invention, and FIG. -Fli, FIG. 34 is a sectional view taken along line GG in FIG. 32, and FIG. 35 is a sectional view taken along line GG in FIG.
A sectional view showing the embodiment, FIG. 36 is H-)(l
A cross-sectional view along arrow i, FIG. 37 is arrow 1 along I-I@ in FIG. 35! FIG. FIG. 38 is a sectional view showing the first embodiment of the sixth invention;
The figures are a sectional view of the cooling fin shown in FIG. 38, FIG. 40 is a sectional view showing the second embodiment of the sixth invention, FIG. 41 is a sectional view showing the third embodiment of the sixth invention, and FIGS. Figure 45 is a relationship diagram showing the boiling heat transfer characteristics of the endothermic surface when pure water or ethylene glycol aqueous solution is used as the coolant, and Figure 42 shows the particle size of the heat transfer promoting particles with one layer of 1000μLWt. In this case, Fig. 43 shows the case where the particle size is 1000 μL and the lamination is made into two layers, Fig. 44 shows the case where the particle size is 400 μL and the lamination is made into one layer, and Fig. 45 shows the case where the particle size is 400 ux and the 81F layer is made into two layers.
Each case is shown as a layer. Figure 46 is the 42nd
A relationship diagram showing the relationship between heat flux and heat transfer promotion degree in pure water for each particle size based on the data in Figures 4-45.
FIG. 7 is a relationship diagram showing the relationship between heat flux and degree of heat transfer acceleration in a 35 wt% ethylene glycol aqueous solution for each particle size. FIG. 48 is a configuration diagram showing an embodiment of the seventh invention. Figure 49 is a diagram showing the relationship between the degree of superheat and heat flux, showing the boiling curve of each refrigerant when the saturated liquid temperature is 60°C, and Figure 50 is the F value and N value showing the nucleate boiling heat transfer of a 35 w% ethylene glycol aqueous solution.
Figure 51 is a diagram showing the relationship between the mixing ratio of an aqueous ethylene glycol solution and the heat flux at the stable nucleate boiling point, and Figure 52 is a diagram showing the relationship between the molar fraction of ethylene glycol and the F value. FIG. 53 is a diagram showing the relationship between the degree of superheat and the heat flux, which shows the boiling curve of a general refrigerant. Fig. 54 is a configuration diagram showing an example of a conventional immersion type device;
Figure 5 is a configuration diagram showing an example of a non-immersion type conventional device, No. 56.
The figure is a relationship diagram between degree of superheat and heat flux showing a boiling curve of a general refrigerant. In the figure, (3) is the thyristor element (cooled body), (
21) is the evaporator, (22> is the steam pipe (steam flow path), (2
3) is a liquid return pipe (liquid return flow path), (24) is a condenser, (
25) is the cooling liquid, (31> is the cooling fin (evaporator), <
31m) is the heat transfer surface, (32> is the duct, (33) is the common liquid reservoir, (42) is the circular duct (internal flow 1), <43>
is a rectangular duct (internal flow path), (45> is an internal flow path, (4
6> is a two-stage rectangular duct (internal flow path), (48) is a bellows (duct), (50> is a liquid cooling cooler, (51)
is the evaporator, (53> is the first refrigerant flow path, (54> is the second
The refrigerant 7XN, (61) are heat transfer promoting particles, (70) is a monitoring means, and (71> is an exhaust means. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (10)

[Claims] (1) It is characterized by being equipped with an evaporator containing a cooling liquid made of an aqueous ethylene glycol solution, and a copper condenser connected to the evaporator via a vapor flow path and a liquid return flow path. boiling cooling equipment. (2) A common liquid reservoir connected to the condenser and containing the coolant; and a common liquid reservoir connected to the common liquid reservoir via a duct, containing the coolant, and covered with and an evaporator joined to a cooling body, wherein the duct is oriented substantially horizontally and the evaporator is arranged to the side of the common liquid reservoir. A boiling cooling device characterized by: (3) A common liquid reservoir connected to the condenser and containing the cooling liquid, and connected to the common liquid reservoir via a duct and joined to the object to be cooled; and an evaporator containing a cooling liquid, wherein the duct is oriented substantially horizontally, and the evaporator is arranged to the side of the common liquid reservoir. A boiling cooling device characterized in that the evaporator has a plurality of internal channels extending in the vertical direction inside the endothermic surface of the evaporator. (4) It is characterized by being equipped with an evaporator connected to the condenser and accommodating a coolant, and a liquid cooling cooler connected to the evaporator and cooling the inflowing coolant. boiling cooling equipment. (5) In a boiling cooling device including an evaporator connected to a condenser and containing a cooling liquid, the evaporator includes a first refrigerant flow path and a first refrigerant flow path. An evaporative cooling device characterized in that a second refrigerant flow path having a smaller cross-sectional area than the refrigerant flow path is provided in parallel with each other. (6) In a boiling cooling device equipped with an evaporator connected to a condenser and containing a cooling liquid, the cooling liquid consists of either water or an aqueous ethylene glycol solution, and the cooling liquid is contained in the evaporator. A boiling cooling device characterized in that a large number of heat transfer promoting particles having a particle diameter of 300 μm or more and 2000 μm or less are fixed on the heat transfer surface of the device. (7) an evaporator containing a coolant made of either water or an aqueous ethylene glycol solution; a condenser connected to the evaporator to condense vapor of the coolant; and a liquid level of the coolant. monitoring means provided facing the upper space and monitoring the pressure in the space; connected to the space;
A boiling cooling device comprising: exhaust means for reducing the pressure inside the space when the pressure abnormally increases. (8) In a boiling cooling device equipped with an evaporator connected to a condenser and containing a cooling liquid, the cooling liquid consists of pure water or an aqueous solution, and the heat transfer area of the evaporator A boiling cooling device characterized in that satisfies the relational expression shown below. F≧2.7×10^4 However, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ q/s: Heat flux value (W/m^2) q: Amount of heat (W) s: Heat transfer area of the evaporator (m ^2) L: Latent heat of vaporization (kcal/kg) ρv: Specific weight of vapor (kg/m^3) ρl: Specific weight of liquid (kg/m^3) al: Temperature conductivity of liquid (m^2/ hr) σ: Surface tension (kg/m) Ps: Steam pressure (kg/m^2) Pr: Prandtl number of liquid (-) (9) In a boiling cooling device equipped with an evaporator connected to a condenser and containing a cooling liquid, the cooling liquid is made of an ethylene glycol aqueous solution, and the heat transfer area of the evaporator is A boiling cooling device characterized by satisfying the relational expression shown below. F≧2.1×10^4・m^-^0^. ^0^2^γHowever, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ q/s: Heat flux value (W/m^2) q: Amount of heat (W) s: Heat transfer area of the evaporator (m^2) L: Latent heat of vaporization (kcal/kg) ρv: Specific weight of vapor (kg/m^3) ρl: Specific weight of liquid (kg/m^3) al: Temperature conductivity of liquid (m^2/hr) σ : Surface tension (kg/m) Ps: Steam pressure (kg/m^2) Pr: Prandtl number of liquid (-) m: Molar fraction of ethylene glycol (10) In a boiling cooling device equipped with an evaporator connected to a condenser and containing a fluorocarbon-based cooling liquid, the heat transfer area of the evaporator satisfies the relational expression shown below. A boiling cooling device featuring: F≧1.1×10^4 However, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ q/s: Heat flux value (W/m^2) q: Amount of heat (W) s: Heat transfer area of the evaporator (m ^2) L: Latent heat of vaporization (kcal/kg) ρv: Specific weight of vapor (kg/m^3) ρl: Specific weight of liquid (kg/m^3) al: Temperature conductivity of liquid (m^2/ hr) σ: Surface tension (kg/m) Ps: Steam pressure (kg/m^2) Pr: Prandtl number of liquid (-)