JP2015129594A - Airlift pump cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop an airlift pump cooling device capable of preventing boiling delay even if the absolute volume of refrigerant on a heat receiving surface increases.SOLUTION: An airlift pump cooling device comprises a heat receiver having a heat receiving surface in contact with a heating element and refrigerant is filled in the heat receiver. Bubbles are generated by boiling the refrigerant in the heat receiver by the heating element and the refrigerant in the heat receiver as well as the bubbles are transported upward in a direction of gravitational force via a first channel. The heat of the refrigerant fed via the first channel is drawn in a radiator. The refrigerant cooled in the radiator is transported via a second channel back to the heat receiver. A gas-liquid separator is provided halfway along the first and second channels for condensing the bubbles generated in the heat receiver by transferring the heat of the refrigerant in the first channel to the refrigerant in the second channel. The gas-liquid separator also functions as a first preheating unit preheating the refrigerant cooled in the radiator. Furthermore, a second preheating unit is provided for preheating the refrigerant preheated in the first preheating unit just before the refrigerant is boiled.

Description

  The present invention relates to a bubble pump type cooling device to which a natural circulation liquid cooling system is applied.

  Cooling devices applied to power converters used in generators, electric vehicles, etc., meet the recent demands for low environmental impacts, and the boiling devices typified by bubble pump type cooling devices using a natural circulation liquid cooling system Cooling technology with a heat transport form using latent heat is applied.

Japanese Patent Laid-Open No. 2005-245566

  However, in a cooling device having a heat transport mode that uses the latent heat of boiling, when it is applied to a device with a large heat transfer area, the absolute volume of the refrigerant on the heat receiving surface increases. It took time to.

  The bubble pump type cooling device according to the embodiment includes a heat receiver having a heat receiving surface in contact with the heating element. The heat receiver is sealed in a state filled with refrigerant. Then, the refrigerant in the heat receiver is boiled by the heating element to generate bubbles, and the refrigerant in the heat receiver is conveyed upward along with the bubbles through the first flow path in the gravity direction. The refrigerant conveyed through the first flow path is deprived of heat by the radiator. The refrigerant cooled by the radiator is conveyed through the second flow path and refluxed to the heat receiver. In the middle of the first flow path and the second flow path, there is a gas-liquid separator that condenses the bubbles generated in the heat receiver by transferring the heat of the refrigerant in the first flow path to the refrigerant in the second flow path. Is provided. This gas-liquid separator also functions as a first preheating unit that preheats the refrigerant cooled by the radiator. Furthermore, a second preheating unit is provided that further preheats the refrigerant that is in thermal contact with the heat receiver and preheated in the first preheating unit.

FIG. 1 is a schematic view of a bubble pump type cooling device according to the first embodiment. FIG. 2 shows the bubble pump type cooling device of the second embodiment in which a check valve is provided in the middle of the flow path of the bubble pump type cooling device of FIG. FIG. 3 is an enlarged cross-sectional view of the heat receiver of FIG. 4 cut along F3-F3. FIG. 4 is a partially enlarged view of the heat receiver of FIG. 1 as viewed from the direction of the heating element. FIG. 5 is an enlarged cross-sectional view of the heat receiver of FIG. 1 cut along F5-F5. FIG. 6 is an enlarged cross-sectional view showing a modified example of the heat receiver in FIG. 1. FIG. 7 is another enlarged cross-sectional view showing a modification of the heat receiver of FIG. FIG. 8 is another enlarged cross-sectional view showing a modification of the heat receiver of FIG.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  The bubble pump type cooling device 1 (hereinafter simply referred to as the cooling device 1) according to the first embodiment is, for example, a cooling device that cools a heating element such as a semiconductor element applied to a system that constitutes a power conversion device. Applied. For example, the cooling device 1 is installed on a substantially vertical plane in the housing (not shown). The size of the cooling device 1 is appropriately adjusted according to the conversion loss amount with respect to the output capacity of the power conversion device, and the amount of the refrigerant 11 enclosed in the cooling device 1 is also appropriately adjusted according to the size.

  FIG. 1 is a diagram schematically illustrating the overall configuration of the cooling device 1 according to the first embodiment. In FIG. 1, the gas-liquid separator 4 is a cross-sectional view for explaining the double tube structure. The cooling device 1 has a heat receiving surface 12 that is in contact with the heating element 7 and has the heat receiving device 2 in which the refrigerant 11 is enclosed, and the heat of the refrigerant 11 conveyed from the heat receiving device 2 through the first flow path 5. It has a radiator 3 to be taken away. Between the heat receiver 2 and the heat radiator 3, there is a first flow path 5 that conveys the refrigerant 11 in the heat receiver 2 together with the bubbles 13 generated by the boiling of the refrigerant 11 toward the heat radiator 3 in the gravitational direction. Is provided. The refrigerant 11 cooled by the radiator 3 is returned to the heat receiver 2 through the second flow path 6. A gas-liquid separator 4 having a double pipe structure is provided in the middle of the first flow path 5 and the second flow path 6. The double pipe structure refers to a pipe structure in which the inner pipe is arranged in a double manner so that heat conduction is possible with the first flow path 5 and the outer pipe as the second flow path 6.

  Next, each part of bubble pump type cooling device 1 concerning Embodiment 1 is explained in detail.

  As shown in FIGS. 4 and 5, the heat receiver 2 is a vertically long and flat container with a bottom, and a roof-type cover 29 that narrows toward the first flow path 5 and the second flow path 6 at the top thereof ( Upper wall). The roof type cover 29 has an outlet 27 connected to the first flow path 5 and an inlet 28 (FIG. 3) connected to the second flow path 6 at the upper part of the roof type cover 29. The heat receiving surface 12 is provided outside the first side wall 20 a of the heat receiver 2. On the heat receiving surface 12, a heating element 7 as a heat source is disposed in contact with the heat receiving surface 12 so that heat can be conducted. The heat receiving surface 12 conducts the heat received from the heat generator 7 to the inside of the heat receiver 2 and cools the heat generator 7. At this time, the refrigerant 11 is heated.

  Although the semiconductor element is mentioned as the heat generating body 7 which contacts the heat receiving surface 12 of the heat receiver 2, it is not restricted to this. As shown in FIG. 4, the heating elements 7 are arranged on the heat receiving surface 12 side by side in the direction of gravity with a certain interval in two rows. About arrangement | positioning of the heat generating body 7, the arrangement | positioning to the heat receiving surface 12 should just be determined according to the emitted-heat amount of the heat generating body 7 mounted, and the magnitude | size of the heat generating body 7. FIG. Moreover, as a material used for the heat receiver 2 having the heat receiving surface 12, for example, aluminum, copper, or the like is used according to the type of the refrigerant 11 used. Further, the heat receiving surface 12 may be subjected to external treatment such as irradiation beam, sand blasting and thermal spray coating to improve the surface properties.

FIG. 3 is an enlarged cross-sectional view of the heat receiver 2 of FIG. 4 cut along F3-F3.
The heat receiver 2 includes side walls 20 a and 20 b having a roof type cover 29 connecting the first flow path 5 and the second flow path 6, a bottom wall 26, and a heat receiving surface 12 connecting the roof type cover 29 and the bottom wall 26. , 20c, 20d. Further, the internal space of the heat receiver 2 is divided into a heat receiving space 24 that communicates with the first flow path 5 and a preheating space 25 that communicates with the second flow path 6, and a partition wall 22 that extends in the gravitational direction that divides these spaces. have. A gap 23 that communicates the preheating space 25 and the heat receiving space 24 is provided between the bottom end of the partition wall 22 in the gravity direction and the bottom wall 26. In addition, the 2nd preheating part provided in the heat receiver 2 is called the preheating space 25. FIG.

  The refrigerant 11 is conveyed below the heat receiver 2 along the partition wall 22 in the preheating space 25. The refrigerant 11 heated in advance in the first preheating unit 4 and refluxed to the heat receiver 2 receives heat from the partition wall 22, the roof type cover 29, and the side walls 20 b, 20 c, and 20 d and is heated to near the boiling point in this transport process. That is, the partition wall 22, the roof cover 29, and the side walls 20b, 20c, and 20d that are members surrounding the preheating space 25 function as a second preheating portion. The refrigerant 11 heated to near the boiling point passes through a gap 23 provided below the partition wall 22 and is conveyed to the heat receiving space 24.

  In the heat receiving space 24, when the refrigerant 11 is further heated by the heat from the heating element 7 and reaches the boiling point, boiling starts and bubbles 13 are generated. Buoyancy acts due to the density difference between the bubbles 13 and the surrounding refrigerant 11, and an upward flow is induced. With this upward flow, the surrounding refrigerant 11 also follows the bubbles 13 and rises in the heat receiving space 24 and is conveyed to the first flow path 5. In addition, the flow of the refrigerant | coolant 11 at this time will be in the mixed state of a gaseous phase and a liquid phase, ie, the state of a gas-liquid two-phase flow.

  The material used for the partition wall 22 is not particularly limited, but is appropriately determined in consideration of the type of refrigerant used, the heat conduction performance from the heat receiving space 24 to the preheating space 25, and the like. For example, as with the heat receiver 2, aluminum, copper, or the like is used. Here, as for the relationship between the partition wall 22 and the gap 23, if the refrigerant 11 conveyed from the preheating space 25 to the heat receiving space 24 is sufficiently heated to the state before boiling and the delay of boiling does not occur, the gap 23 The tip shape and size are not questioned.

  Specifically, in the first embodiment, heat is transmitted to the partition wall 22 via the refrigerant 11 in the heat receiving space 24. The temperature of the refrigerant 11 in the preheating space 25 increases as it goes toward the lower end of the partition wall 22. The temperature of the refrigerant 11 is adjusted so that the refrigerant 11 is conveyed to the heat receiving space 24 over the gap 23 before boiling. Therefore, the height of the gap 23 from the lower end of the partition wall 22 to the bottom wall 26 is adjusted in the range of the distance from the lower end of the heating element 7 disposed at the lowest position of the heat receiving surface 12 to the bottom wall 26. At this time, the material and size of the heat receiver 2, the material and thickness of the partition wall 22, the type of the refrigerant 11, the temperature of the recirculated refrigerant 11, and the like are also taken into consideration.

  FIG. 5 is an enlarged cross-sectional view of the heat receiver of FIG. 1 cut along F5-F5. As shown in FIG. 5, on the heat receiving space 24 side of the partition wall 22, a plurality of rectifying plates 21 arranged at equal intervals in the direction of gravity are provided. By arranging the current plate 21, the bubbles 13 generated by boiling are conveyed along the current plate 21 upward in the gravity direction. In order to increase the flow rate of the refrigerant 11, a roof type cover 29 is provided in which the flow path narrows toward the first flow path 5. The interval between the rectifying plates 21 can be adjusted according to the amount of heat generated by the heating element 7 in contact with the heat receiving surface 12 or the heat flux caused by the size of the heat receiving unit 2. The number is not limited to 21. In FIG. 5, a plurality of rectifying plates 21 extending in the vertical direction are arranged. However, the rectifying plates 21 may be arranged obliquely so as to converge toward the first flow path 5a.

  As shown in FIG. 1, the first flow path 5 is a flow path that extends above the heat receiver 2 and is connected to the radiator 3. The first flow path 5 conveys the gas-liquid two-phase flow of the bubbles 13 and the refrigerant 11 generated in the heat receiving space 24 to the radiator 3. A gas-liquid separator 4 is provided in the middle of the first flow path 5. The refrigerant 11 in the gas-liquid two-phase flow state inside the first flow path 5 changes its flow mode from the gas-liquid two-phase flow state to the single-phase flow state in the gas-liquid separator 4 by condensing the bubbles 13 in the refrigerant. To do. The refrigerant 11 that has changed to a single-phase flow state (that is, a liquid phase) is conveyed from the first flow path 5 to the radiator 3 and is returned to the heat receiver 2 through the second flow path 6. The second flow path 6 is a flow path that extends from the outlet of the radiator 3 through the gas-liquid separator 4 to the inlet 28 of the preheating space 25.

  As shown in FIG. 1, the gas-liquid separator 4 has a double tube structure, and heat exchange is performed via the wall of the first flow path 5. The gas-liquid separator 4 is provided with a first flow path 5 provided between the heat receiver 2 and the radiator 3 as a flow path inside the double tube structure. On the other hand, the 2nd flow path 6 after passing through the heat radiator 3 was provided as a flow path of the outer side of a double tube structure. The second flow path 6 outside the gas-liquid separator 4 shown in the first embodiment has a cylindrical shape whose sectional diameter is about twice that of the first flow path 5. The refrigerant 11 conveyed inside the second flow path 6 passes through the radiator 3 and then flows in from the upper inlet 41 of the flow path outside the gas-liquid separator 4 and is provided at the lower outlet 42. Spilled from. The flow direction of the refrigerant 11 flowing through the inner first flow path and the refrigerant 11 flowing through the outer side are opposite directions. In addition, the refrigerant | coolant 11 conveyed through the inside of the 1st flow path 5 and the 2nd flow path 6 is not mixed.

  Although the gas-liquid separator 4 of Embodiment 1 is represented by a double pipe structure, the structure is not limited to this structure, and the bubbles 13 of the refrigerant 11 in the inner first flow path are condensed, and the outer first The refrigerant 11 flowing through the two flow paths 6 may be heated. For example, the structure (not shown) etc. which arrange | position the 2nd flow path around the inside 1st flow path in the shape of a coil in the axial direction may be sufficient.

  As described above, the refrigerant 11 conveyed through the first flow path 5 is a gas-liquid two-phase flow including the bubbles 13 in front of the gas-liquid separator 4. On the other hand, the refrigerant 11 conveyed through the second flow path 6 after passing through the radiator 3 is different from the refrigerant 11 in the first flow path 5 as compared with the refrigerant 11 in the first flow path 5. Low temperature single phase flow. And the refrigerant | coolant 11 sent into the heat receiver 2 is heated up slightly from the refrigerant | coolant 11 immediately after having come out of the heat radiator 3. FIG. That is, the gas-liquid separator 4 functioning as the first preheating unit preheats the refrigerant 11.

  The refrigerant 11 flowing inside the first flow path 5 is cooled by heat moving to the refrigerant 11 flowing inside the second flow path 6 located outside in the gas-liquid separator 4. Thereby, the bubble 13 in the refrigerant | coolant 11 which flows through the inside of the 1st flow path 5 condenses, and changes to a single phase flow. On the other hand, the refrigerant 11 conveyed inside the second flow path 6 located outside is heated by receiving heat from the refrigerant 11 flowing through the first flow path 5. In other words, the gas-liquid separator 4 functions as a first preheating part by sensible heat transport using the temperature difference of the refrigerant 11 flowing through the first flow path 5 and the second flow path 6.

  As shown in FIG. 1, the radiator 3 is provided along a third flow path 32 located between the first flow path 5 and the second flow path 6. As shown in FIG. 1, the third flow path 32 is folded back in a U shape. The heat radiating plate 31 of the radiator 3 is provided with holes for passing the third flow path 32, and a plurality of holes are arranged at regular intervals. The third flow path 32 is disposed so as to pass through the heat radiating plate 31 twice. The plurality of heat sinks 31 are disposed substantially parallel to each other, and are fixed to the third flow path 32 by welding or the like. Thereby, the heat of the refrigerant 11 flowing through the third flow path 32 is released from the radiator 31 to the outside air to cool the refrigerant 11. In order to increase the cooling efficiency, a fan 8 is provided at a position facing the radiator 3. The number of piping inside the radiator 3, the number of radiator plates, the size of the fan, and the like are adjusted according to the required cooling performance.

  That is, the refrigerant 11 cooled by the radiator 3 needs to be preheated in the first preheating unit 4 and the preheating space 25 and heated up to the point of boiling. Therefore, the cooling amount of the refrigerant 11 in the radiator 3 determines a state in which the maximum effect can be exhibited in consideration of the balance with the preheating performance in the first preheating unit 4 and the preheating space 25. The maximum effect here means that the refrigerant 11 returned to the heat receiver 2 boils immediately after passing through the gap 23 and can start latent heat transport, and generates the most bubbles in the heat receiving space 24. It refers to the state that can be done. In addition, in Embodiment 1, although the case of the air cooling type is shown as the heat radiator 3, it is good also as a water cooling type by installing a water jacket in the position of the heat radiator 3. FIG.

  As described above, in the first embodiment, the recirculating refrigerant 11 is first preheated in the gas-liquid separator 4 (first preheating portion), and the preheating space 25 (first) provided inside the heat receiver 2. In the 2 preheating section), the second preheating is further given. By using this two-stage preheating system, the refrigerant 11 can be transported to the heat receiving space 24 in a state in which the refrigerant 11 is more likely to boil (low subcool degree).

  For this reason, even when the cooling device 1 of the first embodiment is applied to a large heat transfer area, the refrigerant 11 in the heat receiver 2 is sufficiently heated in the first preheating unit 4 and the preheating space 25 before the subcool degree. Is conveyed to the heat receiving space 24 in a low state. Thereby, since boiling is started immediately after the gap 23 is exceeded, the boiling is not delayed in the heat receiving space 24. Furthermore, since the refrigerant 11 flows into the heat receiving space 24 in a state where the subcooling degree is low, the amount of the generated bubbles 13 is increased to promote boiling, and the rising force of the bubbles 13 can be increased.

  As the refrigerant 11 used in the first embodiment, a generally chemically stable material such as pure water, hydrocarbon-based, aqueous ammonia solution, antifreeze liquid, heat storage microcapsule, nanofluid, etc. is used. Those having low latent heat of vaporization, thermal conductivity and viscosity coefficient, and those having little toxicity even if leaked and having nonflammability are desirable. Furthermore, in view of recent considerations for environmental performance, those having a low ozone depletion potential (ODP) and global warming potential (GWP) are also desirable.

  Next, the bubble pump type cooling device 10 (hereinafter referred to as the cooling device 10) according to Embodiment 2 will be described.

  FIG. 2 is a schematic diagram of the overall configuration of the cooling device 10 according to the second embodiment. In FIG. 2, the gas-liquid separator 4 is a cross-sectional view for easy understanding of the double tube structure. In addition, the same code | symbol is attached | subjected about the component similar to Embodiment 1. FIG. Moreover, since the movement path | route in the cooling device 10 of the refrigerant | coolant 11 is the same as that of Embodiment 1, it abbreviate | omits about this description.

  As shown in FIG. 2, the cooling device 10 according to the second embodiment is different from the first embodiment in that the check valve 9 a is provided in front of the radiator 3 that is the terminal portion of the first flow path 5. It has been. The check valve 9 a is provided in such a direction as to open in the delivery direction from the gas-liquid separator 4 to the radiator 3. In addition, a check valve 9 b is provided in front of the inlet 28 of the second flow path 6. The check valve 9b is provided in such a direction as to open in the delivery direction from the outlet 42 of the gas-liquid separator 4 to the inlet 28 of the second preheating unit 25. Since the configuration other than this portion is the same as that of the cooling device 1 of the first embodiment, description of the configuration that functions in the same manner is omitted here.

  The check valves 9a and 9b act effectively when steady circulation of the refrigerant 11 is difficult. The case where it is difficult to circulate the refrigerant 11 constantly means that the boiling state of the refrigerant 11 inside the heat receiver 2 is intermittent, for example, when the apparatus is cooled such that the output fluctuation is large and the thermal load is biased. When it is easy to become.

  For example, in a power conversion device for solar power generation or wind power generation, due to fluctuations in sunshine hours or changes in wind direction, the thermal load fluctuations of the semiconductor elements used are relatively large, and the thermal load tends to be biased. . For this reason, it is assumed that the boiling state inside the heat receiver 2 becomes intermittent and it becomes difficult to circulate the refrigerant 11 constantly.

  Even in the above case, since the cooling device 10 is provided with the check valves 9 a and 9 b, the refrigerant 11 in the first flow path 5 and the second flow path 6 returns to the heat receiver 2. And the backflow of the refrigerant 11 is prevented.

  On the other hand, when the heating element 7 starts to generate heat again and heat is transmitted to the heat receiving space 24 through the heat receiving surface 12, and the generation of the bubbles 13 from the refrigerant 11 starts, the refrigerant 11 is caused to flow through the first flow by the rising force of the bubbles 13. It flows into the gas-liquid separator 4 through the path 5. When the bubbles 13 are condensed in the gas-liquid separator 4 and heat exchange is started, the refrigerant 11 passes through the check valve 9 a and is conveyed to the radiator 3. Simultaneously with the opening of the check valve 9a, the check valve 9b is also opened from the viewpoint of preserving the momentum in the second flow path 6, and the circulation flow of the refrigerant 11 is started.

  By arranging the check valves 9a and 9b, since the flow of the refrigerant 11 is restricted in one direction, the temperature difference in the flow path of the refrigerant 11 can be reduced, and thus intermittent boiling is suppressed. In addition, the circulation of the refrigerant 11 in the cooling device 1 can be stabilized.

  The positions of the check valves 9a and 9b in the cooling device are provided in consideration of the operating differential pressure so that the pressure loss head of the entire system is lower than the natural circulation driving head.

  As described above, the cooling devices 1 and 10 provided with the first preheating unit 4 and the second preheating unit 25 can maintain a low subcooling state in the latent heat transport inside the heat receiver 2. Therefore, not only the boiling delay does not occur, but also the amount of bubbles generated in the heat receiving space 24 increases, so that the ascending force of the refrigerant 11 is increased and the circulation flow rate of the refrigerant 11 in the circulation flow path is improved. As a result, when it is considered to dissipate heat under the same heat flux, the heat transfer area of the heat receiving surface 12 can be reduced, and finally the size and manufacturing cost of the cooling devices 1 and 10 can be reduced. It is what.

  Next, modified examples of the second flow path 6 and the heat receiver 2 will be described with reference to FIGS.

FIG. 6 is a cross-sectional view of a modification of the heat receiver 2 and the second flow path 6 returning to the heat receiver 2.
The heat receiver shown in FIG. 6 includes a first side wall 20 a having an upper wall 29 (FIG. 4) connected to the first flow path 5, a bottom wall 26, and a heat receiving surface 12 connecting the upper wall 29 and the bottom wall 26. And a heat receiving space 24 in which the first flow path 5 communicates with the internal space of the heat receiver 2. The second flow path 6 is disposed along the longitudinal direction of the heat receiver 2. A plurality of branched second flow paths 6a, 6b,..., 6n including the outlet of the second flow path 6 are provided on the second side wall 20b facing the heat receiving surface 12.

  The second flow path 6 and the heat receiver 2 are connected to each other through branch second flow paths 6a, 6b,. That is, a part of the second flow path 6 functions as the second preheating unit 25. In addition, as shown in FIG. 8, you may contact the 2nd flow path 6 and the heat receiver 2 directly. About the contact area of the 2nd flow path 6 and the heat receiver 2, it can adjust suitably with the amount of preheating required for the refrigerant | coolant 11 which circulates through the inside of the 2nd flow path 6. FIG.

  The branched second flow paths 6a, 6b,... 6n connected to the heat receiver 2 are branched into a plurality of pipes in accordance with the positions facing the heating elements 7 arranged on the heat receiving surface 12 of the heat receiver 2. It is installed on the second side wall 20b. Therefore, each branch 2nd flow path 6a, 6b ... 6n is in the position where the refrigerant | coolant 11 discharged | emitted from the discharge port is sprayed on the contact surface of each heat generating body 7 arrange | positioned at the heat receiving surface 12 of the 1st side wall 20a. Fixed.

  As another modification, as shown in FIG. 7, the branched second flow paths 6 a, 6 b,..., 6 n are substantially conical nozzle-shaped injection ends whose front ends are penetrated into the heat receiver 2. 61. Thereby, the local flow velocity of the refrigerant 11 is increased and sprayed to the contact surface of the heating element 7. For this reason, from the effect of the jet on the heat receiving surface 12, reducing the thickness of the temperature boundary layer due to overheating in boiling leads to a significant improvement in heat transfer coefficient. The number of the branched second flow paths 6a, 6b,... 6n arranged in parallel is appropriately adjusted according to the size, arrangement pattern, number, and heat generation amount of the heating elements 7 attached to the heat receiving surface 12.

  The flow rate of the refrigerant 11 sent out from the branched second flow paths 6a, 6b... 6n increases as it approaches the bottom wall 26 of the heat receiver 2. For this reason, for example, the flow rate of the refrigerant 11 discharged from the branched second flow path 6n positioned below the gravity direction is larger than the flow rate of the refrigerant 11 discharged from the branched second flow path 6a. However, the refrigerant 11 discharged from the lower branched second flow path 6c where the flow rate increases is sufficiently preheated in the process of being conveyed through the second flow path 6 arranged along the heat receiver 2. For this reason, it is in the state which can be boiled immediately after discharge | emission from the branch 2nd flow path 6c. On the other hand, the refrigerant 11 discharged from the branched second flow path 6a in the upstream portion of the second flow path 6 has a short preheating distance, but in addition to a small discharge amount, the refrigerant 11 directly toward the heating element 7 is used. It is adjusted so that it does not take time to boil. If the upper local flow velocity does not increase, the nozzle 61 may be attached only to the branched second flow path 6a.

  As shown in FIGS. 6, 7 and 8, the preheating space for the second preheating portion 25 is heat-received by branching the second flow path 6 and injecting the refrigerant 11 into the heat-receiving space 24. Since it is not necessary to provide in the inside of a container, it becomes possible to design the heat receiver 2 thinly. Furthermore, by making the heat receiver 2 thin, the absolute volume of the refrigerant 11 to be used can be reduced. Then, by reducing the thickness of the heat receiver 2 and reducing the refrigerant 11 used, the entire apparatus can be downsized.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various changes, replacements, and changes can be made without departing from the scope of the invention.
These embodiments and modifications thereof are included in the scope of the invention as well as included in the scope and spirit of the invention.

DESCRIPTION OF SYMBOLS 1 ... Bubble pump type cooling device, 10 ... Bubble pump type cooling device, 11 ... Refrigerant, 12 ... Heat receiving surface, 2 ... Heat receiving device, 20a, 20b, 20c, 20d ... Side wall, 21 ... Rectifying plate, 22 ... Bulkhead, 23 ... Gap, 24 ... Heat receiving space, 25 ... Second preheating part, 26 ... Bottom wall, 27 ... Outlet, 28 ... Inlet, 29 ... Roof type cover, 3 ... Heat radiator, 31 ... Heat sink, 32 ... Third Flow path, 4 ... Gas-liquid separator (first preheating part), 41 ... Inlet, 42 ... Outlet, 5 ... First flow path, 6 ... Second flow path, 6a ... Branched second flow path, 6b ... Branch 2nd flow path, 6n ... Branch 2nd flow path, 61 ... Injection end, 7 ... Heat generating body, 8 ... Fan, 9a ... Check valve, 9b ... Check valve, 13 ... Bubble.

Claims (8)

A heat receiver having a heat receiving surface in contact with the heating element and having a refrigerant sealed therein;
A first flow path that conveys the refrigerant in the heat receiver together with bubbles generated by the boiling of the refrigerant in the heat receiver in the direction of gravity;
A radiator that takes heat away from the refrigerant conveyed through the first flow path;
A second flow path for returning the refrigerant cooled by the radiator to the heat receiver;
In the middle of the first and second flow paths, by transferring the heat of the refrigerant passing through the first flow path to the refrigerant passing through the second flow path, the bubbles generated in the heat receiver are condensed, A gas-liquid separator comprising a first preheating unit for preheating the refrigerant cooled by the radiator;
A second preheating unit that is in thermal contact with the heat receiver and further preheats the refrigerant preheated in the first preheating unit;
A bubble pump type cooling device.   The bubble pump type cooling device according to claim 1, wherein the second preheating unit is provided in the heat receiver. The heat receiver includes an upper wall connecting the first flow path and the second flow path, a bottom wall, a side wall having the heat receiving surface connecting the upper wall and the bottom wall, and an internal space of the heat receiver. A partition wall extending in the direction of gravity that divides the heat receiving space communicated with the first flow path and the preheating space communicated with the second flow path;
The bubble pump type cooling according to claim 2, wherein a gap is provided between the lower end in the gravitational direction of the partition wall and the bottom wall to communicate the preheating space and the heat receiving space, and the preheating space functions as the second preheating portion. apparatus.   4. The bubble pump type cooling device according to claim 3, wherein a plurality of rectifying plates extending vertically in the direction of gravity are provided on at least one surface of the partition wall. The heat receiver includes an upper wall connected to the first flow path, a bottom wall, a first side wall having the heat receiving surface connecting the upper wall and the bottom wall, and an internal space of the heat receiver as the first wall. A heat receiving space in which the flow path communicates,
The second flow path extends along the heat receiver, and at least one second flow path outlet is provided on the second side wall facing the first side wall, and a part of the second flow path is The bubble pump type cooling device according to claim 1, which functions as a second preheating unit.   2. The first preheating part is in contact with a peripheral wall of the first flow path, and a part of the second flow path is in contact with the first flow path along the axis of the first flow path. The bubble pump type cooling device described in 1.   2. The bubble pump type cooling device according to claim 1, wherein the gas-liquid separator has a double pipe structure in which the first flow path is an inner side and the second flow path is an outer side. The bubble pump type cooling device according to claim 1, further comprising a fan that sends air to a heat radiating plate of the radiator.

Images