Boiling enhancer and vapor chamber

Abstract

The present invention provides a boiling enhancer and a vapor chamber that are capable of improving a boiling enhancement effect.　The boiling enhancer (1) comprises a base part (2) and a plurality of fins (3) erected from the base part (2). The fins (3) each have a body part (32) that extends perpendicularly to the base part (2) and an inclined part (31) that is inclined with respect to the body part (32) at a connecting portion with the base part (2), and the entire surface thereof is textured.

Description

Boiling acceleration section and vapor chamber

[0001] This invention relates to a boiling acceleration unit and a vapor chamber.

[0002] Conventionally, a boiling transfer surface for a boiling cooler has been proposed in which the tip of a fin is bent and joined to an adjacent fin, and a small hole is formed at the top (see, for example, Patent Document 1). In the boiling transfer surface described in Patent Document 1, a cavity is formed between adjacent fins, making it easier for bubble nuclei to be generated within the cavity.

[0003] Japanese Patent Publication No. 2014-75563

[0004] In structures that promote boiling by forming cavities, the heat transfer coefficient can be increased by increasing the density of the cavities. However, in structures like the one described in Patent Document 1, the upper limit of the number of cavities is determined by the number of fins, making it difficult to achieve a density above a certain level, and further improvement of the boiling promotion effect was desired.

[0005] The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a boiling acceleration unit and a vapor chamber that can improve the boiling acceleration effect.

[0006] To achieve the above objective, the boiling promotion unit according to the present invention comprises a base portion and a plurality of fins erected from the base portion, wherein the entire surface of the fins is a pear-skin texture.

[0007] A boiling-promoting unit according to one aspect of the present invention has a fin comprising a main body portion extending perpendicularly to the base portion and an inclined portion that is inclined relative to the main body portion at the connection portion with the base portion.

[0008] In one aspect of the present invention, the boiling-promoting unit has a base that is formed in a plate shape and has a thickness of 0.5 mm or more.

[0009] A boiling-promoting unit according to one aspect of the present invention has a base portion comprising a fin arrangement region on which the fins are provided, and an edge portion formed around the fin arrangement region.

[0010] In one embodiment of the present invention, the boiling-promoting unit has a surface roughness Ra of 0.5 μm or more on the pear-skin surface of the fins.

[0011] In one aspect of the present invention, the boiling-promoting section is configured such that a plurality of fins are arranged in the direction of the plate thickness to form a fin group, and the plurality of fin groups are arranged in the direction in which the fins extend along the base portion.

[0012] In one aspect of the present invention, the boiling-promoting section has the base section and the plurality of fins formed integrally.

[0013] In one aspect of the present invention, the boiling-promoting section has a plurality of fins whose height decreases as they move toward one side in the direction extending along the base section.

[0014] In one aspect of the present invention, the boiling-promoting section has a plurality of fins with heights of 0.5 mm or more and 20 mm or less.

[0015] In one aspect of the present invention, the boiling-promoting section has a thickness of 1 mm or less for the plurality of fins.

[0016] To achieve the above objective, the vapor chamber according to the present invention comprises a vapor chamber body thermally connected to a heat source and the boiling promotion unit described above, and is provided with a soldering portion connecting the vapor chamber body and the boiling promotion unit.

[0017] To achieve the above objective, the vapor chamber according to the present invention comprises a vapor chamber body thermally connected to a heat source and a boiling acceleration unit as described in claim 1, wherein a welded portion is provided connecting the vapor chamber body and the boiling acceleration unit.

[0018] The boiling acceleration unit and vapor chamber according to the present invention can improve the boiling acceleration effect.

[0019] This is a schematic side view showing a cooling system equipped with a boiling-promoting unit according to the first embodiment of the present invention. This is a perspective view showing the boiling-promoting unit according to the first embodiment of the present invention. This is a cross-sectional view showing the boiling-promoting unit according to the first embodiment of the present invention. This is a perspective view showing the boiling-promoting unit according to the second embodiment of the present invention. This is a perspective view showing the boiling-promoting unit according to embodiments and modifications of the present invention. This is a graph showing the relationship between the heat flux and heat transfer coefficient of the boiling-promoting unit according to embodiments and modifications of the present invention. Heat flux of the boiling-promoting unit according to embodiments and modifications of the present invention: 25 W / cm ２ This is a graph showing the heat transfer coefficient at a given time. This is a graph showing the heat transfer coefficient at the critical heat flux point or heat transfer coefficient reduction point of the boiling acceleration section according to the embodiment and modification of the present invention. Heat flux of 48 W / cm for the boiling acceleration section according to the embodiment and modification of the present invention ２ This is a graph showing the heat transfer coefficient at a given time.

[0020] [First Embodiment] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. Figure 1 is a schematic side view showing a cooling system 220 provided with a boiling promotion unit 1 according to the first embodiment of the present invention, Figure 2 is a perspective view showing the boiling promotion unit 1, and Figure 3 is a cross-sectional view showing the boiling promotion unit 1.

[0021] As shown in Figures 1 to 3, the boiling accelerating unit 1 according to the first embodiment of the present invention comprises a base portion 2 and a plurality of fins 3 erected from the base portion 2. Each fin 3 has a main body portion 32 extending perpendicularly to the base portion 2 and an inclined portion 31 that is inclined relative to the main body portion 32 at the connection portion with the base portion 2, and its entire surface is pear-skin shaped.

[0022] The vapor chamber 10 comprises a vapor chamber body 11 that is thermally connected to a heat source 100, and a boiling accelerator 1. The vapor chamber body 11 and the boiling accelerator 1 are connected by a connecting portion 12, which is a soldered portion formed by soldering, or a welded portion formed by welding (preferably laser welding).

[0023] The vapor chamber 10 can be used in a cooling system 220, for example, as shown in Figure 1. The cooling system 220 comprises a cooling device 210 and a secondary refrigerant cooling section 221 to which a condensing pipe 204 extending from the cooling device 210 is connected, and a liquid-phase secondary refrigerant 202 flowing through the condensing pipe 204 circulates between the cooling device 210 and the secondary refrigerant cooling section 221. The cooling device 210 has a liquid-phase primary refrigerant 201 sealed and stored inside a container 200, and a condensing pipe 204 through which the liquid-phase secondary refrigerant 202 flows, penetrating a gas phase section 203 inside the container 200, and a heat source 100 is immersed in the liquid-phase primary refrigerant 201 sealed inside the container 200. When the vapor chamber 10 is immersed in the liquid-phase primary refrigerant 201, it is thermally connected to the heat source 100 which is immersed in the liquid-phase primary refrigerant 201.

[0024] The vapor chamber body 11 comprises a container with a cavity formed inside, a working fluid sealed in the cavity, and a vapor passage provided in the cavity through which the gaseous working fluid flows. The container is a thin, plate-shaped container.

[0025] The vapor chamber body 11 has a plate portion 111 extending along a predetermined plane and a protrusion 112 projecting from one surface of the plate portion, with a boiling accelerator 1 provided on the other surface of the plate portion 111. The vapor chamber body 11 is thermally connected to the heat source 100 by the protrusion 112 contacting the heat source 100. The internal space of the plate portion 111 and the internal space of the protrusion 112 are in communication with each other, forming a cavity in the container. The vapor chamber 10, equipped with such a vapor chamber body 11 and boiling accelerator 1, is a flat-type heat pipe.

[0026] The boiling-promoting section 1 integrally comprises a base section 2 and a plurality of fins 3. The boiling-promoting section 1 is formed from a metal such as copper or a copper alloy, and the base section 2 and the fins 3, which are skived fins, are integrally formed by skiving the metal block.

[0027] As shown in Figure 2, the base portion 2 is formed in the shape of a rectangular plate, with fins 3 provided on one surface 2A, and the other surface 2B serving as a connecting surface for connection to the plate portion 111 of the vapor chamber body 11. The above-mentioned connecting portion 12 is provided between the other surface 2B and the plate portion 111. From the viewpoint of workability when skiving, the thickness (plate thickness) of the base portion 2 is preferably 0.5 mm or more.

[0028] The fin 3 is formed in a plate shape that is erected from the base portion 2 and has a main body portion 32 and an inclined portion 31. The main body portion 32 extends perpendicularly or substantially perpendicularly to the plate-shaped base portion. The inclined portion 31 is provided at the connection point between the base portion 2 and the fin 3 and is inclined with respect to the main body portion 32. That is, the inclined portion 31 is inclined with respect to a direction perpendicular to the base portion 2. Thus, the fin 3 has a shape that protrudes from the base portion 2 inclined with respect to a vertical direction and then extends along that vertical direction. The inclination angle of the inclined portion 31 with respect to the main body portion 32 (the inclination angle with respect to a direction perpendicular to the base portion 2) is preferably, for example, 40 to 50°.

[0029] In the following explanation, for the sake of clarity, the direction along the base portion 2 of the plate-shaped fin 3 will be referred to as the extension direction of the fin 3, and the direction perpendicular to the base portion 2 will be referred to as the protrusion direction of the fin 3. Furthermore, the direction in which multiple fins 3 are aligned will be referred to as the parallel direction.

[0030] As a result of the inclined portion 31 described above, a triangular cross-sectional opposing space S1 is formed in the boiling promotion portion 1 on the acute-angle side between the base portion 2 and the inclined portion 31. The opposing space S1 is a region enclosed by one surface 2A of the base portion 2, the acute-angle side surface of the inclined portion 31, and a line that virtually extends the main body portion 32 toward the surface 2A.

[0031] The surface of the fin 3 is subjected to embossing, and the entire surface of the fin 3 is an embossed surface. As a method of performing embossing, for example, wet etching is preferable, but sandblasting, sintering of metal powder (copper powder), or the like may also be used. The surface roughness Ra of the embossed surface can be appropriately selected according to the usage conditions of the boiling promotion part 1 and the physical properties of the liquid-phase refrigerant in which the heat source 100 is immersed. From the viewpoint of making the unevenness on the embossed surface into fine cavities and facilitating the formation of boiling nuclei as described later, the surface roughness (arithmetic mean roughness) Ra of the embossed surface is preferably 0.5 μm or more.

[0032] Further, the surface roughness (maximum height roughness) Rz of the embossed surface can be appropriately selected according to the usage conditions of the boiling promotion part 1 and the physical properties of the liquid-phase refrigerant in which the heat source 100 is immersed. From the viewpoint of making the unevenness on the embossed surface into fine cavities and facilitating the formation of boiling nuclei as described later, the surface roughness Rz of the embossed surface is preferably 3 to 8 μm.

[0033] Among the fins 3, in particular, the main body portion 32 extends along the long side direction of the rectangular base portion 2, and a plurality of fins 3 are arranged side by side in the short side direction of the base portion 2. That is, among the fins 3, in particular, the main body portion 32 extends along a plane including both the long side direction of the base portion 2 and the direction perpendicular to the base portion 2.

[0034] The base portion 2 has, on one surface 2A thereof, a fin arrangement region 2C where the fins 3 are provided and an edge portion 2D formed around the fin arrangement region 2C. The fin arrangement region 2C is formed in a rectangular shape. The edge portion 2D is a region where the fins 3 are not provided and is formed in a rectangular frame shape so as to surround the fin arrangement region 2C.

[0035] The vapor chamber 10 is provided in the cooling system 220 in such a direction that the plate portion 111 of the vapor chamber main body 11 and the base portion 2 of the boiling promotion part 1 extend along the vertical direction. At this time, the rectangular plate portion 111 and the base portion 2 are oriented such that their long side directions are along the vertical direction. Thereby, a plurality of fins 3 are arranged along one direction in the horizontal plane, and the fins 3 extend along the vertical direction.

[0036] Here, the boiling and evaporation modes of the liquid-phase primary refrigerant 201 in the boiling promotion section 1 will be described. First, the heat generated from the heat source 100 is transmitted to the boiling promotion section 1 through the vapor chamber main body 11. In the boiling promotion section 1, heat conduction occurs from the base portion 2 to each of the plurality of fins 3, and heat is mainly transferred from the surface of the fin 3 to the primary refrigerant 201, causing evaporation.

[0037] At this time, first, due to the formation of the opposing space S1 by the inclined portion 31 as described above, the opposing space S1 becomes a cavity, which contributes to the promotion of boiling and can achieve high heat transfer. In particular, when the calorific value of the heat source 100 is large, it is easy to contribute to the promotion of boiling at high heat fluxes.

[0038] At positions of the fin 3 that are far from the base portion 2 (for example, positions more than 1 mm away), although the degree of superheat is lower compared to the opposing space S1 and its vicinity, due to the surface of the fin 3 being a dimpled surface, the unevenness on the dimpled surface serves as fine cavities, promoting boiling.

[0039] As described above, the primary refrigerant 201 that has boiled and evaporated becomes a gas and its density decreases, so it tends to flow upward in the vertical direction. Since the fins 3 extend along the vertical direction, the gaseous primary refrigerant 201 passes between adjacent fins 3 and is discharged upward along the fins 3 in the vertical direction. By discharging the primary refrigerant 201 in this way, a fluid flow upward in the vertical direction is generated, and newly liquid-phase primary refrigerant 201 is supplied between adjacent fins 3. Therefore, even at high heat fluxes, it is easy to maintain the surface of the fin 3 in a wetted state, suppressing burnout and maintaining nucleate boiling.

[0040] Next, the details of the dimensions of each part of the fin 3 will be described. As shown in FIGS. 2 and 3, let the height (dimension in the protruding direction) of the fin 3 be H, the thickness (dimension in the parallel direction) of the fin 3 be T, and the gap (interval in the parallel direction) between adjacent fins 3 be G.

[0041] The height H of the fins 3 can be appropriately selected depending on the operating conditions of the boiling accelerator 1 and the physical properties of the refrigerant in the liquid phase into which the heat source 100 is immersed. As described above, in order to maintain the surface of the fins 3 in a wet state, the height H of the fins 3 is preferably 0.5 mm or more, more preferably 1 mm or more, and even more preferably 2 mm or more. Also, in order to reduce the portion of the fins 3 that is far from the base portion 2 and has a low degree of superheating, the height H of the fins 3 is preferably 15 mm or less, and more preferably 8 mm or less. In this embodiment, the vapor chamber 10 is composed of a vapor chamber body 11 in which a working fluid is sealed in a cavity and thermally connected to the heat source 100, and a boiling accelerator 1. However, the vapor chamber may be composed without a vapor chamber body by having the heat source in direct contact with the boiling accelerator. In such a configuration, in order to secure a heat transfer area and to increase the heat flux at the CHF point, which will be described later, the height H of the fins may be made relatively high, for example, 20 mm or less. Furthermore, the height H of multiple fins 3 is the same, and the height H of the fins 3 does not change with respect to their position in the extension direction; it remains constant.

[0042] The gap G can be appropriately selected depending on the operating conditions of the boiling acceleration unit 1 and the physical properties of the refrigerant in the liquid phase into which the heat source 100 is immersed. The gap G is preferably 0.06 mm or more, and more preferably 0.08 mm or more, from the standpoint of improving the heat transfer coefficient by utilizing the unevenness of the pear-shaped surface as a cavity, and from the standpoint of facilitating passage when the evaporation rate of the primary refrigerant 201 increases. Furthermore, the gap G is preferably 1 mm or less from the standpoint of ensuring the density of the opposing space S1 as a cavity and improving the heat transfer coefficient.

[0043] The thickness T can be appropriately selected depending on the operating conditions of the boiling accelerator 1 and the physical properties of the refrigerant in the liquid phase into which the heat source 100 is immersed. From the viewpoint of processability when cutting and raising the fins 3 by skiving, the thickness T is preferably 0.06 mm or more, and more preferably 0.08 mm or more. Furthermore, from the viewpoint of ensuring the density of the fins 3 and improving the heat transfer coefficient, the thickness T is preferably 1 mm or less.

[0044] According to the boiling-promoting unit 1 of the first embodiment of the present invention described above, the boiling-promoting effect can be improved because the fin 3 has an inclined portion 31 and the entire surface of the fin 3 is a textured surface. That is, although there is an upper limit to the number of cavities formed by the inclined portion 31, cavities can also be formed by the textured surface, and compared to a configuration in which cavities are formed only by the shape of the fins, it is easier to form boiling nuclei and improve the boiling-promoting effect.

[0045] Furthermore, even if the density of the fine cavities formed by the pear-shaped surface is increased, the spaces are partitioned by fin 3, preventing bubbles from merging within these partitioned spaces. This suppresses burnout caused by bubbles becoming larger.

[0046] Furthermore, the base portion 2 having an edge portion 2D in addition to the fin arrangement region 2C improves machinability when skiving and also improves workability when attaching to other parts (for example, vapor chambers or heat sources).

[0047] Furthermore, since the base portion 2 and the multiple fins 3 are integrally formed, the number of parts can be reduced, and heat can be easily transferred between the base portion 2 and the fins 3.

[0048] Furthermore, since the boiling acceleration unit 1 is connected to the vapor chamber body 11 by a connecting part 12 which is a soldering or welding part, the boiling acceleration unit 1 can be molded independently of the vapor chamber body 11 and then joined to the vapor chamber body 11, thereby improving processability.

[0049] [Second Embodiment] A second embodiment of the present invention will be described with reference to the drawings. Figure 4 is a perspective view showing the boiling promotion unit 4 according to the second embodiment of the present invention. In the following, components having the same shape or function as those in the first embodiment will be denoted by the same reference numerals as in the first embodiment and their descriptions will be omitted. The differences from the first embodiment will be described in detail.

[0050] The boiling-promoting section 4 according to the second embodiment has a base section 2 and a plurality of fins 5. The fins 5 have a main body section and an inclined section, similar to the first embodiment, and their entire surface is a pear-skin texture. The plurality of fins 5 form first to third fin groups 51 to 53. In each of the first to third fin groups 51 to 53, the plurality of fins 5 are arranged in the direction of their plate thickness. The first to third fin groups 51 to 53 are arranged in this order in a predetermined direction, and this direction of arrangement coincides with the extension direction (vertical direction) of each fin 5.

[0051] In other words, the fin 3 of the first embodiment is divided into three parts in its extending direction, which corresponds to the fin 5 of the second embodiment 5. The number of divisions (number of fin groups) is not particularly limited and may be two, four or more.

[0052] According to the boiling-promoting unit 4 of the second embodiment of the present invention described above, similar to the boiling-promoting unit 1 of the first embodiment, the fin 5 has a main body portion and an inclined portion, similar to the first embodiment, and its entire surface is pear-skinned, thereby improving the boiling-promoting effect.

[0053] Furthermore, since the multiple fin groups 51 to 53 are aligned in the direction of extension of the fin 5, the primary refrigerant 201 in the gas phase can be discharged between the fin groups 51 to 53. This ensures discharge even when the fins 5 are provided on the base portion 2 over a wide area in the direction of extension, or when the height of the fins 5 is high, and facilitates the generation of fluid flow toward the upward in the vertical direction.

[0054] Although embodiments of the present invention have been described above, the present invention is not limited to the boiling-promoting unit according to the above embodiments, but includes all embodiments that fall within the concept and scope of the present invention. Furthermore, each component may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. For example, the shape, material, arrangement, size, etc., of each component in the above embodiments may be appropriately changed depending on the specific use of the present invention.

[0055] For example, in the above embodiment, the height H of the fin 3 was assumed to be constant and not change with respect to its position in the extending direction. However, the fin may have a slope such that the height H of the fin decreases as it moves toward one side in the extending direction of the fin. In this case, the boiling promotion section is provided in the cooling system in such a orientation that the height H of the fin decreases as it moves toward the upward side in the vertical direction. With such a configuration, even when the extension dimension of the fin is large, the discharge of the primary refrigerant can be ensured, and it is easy to generate a fluid flow toward the upward side in the vertical direction.

[0056] [Examples] Examples and comparative examples of the present invention will now be described. The boiling acceleration unit 6 in Examples 1 to 7 and Comparative Examples 1 to 7 has a base portion 2 and a plurality of fins 7, as shown in Figure 5, and the height H, thickness T, and gap G of the fins 7 are different in each of Examples 1 to 7 and Comparative Examples 1 to 7. The boiling acceleration unit 6 was oriented so that the base portion 2 extends along the vertical direction, similar to the first and second embodiments, and the heat transfer coefficient with respect to the heat flux was measured by heating the other side 2B of the base portion 2 (vapor chamber body 11 side) with a heater.

[0057] Table 1 shows the height H, thickness T, and gap G for Examples 1 to 7. In Examples 1 to 7, the entire surface of the fin 7 is textured, while in Comparative Examples 1 to 7, the surface of the fin 7 is not textured. The dimensions of the fin 7 in Comparative Examples 1 to 7 are the same as the dimensions of the fin 7 in Examples 1 to 7. That is, if the dimensions of the fin 7 in Examples 1 to 7 are conditions A to F, then Comparative Examples 1 to 7 correspond to conditions A to F, respectively. Comparative Example 8 is a boiling accelerator that uses three metal meshes with a mesh count of #350 pressed together instead of fins 7. Furthermore, Example 8 is a fin 7 with a height H of 5 mm, a thickness T of 0.1 mm, and a gap G of 0.1 mm, where the entire surface of the fin 7 is textured, while Comparative Example 9 is a fin 7 with the same dimensions but without a textured surface. Furthermore, Example 9 is defined as a fin 7 with a height H of 10 mm, a thickness T of 0.1 mm, and a gap G of 0.1 mm, where the entire surface of the fin 7 is textured, while Comparative Example 10 is defined as a fin 7 with the same dimensions but without textured surface treatment.

[0058]

[0059] Figure 6 shows the measurement results of the heat transfer coefficient with respect to heat flux for Examples 1 to 7 and Comparative Examples 1 to 8. Furthermore, for Examples 2, 3, 7 and Comparative Examples 1 to 8, the heat flux was 25 W / cm². ２ The heat transfer coefficient (kW / m) in this case ２ K) is shown in Figure 7, and the heat transfer coefficient at the critical heat flux point (CHF) or the heat flux at which the heat transfer coefficient begins to decrease (heat transfer coefficient decrease point) is (kW / m ２ K) is shown in Figure 8, with a heat flux of 48 W / cm². ２ The heat transfer coefficient (kW / m) in this case ２ Figure 9 shows K). Detailed numerical values ​​for Figures 7-9 are shown in Tables 2-4. The improvement rates in Tables 2-4 are based on Comparative Example 8.

[0060]

[0061]

[0062]

[0063] [Comparison when the heat flux is 25 W / cm ２ : In Examples 1 to 7, an improvement in the heat transfer coefficient was confirmed with respect to Comparative Example 8. In Comparative Examples 1 to 7, except for Comparative Example 2, the heat transfer coefficient did not improve with respect to Comparative Example 8. Also, the improvement rates of Examples 1 to 7 with respect to Comparative Example 8 were higher than the improvement rates of Comparative Examples 1 to 7 with respect to Comparative Example 8, respectively. That is, when the heat flux is 25 W / cm ２ , simply changing the boiling promotion part from a mesh to fins hardly improved the heat transfer coefficient, but an improvement in the heat transfer coefficient was observed by making the surface of the fins into a dimpled surface after changing to fins.

[0064] [Regarding the heat transfer coefficient drop point]: In Examples 2, 3, 7 and Comparative Examples 1 to 7, the heat transfer coefficient drop point increased with respect to Comparative Example 8. That is, an increase in the heat transfer coefficient drop point was observed by changing the boiling promotion part from a mesh to fins. Furthermore, in Examples 2, 3, 7, an improvement in the heat transfer coefficient was confirmed with respect to Comparative Example 8. In Comparative Examples 1 to 7, there were conditions where the heat transfer coefficient improved and conditions where it did not improve with respect to Comparative Example 8. Also, the improvement rates of Examples 2, 3, 7 with respect to Comparative Example 8 were higher than the improvement rates of Comparative Examples 1 to 7 with respect to Comparative Example 8. That is, at the heat transfer coefficient drop point, simply changing the boiling promotion part from a mesh to fins hardly improved the heat transfer coefficient, but an improvement in the heat transfer coefficient was observed by making the surface of the fins into a dimpled surface after changing to fins.

[0065] [Comparison when the heat flux is 48 W / cm ２ : In Comparative Example 8, burnout occurred, whereas in Examples 1 to 7 and Comparative Examples 1 to 7, burnout did not occur. The heat transfer coefficients of Examples 3, 4, 7 were higher than all the heat transfer coefficients of Comparative Examples 1 to 7.

[0066] [Comparison with or without a dimpled surface]: In the heat flux range below the CHF or the heat transfer coefficient drop point, as shown in Tables 2 and 3, for all of Examples 1 to 7 where the entire surface of the fin 7 is a dimpled surface, an improvement in the heat transfer coefficient was observed with respect to each of Comparative Examples 1 to 7 of the same dimensions without dimpling treatment. Thus, by making the entire fin 7 into a dimpled surface, an improvement in the heat transfer coefficient was confirmed in the heat flux range below the CHF or the heat transfer coefficient drop point. Also, at 48 W / cm ２In terms of heat flux, Examples 3 to 7, where the entire surface of the fin 7 is textured, showed an improvement in heat transfer coefficient compared to Comparative Examples 3 to 7, which were the same dimensions but without textured processing. Specifically, under the conditions of a thickness T of 0.1 mm or more and a gap G of 0.1 mm, an improvement in heat transfer coefficient was confirmed even in a relatively high heat flux range. Furthermore, under the condition of a height of 5 mm or more, if the dimensional conditions were the same, an improvement in heat transfer coefficient was confirmed by textured processing, as shown in Figure 6. Specifically, Example 8 had a higher heat transfer coefficient than Comparative Example 9, and Example 9 had a higher heat transfer coefficient than Comparative Example 10.

[0067] [Comparison of fins and mesh] In Comparative Example 8, which used a metal mesh, the heat flux was 28 W / cm². ２ A sharp decrease in heat transfer coefficient was observed at this point. In contrast, in Examples 1-7 and Comparative Examples 1-7, which used fins, the point at which the heat transfer coefficient decreased was 30 W / cm². ２ Furthermore, the rate of decrease in heat transfer coefficient was extremely low. In Comparative Example 8, the heat flux was 28 W / cm². ２ In contrast to the above, burnout occurred in all measurement ranges in Examples 1-7 and Comparative Examples 1-7.

[0068] [Regarding the fin gap] The only difference between Example 3 and Example 7 is the size of the gap G. Heat flux: 45 W / cm ２ In the following, the heat transfer coefficient of Example 3, where the gap G is small, is high, and at higher heat fluxes, the heat transfer coefficient reverses, with the heat transfer coefficient of Example 7, where the gap G is large, being relatively high. Similarly, in Comparative Example 3 and Comparative Example 7, only the size of the gap G differs, and a similar trend was observed.

[0069] [Regarding fin thickness] The only difference between Example 6 and Example 7 is the thickness T. In the entire heat flux range, the heat transfer coefficient was higher in Example 7, where the thickness T was smaller.

[0070] [Regarding fin thickness and gap] In Examples 1 to 6, the ratio of thickness T to gap G is 1:1. The heat flux is 48 W / cm². ２In the following examples, the heat transfer coefficient was highest in Example 3, where the thickness T and gap G were 0.1 mm. As the thickness T and gap G decreased, the heat transfer coefficient decreased, and as the thickness T and gap G increased, the heat transfer coefficient increased. Also, the heat flux was 48 W / cm². ２ When the value increased above this, the difference in heat transfer coefficients between Examples 3 to 6 decreased. That is, when the heat flux was 48 W / cm², the difference in heat transfer coefficients between Examples 3 and 6 decreased. ２ In the range greater than this, as the thickness T and gap G increased, the heat transfer coefficient tended to decrease less even when the heat flux increased.

[0071] 1, 4, 6... Boiling acceleration section, 2... Base section, 3, 5, 6... Fins, 31... Inclined section, 32... Main body section, 2C... Fin arrangement area, 2D... Edge section, 51-53... Fin group, 10... Vapor chamber, 11... Vapor chamber body, 12... Connection section (soldering section, welding section)

Claims

1. A boiling-promoting section comprising a base portion and a plurality of fins erected from the base portion, wherein the entire surface of the fins is a pear-skin textured surface.

2. The boiling accelerating part according to claim 1, wherein the fin has a main body portion extending perpendicularly to the base portion and an inclined portion that is inclined with respect to the main body portion at the connection portion with the base portion.

3. The boiling accelerating part according to claim 1 or 2, wherein the base portion is formed in a plate shape and has a thickness of 0.5 mm or more.

4. The boiling accelerating unit according to claim 1 or 2, wherein the base portion comprises a fin arrangement region on which the fins are provided and an edge portion formed around the fin arrangement region.

5. The boiling accelerating unit according to claim 1 or 2, wherein the surface roughness Ra of the pear-shaped surface of the fin is 0.5 μm or more.

6. The boiling accelerating part according to claim 1 or 2, wherein the fins are arranged in a plurality in the direction of their plate thickness to form a fin group, and the plurality of fin groups are arranged in the direction in which the fins extend along the base portion.

7. The boiling accelerating unit according to claim 1 or 2, wherein the base portion and the plurality of fins are integrally formed.

8. The boiling accelerating unit according to claim 1 or 2, wherein the height of the plurality of fins decreases toward one side in the direction extending along the base portion.

9. The boiling accelerating unit according to claim 1 or 2, wherein the height of the plurality of fins is 0.5 mm or more and 20 mm or less.

10. The boiling accelerating unit according to claim 1 or 2, wherein the thickness of the plurality of fins is 1 mm or less.

11. A vapor chamber comprising a vapor chamber body thermally connected to a heat source and a boiling accelerator as described in claim 1, wherein a soldering portion is provided for connecting the vapor chamber body and the boiling accelerator.

12. A vapor chamber comprising a vapor chamber body thermally connected to a heat source and a boiling accelerator as described in claim 1, wherein a welded portion is provided connecting the vapor chamber body and the boiling accelerator.

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