An enhanced heat dissipation device using an array of heat dissipation fins

Abstract

The present invention discloses a heat dissipation enhancement device using an array of heat dissipation fins, which relates to the technical field of heat dissipation of electronic components. The fin substrate and the cover plate of the heat dissipation device enclose a hollow cavity with both ends open. One end of the hollow cavity is connected to a cooling medium supply device, and the other end of the hollow cavity is connected to a cooling medium recovery device; the heat dissipation fins are trapezoidal or triangular, and the heat dissipation fins are located at the top of the fin substrate and distributed in the hollow cavity; the heat dissipation fins perpendicular to the flow direction of the cooling medium are evenly distributed at equal intervals, and the heat dissipation fins parallel to the flow direction of the cooling medium are evenly distributed at equal intervals and adjacent heat dissipation fins are centrosymmetric. There are main channels and secondary channels in the heat dissipation fins. The secondary channels form two complementary angles with the flow direction of the cooling medium, so that the secondary flow periodically detaches from the main flow and then merges into the main flow, having a relatively high convective heat transfer coefficient, and the temperature distribution of the heat source is uniform; the cross-sectional area of the flow passage is increased, the flow velocity of the main flow is reduced, and the pressure drop is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation of electronic components, and particularly to a heat dissipation enhancement device using an array of heat dissipation fins. Background Art

[0002] Methods for enhancing convective heat transfer mainly include: increasing the heat transfer area, increasing the flow velocity, introducing phase change, increasing disturbance to generate secondary flow, improving the thermophysical properties of the fluid, etc. In heat transfer applications such as heat dissipation of electronic components, due to the large heat flux density, heat sinks generally need to be provided with fins to increase the heat transfer area.

[0003] There are many types of fin structures for enhancing heat transfer. Common ones include plain fins, corrugated fins, pin fins, radiating fins, etc. The fin body of a plain fin is a slender strip, which can increase the heat transfer area in the direction perpendicular to the heat source. It has the advantages of simple structure and easy processing, and is also the most widely used. The methods to improve the heat dissipation capacity of plain fins are to increase the fin height and reduce the fin thickness. However, these two shape changes will cause a decrease in fin efficiency, a decrease in the heat dissipation capacity per unit heat transfer area, and also introduce more pressure drops. In addition, when the fluid travels along the plain fin, both the velocity boundary layer and the thermal boundary layer will gradually thicken, resulting in the attenuation of heat transfer performance along the flow direction. The corrugated fin also has the above problems.

[0004] As described in the patent CN110198615B, a radiating fin is a structure that uses plain fins to form a gradually expanding flow channel and increases the number of fins in the flow direction. This design can break the gradually increasing boundary layer on the fin surface through the increased number of fins, thereby improving the heat dissipation performance. However, the problem is that the shape of the fin substrate is irregular, making it difficult to utilize the entire effective heat dissipation area. In addition, the closer the channel is to the inlet, the sparser the fins become exponentially, resulting in a significant reduction in heat dissipation capacity and forming hot spots; the closer to the outlet, the denser the fins become exponentially, introducing an excessive pressure drop.

[0005] Patent CN103503591B describes a needle-shaped fin array structure. The fin body is cylindrical, and special-shaped flow guiding structures are respectively arranged on the windward / leeward sides of the cylinder. The needle-shaped fins in adjacent rows are staggered to increase disturbance. Such needle-shaped fins also include shapes such as square (US6273186B1), circular (US6173758B1), elliptical (US20090145581A1), etc. Most of these needle-shaped fin array designs use the staggered arrangement method to enhance disturbance and strengthen heat dissipation. Such a design introduces too many bends in the flow field and doubles the actual length of the working fluid flow, so the pressure drop is relatively high. The diamond-shaped fin array used in CN102713490A adopts the in-line arrangement method. However, the problem is that the secondary flow in the sub-channel will converge the flow to one side of the heat dissipation device, resulting in poor heat transfer capacity on the other side. And due to the increased flow velocity caused by the convergence and the pressure loss caused by the secondary flow, the pressure drop of the system will increase, and the total pressure drop is even higher than that of the flat fins. Summary of the Invention

[0006] The purpose of the present invention is to provide a heat dissipation enhancing device using an array of heat dissipation fins, which solves the problems of large pressure drop in the existing fin structure and poor heat transfer capacity caused by the convergence of secondary flow.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions: A heat dissipation enhancing device using an array of heat dissipation fins, characterized in that: it includes a fin substrate, heat dissipation fins and a cover plate. The fin substrate and the cover plate enclose a hollow cavity with both ends open. One end of the hollow cavity is connected to a cooling medium supply device, and the other end of the hollow cavity is connected to a cooling medium recovery device; the heat dissipation fins are trapezoidal or triangular, and the heat dissipation fins are located at the top of the fin substrate and are distributed in the hollow cavity; the heat dissipation fins perpendicular to the cooling medium flow direction are evenly distributed at equal intervals, and the heat dissipation fins parallel to the cooling medium flow direction are evenly distributed at equal intervals and adjacent heat dissipation fins are centrosymmetric.

[0008] A further technical solution is that when the heat dissipation fin is a trapezoidal fin, the trapezoid is an isosceles trapezoid, the length of the long side is 1 - 3.5 mm, the length of the short side is 0.1 - 0.7 mm, and the thickness is 0.1 - 0.6 mm; a sub-channel is formed between adjacent and parallel hypotenuses, and the sub-channel spacing is 0.1 - 0.4 mm. A main channel is formed between adjacent long sides and short sides, and the main channel spacing is 0.2 - 0.6 mm.

[0009] A further technical solution is that when the heat dissipation fin is a triangular fin, the trapezoid is an isosceles triangle, the length of the base is 1 - 3.5 mm, and the length of the waist is 0.6 - 1.8 mm; a sub-channel is formed between adjacent and parallel hypotenuses, and the sub-channel spacing is 0.1 - 0.4 mm. A main channel is formed between adjacent bases, and the main channel spacing is 0.1 - 0.6 mm.

[0010] A further technical solution is that the inner side wall of the cover plate is inclined, and the gap between the inner side wall of the cover plate and the top of the heat dissipation fins gradually decreases along the fluid direction.

[0011] A further technical solution is that the inner side wall of the cover plate bulges downward to form a convex part.

[0012] Working principle: The bottom surface of the fin substrate is in contact with the surface of the electronic component serving as the heat source. The cooling medium flows through the channels formed by the fins in the heat dissipation device, taking away the heat on the fin substrate and the heat dissipation fins, so as to achieve the purpose of dissipating heat from the electronic component. In the array distribution of the heat dissipation fins, the cooling medium in the main channel serves as the main flow, and the cooling medium in the secondary channel serves as the secondary flow. Since the secondary channel forms two complementary angles with the flow direction of the cooling medium, the secondary flow periodically detaches from the main flow and then merges into the main flow, making the flow channel have a larger effective cross-sectional area for flow, a smaller pressure drop, and a uniform temperature distribution of the heat source. At the same time, since the gap between the cover plate and the top of the fins is relatively large in the upstream part of the heat dissipation fins, part of the working medium does not contact the heat dissipation fin array and directly flows away from above the heat dissipation fins, thereby further reducing the pressure drop. In the downstream part of the heat dissipation fins, since the gap between the cover plate and the top of the fins becomes smaller, all the fluid enters the heat dissipation fin array, thus ensuring the heat exchange effect downstream. Inside the heat dissipation fin array, since the temperature and flow rate of the working medium are both lower in the upstream and higher in the downstream, the temperature distribution of the heat source is uniform.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: Provide a reinforced heat dissipation device using array heat dissipation fins with a simple structure. By arranging trapezoidal or triangular fins in an array that is uniform and centrosymmetric along the flow direction of the cooling medium, a main channel and a secondary channel exist in the heat dissipation fins. The secondary channel forms two complementary angles with the flow direction of the cooling medium, enabling the wall surface in the secondary channel to also participate in convective heat transfer, thereby increasing the heat transfer area. At the same time, the secondary flow periodically detaches from the main flow and then merges into the main flow, causing the boundary layer of the main flow to be periodically broken and rebuilt, so that the flow is always in the developing region, having a relatively high convective heat transfer coefficient, and the temperature distribution of the heat source is uniform, improving the heat transfer capacity. The secondary flow increases the cross-sectional area for flow of the flow, reducing the flow velocity of the main flow, thereby reducing the pressure drop. The inner side wall of the cover plate is inclined, allowing part of the working medium in the upstream to directly bypass to the downstream, reducing the pressure drop and at the same time improving the temperature uniformity of the heat source. Description of the Drawings

[0014] Figure 1 It is an assembly schematic diagram of the present invention.

[0015] Figure 2 It is an internal structure schematic diagram of one kind of the present invention.

[0016] Figure 3Another internal structure schematic diagram of the present invention.

[0017] Figure 4 Schematic diagram of the working fluid flow direction in the present invention.

[0018] Figure 5 Streamline distribution diagram in the heat dissipation fin in Embodiment 1.

[0019] Figure 6 is a comparison diagram of the flow velocity field distributions of the heat dissipation fin and the flat fin in Embodiment 1.

[0020] Figure 7 is a comparison diagram of the heat source temperature distributions of the heat dissipation fin and the flat fin in Embodiment 1.

[0021] Figure 8 Internal structure schematic diagram of the present invention.

[0022] Figure 9 Streamline distribution diagram in the heat dissipation fin in Embodiment 3.

[0023] Figure 10 Flow velocity field distribution diagram of the heat dissipation fin in Embodiment 3.

[0024] Figure 11 Temperature distribution diagram of the heat dissipation fin in Embodiment 3.

[0025] In the figure: 1 - fin substrate, 2 - heat dissipation fin, 3 - cover plate, 301 - convex part, 4 - flat fin. Specific embodiments

[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Embodiment 1

[0028] Figure 1 、 2A heat dissipation enhancement device using an array of heat dissipation fins is shown, which includes a fin substrate 1, heat dissipation fins 2, and a cover plate 3. The fin substrate 1 and the cover plate 3 enclose a hollow cavity with both ends open. One end of the hollow cavity is connected to a cooling medium supply device, and the other end is connected to a cooling medium recovery device. The cross-section of the heat dissipation fin 2 is an isosceles trapezoid, with the length of the long side being 3 mm, the length of the short side being 0.5 mm, and the thickness of a single fin being 0.5 mm. The heat dissipation fins 2 are located on the top of the fin substrate 1 and are distributed in the hollow cavity; the heat dissipation fins 2 perpendicular to the flow direction of the cooling medium are evenly distributed at equal intervals, and the heat dissipation fins 2 parallel to the flow direction of the cooling medium are evenly distributed at equal intervals and adjacent heat dissipation fins 2 are centrosymmetric. A secondary channel is formed between adjacent and parallel hypotenuses, with a secondary channel spacing of 0.3 mm, and a main channel is formed between adjacent long sides and short sides, with a main channel spacing of 0.5 mm.

[0029] Now, a comparison is made between the flow channels formed by the above trapezoidal heat dissipation fins and conventional straight fins. The trapezoidal fin array has a total of 10×19 fins. Right below the fins, there is a chip as a heat source, with a size of 24 mm×18 mm and a power of 250 W. The size of the cooling medium (working fluid) inlet is 19.5 mm×3 mm, the working fluid is pure water at 30 °C, and the inlet flow rate is 1 liter per minute. The straight fin structure consists of 19 slender straight fins arranged in parallel, with the same thickness, main channel width, device size, operating conditions, etc. as the trapezoidal fins.

[0030] During use, the bottom surface of the fin substrate 1 is in contact with the surface of the chip as the heat source, and thermal grease is applied between the two. The cooling medium flows through the channels formed by the fins in the heat dissipation device, taking away the heat on the fin substrate 1 and the heat dissipation fins 2, thereby achieving the purpose of cooling the chip. In the array distribution of the heat dissipation fins 2, the cooling medium in the main channel serves as the main flow, and the cooling medium in the secondary channel serves as the secondary flow. Since the secondary channel forms complementary angles with the flow direction of the cooling medium, as Figure 4 shown, the secondary flow periodically detaches from the main flow and then merges into the main flow, making the flow channel have a larger effective cross-sectional area for flow, a smaller pressure drop, and a uniform temperature distribution of the heat source.

[0031] Figure 5 Figure 12 is a streamline distribution diagram obtained after using CFD simulation. It can be seen from the figure that the flow in the main channel is not hindered at all, and a secondary flow is generated in the secondary channel. Figure 6 compares the flow channels formed by the trapezoidal fins and conventional straight fins in this embodiment, and shows the distribution of the velocity field under the same operating conditions. As Figure 6a can be seen, on both sides of the main channel in this embodiment, the flow velocity near the fins is relatively high and the boundary layer is relatively thin. In contrast, Figure 6b the flow in the straight fins shown in [reference] has a rapidly thickening boundary layer after entering the flow channel.

[0032] Due to the flow channels composed of trapezoidal fin structures having a larger effective cross-sectional area for fluid flow, compared with conventional flat fins, the pressure drop across the entire flow channel of the new design is smaller. Under the operating conditions described above, for the heat dissipation device using the new type of fins, the pressure drop across the entire flow channel is 903 Pa; while for the heat dissipation device using conventional flat fins, the pressure drop across the entire flow channel is 1022 Pa.

[0033] In terms of heat transfer performance, Figure 7 compares the temperature distributions of the heat source after using two types of fin structures in the heat dissipation device. As can be seen from the figure, using trapezoidal fins makes the temperature distribution of the heat source more uniform, and the maximum temperature is lower ( Figure 7a ). While obvious hot spots appear at the downstream of the flow channel for flat fins ( Figure 7b ). Specifically, after using trapezoidal fins, the maximum temperature of the heat source is 48.3 °C; while after using conventional flat fins, the maximum temperature of the heat source reaches 50.3 °C.

[0034] Embodiment 2

[0035] Figure 3 Disclosed is a heat dissipation enhancement device using an array of heat dissipation fins, including a fin substrate 1, heat dissipation fins 2, and a cover plate 3. The fin substrate 1 and the cover plate 3 enclose a hollow cavity with both ends open. One end of the hollow cavity is connected to a cooling medium supply device, and the other end is connected to a cooling medium recovery device. The cross-section of the heat dissipation fin 2 is an isosceles triangle, with the base length of 3 mm, the waist length of 1.7 mm, and the thickness of a single fin being 0.5 mm. The heat dissipation fins 2 are located on the top of the fin substrate 1 and distributed within the hollow cavity; the heat dissipation fins 2 perpendicular to the cooling medium flow direction are evenly distributed at equal intervals, and the heat dissipation fins 2 parallel to the cooling medium flow direction are evenly distributed at equal intervals and adjacent heat dissipation fins 2 are centrosymmetric. Secondary channels are formed between adjacent and parallel hypotenuses, with the secondary channel spacing being 0.3 mm, and main channels are formed between adjacent bases, with the main channel spacing being 0.5 mm.

[0036] Embodiment 3

[0037] To further improve the heat dissipation capacity of the heat dissipation device, as Figure 8 shown, a convex portion 301 is formed by the downward protrusion of the inner side wall of the cover plate 3, such that the gap between the inner side wall of the cover plate 3 and the top of the heat dissipation fins 2 becomes smaller along the fluid flow direction. The total length of the heat dissipation fins 2 in the working medium flow direction is 27.15 mm, while the length of the convex portion 301 in the working medium flow direction is 15.15 mm. The end face of the convex portion 301 close to the working medium outlet direction is flush with the end of the heat dissipation fins 2 close to the working medium outlet direction.

[0038] Figure 9It is the streamline distribution diagram obtained after using CFD simulation. As can be seen from the figure, some of the working fluid is upstream of the heat dissipation fin 2 and directly bypasses through the gap formed by the inner sidewall of the cover plate 3 and the top of the heat dissipation fin 2 to flow towards the outlet. The bypassed working fluid is blocked by the convex part 301 and converges into the downstream heat dissipation fin 2. Figure 10 It is the velocity field in the middle vertical section of the heat dissipation device. As can be seen from the figure, since some of the working fluid directly bypasses above the top of the heat dissipation fin 2, the velocity of the working fluid in the heat dissipation fin 2 is lower in the upstream part and higher in the downstream part.

[0039] Since the working fluid directly bypasses in the upstream part of the heat dissipation fin 2, it has a larger effective flow cross-sectional area and a lower pressure drop. Under the same operating conditions as those described in the previous Embodiment 1, after using the cover plate 3 with the convex part 301, the pressure drop in the entire flow channel is 739 Pa.

[0040] In terms of heat transfer performance, Figure 11 It is the temperature distribution of the heat source after using the cover plate 3 with the convex part 301. Compared with Figure 7a it can be seen that the temperature distribution of the heat source is more uniform. A region with a lower temperature appears in the middle of the heat source, which corresponds to the position where the working fluid is blocked by the convex part 301 and then converges downward into the heat dissipation fin 2. Therefore, the hot spot is divided into two, and the temperatures of both hot spots are relatively low. Specifically, the highest temperature of the heat source is 48.1 °C.

[0041] Although the present invention has been described herein with reference to several illustrative embodiments of the present invention, it should be understood that those skilled in the art can design many other modifications and embodiments that will fall within the scope of the principles and spirit disclosed in this application. More specifically, within the scope of this application's disclosure, the accompanying drawings, and the claims, various variations and improvements can be made to the components and / or the layout. In addition to the variations and improvements made to the components and / or the layout, other uses will also be apparent to those skilled in the art.

Claims

1. An enhanced heat dissipation device using an array of heat dissipation fins, characterized in that: it includes a fin substrate (1), heat dissipation fins (2) and a cover plate (3). The fin substrate (1) and the cover plate (3) enclose a hollow cavity with both ends open. One end of the hollow cavity is connected to a cooling medium supply device, and the other end is connected to a cooling medium recovery device; the heat dissipation fins (2) are trapezoidal or triangular, and the heat dissipation fins (2) are located at the top of the fin substrate (1) and distributed in the hollow cavity; the heat dissipation fins (2) perpendicular to the cooling medium flow direction are evenly distributed at equal intervals, and the heat dissipation fins (2) parallel to the cooling medium flow direction are evenly distributed at equal intervals and adjacent heat dissipation fins (2) are centrosymmetric; when the heat dissipation fin (2) is a triangular fin, the triangle is an isosceles triangle, the bottom side length is 3 mm, the waist length is 1.7 mm, and the thickness of a single fin is 0.5 mm; a secondary channel is formed between adjacent and parallel hypotenuses, the secondary channel spacing is 0.3 mm, and a main channel is formed between adjacent bottom sides, the main channel spacing is 0.5 mm; the inner side wall of the cover plate (3) is inclined, and the gap between it and the top of the heat dissipation fin (2) gradually decreases along the fluid direction. The inner side wall of the cover plate (3) bulges downward to form a convex part (301). The end face of the convex part (301) close to the working medium outlet direction is flush with the end of the heat dissipation fin (2) close to the working medium outlet direction; the bottom surface of the fin substrate (1) is in contact with the surface of the electronic component serving as the heat source, and the cooling medium flows through the channels formed by the fins in the heat dissipation device to take away the heat on the fin substrate (1) and the heat dissipation fins (2).

2. The enhanced heat dissipation device using an array of heat dissipation fins according to claim 1, characterized in that: when the heat dissipation fin (2) is a trapezoidal fin, the trapezoid is an isosceles trapezoid, the long side length is 1 - 3.5 mm, the short side length is 0.1 - 0.7 mm, and the thickness is 0.1 - 0.6 mm; a secondary channel is formed between adjacent and parallel hypotenuses, the secondary channel spacing is 0.1 - 0.4 mm, and a main channel is formed between adjacent long sides and short sides, the main channel spacing is 0.2 - 0.6 mm.

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