JP2007251085A - Cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase cooling capacity by cooling water using a simple structure. <P>SOLUTION: A semiconductor element 10 is placed on a substrate 11, a heat exchange part 30 whose internal surface is coated with resin is prepared on a reverse surface of the substrate 11, and the coolant water from a cooling water tank 6 is circulated from a plunger pump 2 to the heat exchange part 30, thus cooling the semiconductor element 10. In response to the temperature of the semiconductor element 10 detected by a temperature sensor 13, a volume of air controlled by a rate-of-flow control valve 8 is supplied to the plunger pump 2, and the air is pressurized in the pump and dissolved into the cooling water, thus augmenting the air dissolved amount in the coolant water in case the temperature is high. Since this produces minute air bubbles of a nano scale near the wall surface coated with resin in the heat exchange part 30, a pressure loss due to friction between the wall surface and the cooling water is reduced, an amount of heat carried by the cooling water becomes larger, and the cooling capacity is increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling device that cools a heating element by circulating a cooling liquid.

Conventionally, for example, in a semiconductor power conversion device that converts power between input and output power systems, a cooling device that cools heat generated in a power semiconductor element as a heating element with a refrigerant is disclosed in RE-Table 00/017927.
This is because, when continuously operated with a constant cooling capacity, the temperature of the power semiconductor element rises and falls due to the load fluctuation of the power converter, and this becomes a heat cycle, leading to a decrease in the life and reliability of the power semiconductor element. The flow rate of the refrigerant is continuously variably controlled according to the temperature of the element.
Thereby, the heat cycle is reduced, and the effect of improving the reliability and life is obtained.
No. 00/017927

By the way, although the cooling action is due to heat transfer between the refrigerant and the wall surface supporting the power semiconductor element, the refrigerant that has received heat from the power semiconductor element side moves quickly, new refrigerant arrives, and heat transfer continues. Without it, high cooling efficiency cannot be expected.
In this regard, when the heating element is cooled by circulation of liquid as a refrigerant, conventionally, it is said that the flow velocity of the liquid becomes 0 (zero) in the vicinity of the wall surface, and there is a limit to improving heat transfer. It was thought.
In view of the above-described conventional problems, an object of the present invention is to provide an improved cooling device in which heat transfer between a wall surface on a heating element side and a cooling liquid is further improved.

Dreck. C. According to Tretheway's experiment, when the material of the channel is not wetted by the liquid and the liquid that has not been degassed is passed through the channel, the velocity of the liquid in the vicinity of the channel wall is not zero, Confirmed to have speed.
This phenomenon does not occur when the channel wall surface is wetted by the liquid, and does not occur even if the liquid is degassed.
He says that this phenomenon is due to nanoscale micro-bubbles generated near the channel wall. (Reference, “Simulation of fluid slip at 3D hydrophobic microchannels by the lattice Boltzmnn method” Journal of Computational Physics 2021 (2005) 2021).

His experiment was carried out on a liquid flowing in a minute flow path, but the present invention applies this phenomenon to cooling by liquid circulation to cool the heating element more efficiently.
That is, the present invention includes a heat exchanging unit attached to the heating element, and a circulation unit that circulates a cooling liquid in the heat exchanging unit, and cooling the heating element according to the temperature of the heating element. Gas dissolved amount control means for increasing / decreasing the gas dissolved amount in the liquid is provided, and the flow path in the heat exchange section has a wall surface that is liquid repellent with respect to the cooling liquid.

  According to the present invention, by increasing the amount of dissolved gas in the cooling liquid supplied to the heat exchange unit according to the temperature rise of the heating element, nano-scale micro bubbles are generated near the wall surface of the heat exchange unit, Since the pressure loss due to friction between the wall surface and the cooling liquid is reduced, the amount of heat carried by the cooling liquid is increased, and the cooling capacity can be increased.

Next, embodiments of the present invention will be described by way of examples.
FIG. 1 shows an overall configuration of a cooling device according to a first embodiment applied to cooling a power conversion switch using a semiconductor element, a CPU or the like (hereinafter, referred to as a semiconductor element as a representative).
In the cooling device 1, the semiconductor element 10 is placed on the substrate 11, and a heat exchanging unit 30 through which cooling water flows is provided on the back surface of the substrate 11. Further, a temperature sensor 13 made of, for example, a thermocouple is attached to the semiconductor element 10, and the temperature sensor 13 is connected to the control unit 14.
One end of the heat exchange unit 30 is connected to the plunger pump 2 via a pipe 5c, and the other end is connected to the cooling water tank 6 via a pipe 5d. The cooling water tank 6 stores cooling water made of water.
A heat radiating portion 16 is attached to the pipe 5d.

The plunger pump 2 includes a pump housing 21 including check valves 4a, 4b, and 4c, and a plunger 20 that is disposed in the pump housing 21 and forms a plunger chamber 22 between the pump housing 21. The The plunger 20 reciprocates in the pump housing 21 in the vertical direction in FIG. 1, and the volume of the plunger chamber 22 changes as the plunger 20 reciprocates.
The plunger chamber 22 is connected to the pipe 5a through the check valve 4a, and is connected to the bottom of the cooling water tank 6 through the check valve 4b and the pipe 5b.
The pipe 5a is provided with a flow control valve 8, and the other end of the pipe 5a is opened to the atmosphere.
The pipe 5c connected to the heat exchange unit 30 is connected to the plunger chamber 22 of the pump housing 21 through the check valve 4c.

The check valve 4a only allows air to be sucked into the plunger chamber 22 from the pipe 5a, and prevents backflow to the outside.
The check valve 4b allows only the intake of the cooling water from the cooling water tank 6 to the plunger chamber 22, and prevents the reverse flow to the outside.
The check valve 4c allows only discharge from the plunger chamber 22 to the pipe 5c side and prevents backflow.
When the plunger 20 moves downward in FIG. 1, the check valves 4a and 4b are opened with the check valve 4c closed, and the cooling water through the air from the pipe 5a and the pipe 5b from the cooling water tank 6 is opened. Are sucked into the plunger chamber 22.
When the plunger 20 moves upward in FIG. 1, the check valve 4c opens with the check valves 4a and 4b closed, and the cooling water in the plunger chamber 22 is discharged to the pipe 5c. Thereby, the cooling water is pumped by the reciprocating motion of the plunger 20, and the cooling water is supplied to the heat exchange unit 30.

As shown in FIG. 2, the heat exchanging unit 30 stands parallel to each other from the upper wall 32 in surface contact with the substrate 11 to the vicinity of the lower wall 33 facing in parallel with the substrate 11 in the cross section of the flow path 31 of the cooling water. A large number of lowered fins 34 are provided to increase the area of the heat transfer wall surface. 2A shows a cross section perpendicular to the flow of cooling water, and FIG. 2B shows a cross section parallel to the flow of cooling water.
The heat exchanging portion 30 is preferably made of metal from the viewpoint of heat transfer, and the inner wall surface including the upper wall 32 and the lower wall 33 and the surface of the fin 34 are subjected to a fluorine-based or silicon-based resin coating C, It is liquid repellent.
While flowing through the heat exchange unit 30, the cooling water takes heat from the substrate 11 and cools the semiconductor element 10 on the substrate 11.
The cooling water that has passed through the heat exchanging unit 30 dissipates heat taken from the substrate 11 in the heat dissipating unit 16 while flowing through the pipe 5 d, and returns to the cooling water tank 6.
By repeating the above, the cooling water circulates through the heat exchange unit 30.

Here, when cooling water is sucked from the cooling water tank 6 in the plunger pump 2, air is also supplied from the pipe 5a at the same time, so the plunger 20 moves upward in FIG. 1 and the cooling water is discharged to the pipe 5c. In the plunger chamber 22, the pressure is applied in a state where water and air coexist. As a result, air dissolves in the cooling water.
The flow control valve 8 is controlled by the control unit 14 based on the temperature of the semiconductor element 10 measured by the temperature sensor 13 and adjusts the amount of air flowing into the plunger chamber 22 through the pipe 5a. Thereby, the amount of air dissolved in the cooling water, that is, the dissolved amount of gas in the cooling water changes.
Specifically, as the temperature of the semiconductor element 10 is higher, the flow control valve 8 is controlled to the open side to increase the amount of air supplied into the plunger chamber 22 and increase the amount of dissolved gas, while the temperature is increased. As the flow rate is lower, the flow control valve 8 is controlled to the throttle side, the amount of air into the plunger chamber 22 is reduced, and the dissolved gas amount is reduced.

When the cooling water is pumped, a velocity boundary layer is formed in the vicinity of the wall surface of the flow path 31, but a large shearing force is generated in the velocity boundary layer due to the difference in the flow velocity of the liquid. When the amount of dissolved gas in the cooling water is large, a kind of reduced-pressure boiling (cavitation) occurs due to the shearing force, and the inner wall of the heat exchanging portion 30 is difficult to get wet with the cooling water by the liquid repellent resin coating C. A nanoscale minute bubble is generated in the vicinity.
Therefore, when the cooling water in which the dissolved amount of gas is increased is circulated to the heat exchanging unit 30, the pressure loss caused by the friction between the wall surface and the cooling water is reduced by the microbubbles. As a result, a non-zero flow rate of the cooling water can be obtained even near the wall surface, so that the amount of heat carried by the cooling water increases and the cooling capacity increases.

  The air that has become microbubbles returns to the cooling water tank 6 in a state separated from the cooling water, but the pipe 5b supplies cooling water to the plunger chamber 22 from the bottom of the cooling water tank 6, so that the cooling water tank 6 The returned air is not recirculated to the plunger chamber 22 again, and the amount of air to the plunger chamber 22 is controlled exclusively by the flow control valve 8 on the pipe 5a. The air returned to the cooling water tank 6 is discharged as appropriate.

In the present embodiment, the route returning from the plunger pump 2 to the plunger pump 2 through the pipe 5c, the heat exchanging portion 30, the pipe 5d, the cooling water tank 6, and the pipe 5b sequentially constitutes the circulating means in the invention. The cooling water tank 6 corresponds to the cooling liquid tank.
The semiconductor element 10 corresponds to a heating element, cooling water made of water corresponds to a cooling liquid, and air corresponds to a gas.
Moreover, the inner wall surface to which the resin coating C of the heat exchange unit 30 is applied corresponds to the liquid repellent wall surface.
Then, air is supplied to the plunger pump 2 through the flow rate control valve 8 that is adjusted by the control unit 14 in accordance with the temperature of the semiconductor element 10 detected by the temperature sensor 13, and water and air are added in the plunger pump 2. The structure that performs the pressure constitutes the dissolved gas amount control means.

The present embodiment is configured as described above, and the channel wall surface of the heat exchanging unit 30 is made liquid repellent so that it is difficult to get wet with water, and the dissolved amount of cooling water supplied to the heat exchanging unit 30 is set to the semiconductor element 10. The pressure is increased in a state where water and an amount of air corresponding to the temperature detected by the temperature sensor 13 are mixed, so that the air is dissolved in the water. As a result, nano-scale bubbles are generated in the vicinity of the wall surface in the flow path 31 of the heat exchanging unit 30 and pressure loss due to friction between the wall surface and the cooling water is reduced. Capability can be increased.
As a result, even when the flow rate of the cooling water is kept constant, it is possible to perform cooling according to the heat generation amount of the semiconductor element 10 by controlling the dissolved gas amount. This has the effect of greatly expanding the control range.

  The air can be dissolved in the cooling water before the cooling water is sucked into the plunger pump 2 or after it is discharged from the plunger pump 2, but in this embodiment, in particular, depending on the temperature of the semiconductor element 10. An apparatus for supplying cooling water by supplying air whose flow rate is controlled by the flow control valve 8 to the plunger pump 2 and simultaneously dissolving the cooling water by the plunger pump 2 by dissolving the air in the cooling water; Since there is no need to separately provide two devices for dissolving air in the cooling water, there is an advantage that the manufacturing cost and man-hours can be reduced.

Next, a second embodiment will be described.
In the first embodiment, the flow rate control valve is controlled in accordance with the temperature of the semiconductor element to change the dissolved gas amount in the cooling water. In this embodiment, however, the main liquid and the liquid having a low vapor pressure due to the reaction are used. Alternatively, nanoscale microbubbles are generated in the vicinity of the wall surface of the heat exchange section using cooling water mixed with a secondary liquid that generates gas.
In FIG. 3, the whole structure of 1 A of cooling devices in a 2nd Example is shown.
In addition, the same number is attached | subjected about the same structure as a 1st Example, and description is abbreviate | omitted.
Plunger pump 2A is not provided with check valve 4a as compared with plunger pump 2 in the first embodiment, and pipe 5a and flow control valve 8 are eliminated. Thereby, the temperature sensor 13 and the control part 14 are also unnecessary.

The cooling water tank 6A stores cooling water in which alcohol as methanol, ethanol or the like whose reaction is promoted by a catalyst as water is dissolved in water as main liquid.
As shown in FIG. 4, the heat exchanging portion 30A has the same shape as the heat exchanging portion 30 in the first embodiment, but the catalyst S is formed on the surface of the fin 34 that is lowered from the upper wall 32 on the substrate 11 side. It is carried in a shape. When Cu or an alloy containing Cu is used as the catalyst S, the reaction of alcohol with hydrogen or carbon dioxide is promoted at a relatively low temperature of about 200 ° C.
If each wall including the fins 34 of the heat exchanging portion 30A is made of the same kind of Cu as the catalyst S or made of an alloy containing Cu, the joining of the catalyst is facilitated compared with the case of using a different metal, and the thermal expansion coefficient is reduced. There is no worry about the decrease in reliability due to the difference.

The inner wall surface of the flow path 31 of the heat exchanging section 30A is provided with a fluorine-based or silicon-based resin coating C, as in the first embodiment. FIG. 4A shows a cross section perpendicular to the flow of cooling water, and FIG. 4B shows a cross section parallel to the flow of cooling water.
One end of the heat exchange unit 30A is connected to the plunger pump 2A via a pipe 5c, and the other end is connected to the cooling water tank 6A via a pipe 5d.

In the plunger pump 2A, the volume of the plunger chamber 22 changes as the plunger 20 reciprocates.
The pipe 5c connected to the heat exchange unit 30A is connected to the plunger chamber 22 of the pump housing 21 via the check valve 4c.
The plunger chamber 22 is connected to the cooling water tank 6A through a check valve 4b and a pipe 5b.
The check valve 4b only allows the cooling water to be sucked into the plunger chamber 22 from the cooling water tank 6A and prevents the reverse flow to the outside.
The check valve 4c allows only discharge from the plunger chamber 22 to the pipe 5c side and prevents backflow.

When the plunger 20 moves downward in FIG. 3, the check valve 4b opens with the check valve 4c closed, and cooling water from the cooling water tank 6A is sucked into the plunger chamber 22 through the pipe 5b. The
When the plunger 20 moves upward in FIG. 3, the check valve 4c opens with the check valve 4b closed, and the cooling water in the plunger chamber 22 is discharged to the pipe 5c. Thereby, cooling water is pumped by the up-and-down reciprocating motion of the plunger 20, and the cooling water is supplied to the heat exchange unit 30A.
Other configurations are the same as those of the first embodiment.

In the above configuration, in the heat exchanging unit 30A, the reaction is promoted by the catalyst S in which the alcohol in the cooling water is carried on the fins 34, and hydrogen and carbon dioxide are generated to increase the dissolved gas amount. As the amount of dissolved gas increases, nanoscale micro bubbles of hydrogen or carbon dioxide are generated in the vicinity of the wall surface in the flow path 31 of the heat exchange section 30A, as in the first embodiment.
Since the catalyst S is disposed in the heat exchanging portion 30A that is transferred from the semiconductor element 10 via the substrate 11, the higher the temperature of the semiconductor element 10, the more the catalytic action is activated, and the reaction amount of alcohol increases, resulting in gas Increase in dissolved amount. As a result, the amount of microbubbles generated automatically changes according to the temperature of the semiconductor element 10.

In the present embodiment, the path returning from the plunger pump 2A to the plunger pump 2A through the pipe 5c, the heat exchange section 30A, the pipe 5d, the cooling water tank 6A, and the pipe 5b sequentially constitutes the circulation means in the invention. The cooling water tank 6A corresponds to the cooling liquid tank.
The semiconductor element 10 corresponds to a heating element, and cooling water obtained by dissolving alcohol in water corresponds to a cooling liquid. In particular, the water that forms the cooling water corresponds to the main liquid, and the alcohol corresponds to the sub-liquid.
The inner wall surface to which the resin coating C of the heat exchange part 30A is applied corresponds to the liquid repellent wall surface.
The structure in which the catalyst S that promotes the reaction of alcohol is arranged in the flow path of the heat exchange unit 30A and the generation amount of hydrogen or carbon dioxide is increased or decreased by activation according to the temperature of the catalyst S constitutes the dissolved gas amount control means. ing.

The present embodiment is configured as described above, and includes, in addition to water as cooling water, alcohol that generates hydrogen, carbon dioxide, or the like having a low vapor pressure by a reaction. In addition, since the catalyst S that promotes the reaction is disposed in the flow path 31 of the heat exchange unit 30A, the gas is activated by the activation of the catalyst S according to the temperature of the semiconductor element 10 without a flow control valve or the like. The dissolved amount changes, and this allows nanoscale microbubbles to be generated near the wall surface of the heat exchanging unit 30A with a simpler structure, reducing pressure loss due to friction between the wall surface and the cooling water, and increasing the cooling capacity. Can be made.
In addition, since the catalyst S for promoting the reaction is disposed in the heat exchanging portion 30A attached to the substrate 11 on which the semiconductor element 10 as the heat source is installed, the catalyst S is promptly raised when the temperature of the semiconductor element 10 rises. Since the reaction is promoted by activation, the responsiveness is particularly high, which is advantageous for preventing overheating of the semiconductor element 10.

In this embodiment, the catalyst S such as Cu is supported on the entire surface of the fin 34 in the heat exchanging portion 30A. However, since the metal catalyst is easily wetted with water or alcohol, the arrangement of the catalyst S is heat exchanged. By limiting the inside to the upstream side as well, the fins can have a principal part as a resin coating C surface which is difficult to get wet with water or alcohol, and the area where the cooling water is not zero can be widened.
Furthermore, as long as the temperature of the semiconductor element 10 is transferred and can be sensed, the catalyst S can be disposed in the pipe 5c on the upstream side, not in the heat exchange section.

Next, a third embodiment will be described. In this embodiment, a temperature sensor is provided for the second embodiment, and the component concentration of the cooling water is adjusted in accordance with the temperature of the heating element.
In FIG. 5, the whole structure of the cooling device 1B in a 3rd Example is shown.
Note that the same components as those in the second embodiment are denoted by the same reference numerals and description thereof is omitted.
The plunger chamber 22 of the plunger pump 2 is connected to the bottom of the cooling water tank 6A through the check valve 4b and the pipe 5b, and is connected to the sub liquid tank 7 through the check valve 4a and the pipe 5a. The pipe 5a is provided with a flow rate control valve 8B.
The cooling water tank 6A stores cooling water obtained by dissolving alcohol as a secondary liquid in water as a main liquid. Alcohol is stored in the sub liquid tank 7.

The semiconductor element 10 is provided with a temperature sensor 13, and the cooling water tank 6 </ b> A is provided with a concentration sensor 18 for detecting the alcohol concentration of the stored cooling water.
The temperature sensor 13 and the concentration sensor 18 are connected to the control unit 14B, and the control unit 14B controls the flow rate control valve 8B based on the temperature of the semiconductor element 10 measured by the temperature sensor 13 and the concentration of the alcohol component detected by the concentration sensor 18. To do.
Specifically, as the temperature of the semiconductor element 10 is higher or the alcohol concentration is lower, the flow rate control valve 8B is opened to increase the amount of alcohol in the plunger chamber 22, and as the temperature is lower or the alcohol concentration is higher, the flow rate is increased. The control valve 8B is controlled to the throttle side to reduce the amount of alcohol in the plunger chamber 22.

One end of the heat exchange unit 30A is connected to the plunger chamber 22 via the pipe 5c and the check valve 4c, and the other end is connected to the cooling water tank 6A via the pipe 5d.
When the plunger 20 moves downward in FIG. 5, the check valves 4a and 4b are opened while the check valve 4c is closed, and the alcohol from the pipe 5a and the cooling water through the pipe 5b from the cooling water tank 6A are opened. Are sucked into the plunger chamber 22. When the plunger 20 moves upward in FIG. 5, the check valve 4c opens with the check valves 4a and 4b closed, and the cooling water in the plunger chamber 22 is discharged to the pipe 5c. Thereby, cooling water is pumped by the up-and-down reciprocating motion of the plunger 20, and the cooling water is supplied to the heat exchange unit 30A.
Other configurations including the internal structure of the heat exchange unit 30A are the same as those of the second embodiment.

  According to the present embodiment, as in the second embodiment, the amount of dissolved gas changes in accordance with the temperature of the semiconductor element, thereby generating nanoscale microbubbles in the vicinity of the wall surface of the heat exchanging portion 30A. The pressure loss due to the friction between the semiconductor element 10 and the cooling water can be reduced, the cooling capacity can be increased, the responsiveness to the temperature change of the semiconductor element 10 is high, and the semiconductor element 10 is prevented from overheating.

Further, the reaction promoted by the catalyst S is determined by the temperature and the concentration of the alcohol component. However, the higher the concentration, the larger the reaction amount. Therefore, the higher the temperature of the semiconductor element 10, the more the alcohol is controlled by controlling the flow control valve 8B. By supplying to the plunger chamber 22, the amount of dissolved gas increases and the cooling capacity further increases.
Note that the higher the temperature of the semiconductor element 10, the greater the reaction amount promoted by the catalyst S, and the greater the reaction amount when the concentration is increased, but as a result of the accelerated reaction, the reaction amount is returned to the cooling water tank 6A. Even if the concentration of the alcohol component in the incoming cooling water decreases, the controller 14B adjusts the flow rate control valve 8B to reflect the decrease in concentration detected by the concentration sensor. Correspondingly, it can be adjusted to an appropriate value.

  In the present embodiment, the catalyst S such as Cu is supported on the entire surface of the fin 34 using the same heat exchanging portion 30A as in the second embodiment, but depending on the temperature of the semiconductor element 10 Since the amount of dissolved gas increases or decreases by increasing or decreasing the amount of alcohol, the catalyst S is placed at an arbitrary position in the pipe 5c upstream from the heat exchanging portion and is not affected by the temperature of the semiconductor element. It can also be set as the structure which exhibits a fixed catalytic action. As a result, the entire inner wall of the heat exchanging portion 30A is made liquid repellent resin coating C surface to make it difficult to get wet with water or alcohol, and the region where the cooling water is not zero can be further expanded.

In the second and third embodiments, the main liquid and the sub-liquid that form part of the cooling water are not limited to alcohol with respect to water, and a liquid or gas having a low vapor pressure is generated by the reaction. Any combination of components can be employed as long as it is one.
Furthermore, although the cooling water is composed of two components of water and alcohol, the invention is not limited to this, and it may be three or more components as long as it contains a liquid or gas having a low vapor pressure by reaction, or A part thereof may be single-component cooling water that generates a liquid or gas having a low vapor pressure by reaction.

In each embodiment, the plunger pump 2 is used as a pump for pumping cooling water. However, the present invention is not limited to this, and other types of pumps may be used.
In the heat exchanging units 30 and 30A, the linear fins 34 from the upstream to the downstream are provided in the flow path 31 of the cooling water. However, the heat exchange units 30 and 30A are not limited to this. Arbitrary shapes can be adopted, such as a folded channel.

In addition, although the Example demonstrated the case where the heat generating body as cooling object was a semiconductor element, this invention is not limited to cooling of a semiconductor element, It can apply to cooling of various heat generating bodies.
Corresponding to the heating element, for example, also in the first embodiment, the liquid forming the cooling water is not limited to water, the gas is not limited to air, and any combination can be adopted.

It is a figure which shows the whole structure of the cooling device in a 1st Example. It is a figure which shows the detail of a heat exchange part. It is a figure which shows the whole structure of the cooling device in a 2nd Example. It is a figure which shows the detail of the heat exchange part in a 2nd Example. It is a figure which shows the whole structure of the cooling device in a 3rd Example.

Explanation of symbols

1, 1A, 1B Cooling device 2, 2A Plunger pump 4a, 4b, 4c Check valve 5a, 5b, 5c, 5d Piping 6, 6A Cooling water tank 7 Sub liquid tank 8, 8B Flow control valve 10 Semiconductor element 11 Substrate 13 Temperature sensor 14, 14B Control unit 16 Heat radiation unit 18 Concentration sensor 20 Plunger 21 Pump housing 22 Plunger chamber 30, 30A Heat exchange unit 31 Flow path 32 Upper wall 33 Lower wall 34 Fin C Resin coating S Catalyst

Claims (11)

In the cooling device for cooling the heating element, comprising a heat exchange part attached to the heating element, and a circulation means for circulating a cooling liquid in the heat exchange part,
Gas dissolved amount control means for increasing or decreasing the gas dissolved amount in the cooling liquid according to the temperature of the heating element,
The cooling device, wherein the flow path in the heat exchange section has a wall surface that is liquid repellent with respect to the cooling liquid. The gas dissolved amount control means has a temperature sensor for detecting the temperature of the heating element, pressurizes the cooling liquid and gas in an amount corresponding to the temperature of the heating element, The cooling device according to claim 1, wherein the gas dissolved amount in the cooling liquid is increased or decreased by dissolving the gas in the liquid. The circulating means has a cooling liquid tank that stores the cooling liquid, and a pump that pumps the cooling liquid from the cooling liquid tank to the heat exchange unit,
The gas dissolved amount control means supplies the gas to the pump via a flow rate control valve that controls the flow rate according to the temperature of the heating element, and pressurizes the cooling liquid and the gas in the pump. The cooling device according to claim 2. The cooling device according to any one of claims 1 to 3, wherein the cooling liquid is water and the gas is air. A part of the cooling liquid generates a liquid or gas having a low vapor pressure by a reaction,
The gas dissolved amount control means includes a catalyst that is disposed in the heat exchange section or a flow path upstream from the heat exchange section and promotes a reaction to a liquid or gas having a low vapor pressure in the cooling liquid, and the heating element. The cooling device according to claim 1, wherein the amount of dissolved gas in the cooling liquid is increased or decreased by changing the reaction amount in accordance with the temperature of the liquid. The cooling liquid includes a main liquid and a sub-liquid that generates a liquid or gas having a low vapor pressure by reaction,
The cooling device according to claim 5, wherein the catalyst generates a liquid or gas having a low vapor pressure by promoting a reaction of the sub-liquid. The said catalyst is arrange | positioned in the heat-transfer area | region from the said heat generating body, The reaction amount to the liquid or gas with a low vapor | steam pressure in the said cooling liquid is changed by activation according to temperature, The said or 5 characterized by the above-mentioned. 6. The cooling device according to 6. The gas dissolved amount control means has a temperature sensor for detecting the temperature of the heating element, and controls the amount of the sub-liquid according to the temperature of the heating element detected by the temperature sensor. The cooling device according to claim 6 or 7, wherein a reaction amount to a liquid or gas having a low vapor pressure is changed. The circulating means has a cooling liquid tank that stores the cooling liquid, and a pump that pumps the cooling liquid from the cooling liquid tank to the heat exchange unit,
Furthermore, a sub liquid tank for storing the sub liquid is connected to the pump via a flow control valve,
The gas dissolved amount control means supplies the sub liquid whose flow rate is controlled by the flow rate control valve according to the temperature of the heating element detected by the temperature sensor from the sub liquid tank to the pump. Item 9. The cooling device according to Item 8. The circulating means is configured to return the cooling liquid that has passed through the heat exchange unit to the cooling liquid tank,
Having a concentration sensor for detecting the concentration of the sub liquid in the cooling liquid of the cooling liquid tank;
The flow rate of the secondary liquid supplied to the pump by the flow rate control valve is controlled according to the concentration of the secondary liquid detected by the concentration sensor in addition to the temperature of the heating element detected by the temperature sensor. The cooling device according to claim 9. The cooling device according to any one of claims 6 to 10, wherein the main liquid is water, the sub-liquid is alcohol, and the catalyst is Cu or an alloy containing Cu.

Images