Rib array microchannel heat sink with top gap

Abstract

The present application belongs to the field of electronic device heat dissipation, and discloses a rib array micro-channel heat sink with top gap, which comprises a rectangular micro-channel, and a rib array is arranged on the micro-channel flow channel, wherein the rib array comprises a plurality of rib plates; the height of the rib array is lower than the side wall of the micro-channel, so that a top gap is formed between the upper surface of the rib plate and the upper surface of the micro-channel; and the top gap coefficient ε satisfies 0.05≤ε≤0.2. The present application improves the traditional micro-channel heat sink by arranging the airfoil rib array with top gap in the micro-channel heat sink. Due to the structural characteristics of the airfoil rib plate and the top gap between the airfoil rib plate and the upper surface of the micro-channel, the secondary flow perpendicular to the main flow direction can be generated during the flow of the fluid in the micro-channel, and the flow resistance is reduced, so that the heat exchange effect and the comprehensive performance of the micro-channel heat sink are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electronic device heat dissipation, and more particularly relates to a rib array micro-channel heat sink with a top gap. BACKGROUND

[0002] Electronic components are developing towards high integration and miniaturization at a high speed, which makes the heat dissipation problem between electronic components particularly prominent. The heat dissipation problem has become one of the main problems restricting the development of the microelectronic field. In the field of chip heat dissipation, micro-channel heat sink technology stands out from a series of heat dissipation technologies due to its compact structure, strong heat exchange capacity and ability to mass production, etc.

[0003] Micro rib array is a new type of micro-channel structure in which a group of ribs is arranged in the channel to replace part of the channel wall surface, and the heat transfer is enhanced by the disturbance of the group of ribs to the fluid. Because it has a larger surface-to-volume ratio and a more prominent disturbance effect on the cooling medium, it has better heat transfer performance. However, the presence of the group of ribs greatly increases the flow resistance, which to some extent restricts the development of micro-channel heat sinks. Therefore, it is of great significance to improve the comprehensive performance of micro-channel heat sinks by improving the heat transfer effect and reducing the flow resistance of micro-channel heat sinks with rib arrays. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the present application provides a rib array micro-channel heat sink with a top gap, which aims to effectively reduce the flow resistance in the micro-channel heat sink with rib array, and improve the heat transfer effect and comprehensive performance of the micro-channel heat sink.

[0005] To achieve the above-mentioned purpose, the present application provides a rib array micro-channel heat sink with a top gap, comprising a rectangular micro-channel, a rib array is arranged on the micro-channel flow passage, and the rib array comprises a plurality of ribs; the height of the rib array is lower than the side wall of the micro-channel, so that a top gap is formed between the upper surface of the rib and the upper surface of the micro-channel.

[0006] The top gap coefficient ε is represented by the following formula:

[0007]

[0008] Wherein, h is the height of the rib array, H ch is the height of the micro-channel side wall, and ε satisfies 0.05≤ε≤0.2.

[0009] As a further preferred, the top gap coefficient ε satisfies 0.05≤ε≤0.1.

[0010] As a further preferred, the cross-sectional shape of the rib is airfoil-shaped, and the fluid flows into the micro-channel along the leading edge of the airfoil and flows out along the trailing edge of the airfoil.

[0011] As further preferred, the transverse spacing S of the airfoil fin arrangement in the rib array satisfies T

[0012] As further preferred, the longitudinal spacing S of the airfoil fin arrangement in the rib array satisfies L

[0013] As further preferred, the heat flux is applied to the bottom surface of the microchannel, i.e. the side surface without the top gap, during use.

[0014] As further preferred, the microchannel heat sink is applicable to the Reynolds number Re range of 200≤Re≤1600.

[0015] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0016] 1. The presence of the top gap in the microchannel of the present application will cause the fluid to generate disturbance perpendicular to the main flow direction during the whole process of flowing through the rib, which is not possessed by the channel without the top gap. The secondary flow caused by the top gap can greatly enhance the fluid disturbance, and strengthen the convective heat transfer between the fluids and between the fluids and the wall surface. In addition, the presence of the top gap can destroy the development of the boundary layer on the two sides of the rib, so that the fluid velocity near the rib wall surface is greatly increased, realizing the improvement of the heat transfer effect and comprehensive performance of the microchannel heat sink.

[0017] 2. Compared with the rib array microchannel without the top gap, the rib array microchannel with the top gap has other advantages including easier processing and manufacturing, easier assembly, less required materials, lighter weight, etc.

[0018] 3. The adverse effects of the reduction of the top gap on heat transfer include the reduction of the fluid flow velocity in the top gap and the weakening of the disturbance perpendicular to the main flow direction; while the beneficial effects of the reduction of the top gap on heat transfer include the increase of the heat transfer area and the increase of the flow velocity on both sides of the rib. Accordingly, the present application designs the top gap coefficient ε to satisfy 0.05≤ε≤0.2, so that the microchannel still has strong vortex and secondary flow while having larger heat transfer area and larger flow velocity on both sides of the rib, and the heat transfer effect is best.

[0019] 4. The rib of the present application adopts an airfoil as the cross-sectional shape, which can reduce the flow resistance; the fluid flows into the microchannel along the leading edge of the airfoil and flows out along the trailing edge of the airfoil, so as to fully exert the role of the airfoil rib in delaying the separation of the fluid on its surface, and make the area subjected to the flushing of the high-speed fluid near the wall surface larger, thereby effectively strengthening the heat transfer. ​​

[0020] 5、The present application adjusts the rib array arrangement parameter S according to the size of the airfoil rib chord length c T and S L Adjusts accordingly, and adjusts the top gap coefficient ε between 0.05 to 0.2 according to the actual situation, effectively reduces the flow resistance in the micro-channel heat sink with rib array, so as to realize the improvement of the micro-channel heat sink heat exchange effect and comprehensive performance. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The three-dimensional structure and size of the airfoil rib array micro-channel with top gap of the embodiment of the present application are shown in the figure;

[0022] Figure 2 The plane size of the airfoil rib array micro-channel with top gap of the embodiment of the present application is shown in the figure;

[0023] Figure 3 The change relationship diagram between the flow and heat exchange performance of the micro-channel heat sink and the top gap coefficient ε and the Reynolds number Re is shown in the figure, wherein (a) is the change relationship diagram between the resistance coefficient f and the top gap coefficient ε and the Reynolds number Re, and (b) is the change relationship diagram between the Nusselt number Nu and the top gap coefficient ε and the Reynolds number Re;

[0024] Figure 4 The change relationship diagram between the comprehensive evaluation coefficient η of the micro-channel heat sink and the top gap coefficient ε and the Reynolds number Re is shown in the figure.

[0025] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein: 1-micro-channel, 2-rib array. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0027] The rib array micro-channel heat sink with top gap provided by the embodiment of the present application, as shown in Figure 1 and Figure 2 , includes a rectangular micro-channel 1, and a rib array 2 is arranged on the flow channel of the micro-channel 1, the rib array 2 includes a plurality of rib plates arranged in a specific manner, and NACA 65-019 airfoil is preferably used as the cross-sectional shape in the embodiment.

[0028] The height of the rib array is lower than the side wall surface of the micro channel, so that a top gap is formed between the upper surface of the rib and the upper surface of the micro channel. The fluid flows into the micro channel along the leading edge of the airfoil and flows out along the trailing edge of the airfoil, so that the airfoil rib delays the separation of the fluid on the surface, the area of the fluid subjected to the high-speed flow near the wall surface is larger, and the heat exchange is effectively enhanced.

[0029] The present application improves the conventional micro channel heat sink by arranging the airfoil rib array with a top gap in the micro channel heat sink. Due to the streamlined structure of the airfoil rib and the top gap between the upper surface of the airfoil rib and the upper surface of the micro channel, the coupling flow mode of the fluid in the upper space of the airfoil rib and on both sides of the rib forms a secondary flow perpendicular to the main flow direction during the whole process of flowing through the rib, greatly enhances the disturbance of the fluid, and reduces the flow resistance, thereby effectively improving the heat exchange effect and comprehensive performance of the micro channel heat sink.

[0030] The height of the airfoil rib array is h, the height of the side wall of the micro channel is H ch , and the top gap coefficient is ε, so that the top gap coefficient ε can be expressed as: ε should satisfy 0.05≤ε≤0.2. And the heat flux density should be applied to the side surface of the micro channel without top gap, that is, the bottom surface of the micro channel as shown in Figure 1 .

[0031] The present application is designed according to the arrangement parameters S T and S L of the airfoil rib array and the top gap coefficient ε, wherein the chord length c of the airfoil, the width W ch , the length L, the height H ch , the thickness W s of the side wall of the micro channel and the bottom thickness H s can be adjusted according to the actual situation, and the heat exchange effect and comprehensive performance of the micro channel heat sink are not greatly affected.

[0032] Figure 2 It is a top view of the airfoil rib array micro channel with a top gap. The transverse spacing S T of the airfoil rib array and the chord length c of the airfoil satisfy The longitudinal spacing S L of the airfoil rib array and the chord length c of the airfoil satisfy

[0033] Figure 3 (a) in the figure is a variation relationship diagram of the resistance coefficient f and the top gap coefficient ε and the Reynolds number Re. ε=0 represents no top gap, that is, the rib height is equal to the height of the micro channel flow passage. From Figure 3As can be seen from Fig. 2 (a), the resistance coefficient of the microchannel is smaller when ε = 0.2 and ε = 0.3 than when Re is the same. When ε = 0.05 and ε = 0.1, the resistance coefficient of the microchannel is similar to that of the microchannel without the top gap when Re < 400. Only when Re > 400, the resistance coefficient of the microchannel is greater than that of the microchannel without the top gap.

[0034] Figure 3 As can be seen from Fig. 2 (b), when Re is the same, the Nu of the microchannel with ε = 0.3 is smaller than that of the microchannel without the top gap. The Nu of the microchannel with other ε values is obviously greater than that of the microchannel without the top gap. When ε = 0.1 and Re = 800, the Nu of the microchannel with the wing-shaped rib array is 124.5, which is increased by 16.9% than that of the microchannel without the top gap. This is because the coupling flow mode of the fluid in the space above the rib and the two sides of the rib forms a secondary flow perpendicular to the main flow direction, greatly enhances the disturbance of the fluid, and strengthens the convective heat transfer between the fluid and the wall. In summary Figure 3 As can be seen from Fig. 2 (a) and (b), the presence of the top gap can greatly improve the overall Nusselt number of the microchannel without increasing the resistance coefficient or even reducing the resistance coefficient.

[0035] Figure 4 In order to comprehensively evaluate the relationship between the coefficient η and the Reynolds number Re and the top gap coefficient ε, a graph is provided. The comprehensive evaluation coefficient η is commonly used to comprehensively evaluate the influence of various factors on the overall heat transfer performance of the heat sink. The greater the η, the higher the comprehensive performance of the heat sink. The expression is as follows:

[0036]

[0037] In the formula, Nu0 and f0 are the Nusselt number and the resistance coefficient of the rectangular flat microchannel without the rib array as a comparison standard. When the top gap coefficient is 0.05 ≤ ε ≤ 0.2, the comprehensive evaluation coefficient of the wing-shaped rib array microchannel with the top gap is greater than that of the wing-shaped rib array microchannel without the top gap. When ε = 0.1 and Re = 800, the comprehensive evaluation coefficient of the wing-shaped rib array microchannel is 3.2, which is increased by 320% than that of the rectangular flat microchannel without the rib array and is increased by 15.1% than that of the wing-shaped rib array microchannel without the top gap. This shows that the presence of the top gap can effectively improve the comprehensive performance of the wing-shaped rib array microchannel heat sink.

[0038] The wing-shaped rib array microchannel heat sink of the present application can ensure that the ratio of the transverse spacing S T to the chord length c of the wing-shaped rib array is in the range of 0.4 to 0.6, and the ratio of the longitudinal spacing S LWhen the ratio of the chord length c of the airfoil to the width of the micro-channel heat sink is in the range of 0.6-1 and the top gap coefficient is in the range of 0.05-0.2, other parameters of the micro-channel heat sink can be adjusted according to actual application, for example, the length and the inlet width of the micro-channel heat sink can be selected according to actual working environment so as to improve the adaptability to working conditions. The rectangular micro-channel heat sink and the airfoil rib array in the application can be manufactured, processed and assembled for use after inspection, or can be integrally formed.

[0039] In summary, by designing the top gap and improving the key rib shape, arrangement and specific size of the top gap in the micro-channel heat sink, the flow resistance in the micro-channel heat sink with rib array is effectively reduced, so that the heat exchange effect and comprehensive performance of the micro-channel heat sink are improved. The micro-channel heat sink is suitable for the Reynolds number Re (Re=U×D h / υ, U is the flow velocity, D h is the characteristic diameter of the micro-channel inlet and outlet, and υ is the kinematic viscosity coefficient of the fluid) in the range of 200≤Re≤1600.

[0040] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the application and is not intended to limit the application. Any modification, equivalent replacement and improvement within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A ribbed microchannel heat sink with a top gap, characterized in that, The device includes a rectangular microchannel with a rib array on the flow channel. The rib array includes multiple ribs. The cross-sectional shape of the ribs is airfoil-shaped. Fluid flows into the microchannel along the leading edge of the airfoil and flows out along the trailing edge of the airfoil. The height of the rib array is lower than the sidewall of the microchannel, so that a top gap is formed between the upper surface of the ribs and the upper surface of the microchannel. Top gap coefficient It can be expressed by the following formula: in, h The height of the rib formation. The microchannel sidewalls are high. Satisfying 0.05≤ ≤0.2; When in use, the heat flux density is applied to the bottom surface of the microchannel, that is, the side surface without the top gap; Lateral spacing of airfoil ribs in rib array chord length of airfoil rib Between satisfy ; Longitudinal spacing of airfoil ribs in rib array chord length of airfoil rib Between satisfy .

2. The ribbed microchannel heat sink with a top gap as described in claim 1, characterized in that, Top gap coefficient Satisfying 0.05≤ ≤0.

1.

3. The ribbed microchannel heat sink with a top gap as described in claim 1 or 2, characterized in that, The Reynolds number suitable for this microchannel heat sink Re The range is 200≤ Re ≤1600.

Images