A power electronic device immersion phase change heat transfer structure

Abstract

The application discloses an immersion phase change heat exchange structure of a power electronic device, which comprises a heat dissipation substrate for being in contact with a heat source of the power electronic device, and a heat dissipation structure body vertically immersed in a phase change working medium, wherein the heat dissipation structure body comprises a plate structure and fin structures which are distributed on the plate structure at intervals, the fin structures are gradually inclined away from the plate structure along a height direction, tail portions of the fin structures are provided with concave arc structures, and the plate structure is provided with trapezoidal micro-channels in regions without the fin structures. The immersion phase change heat exchange structure can significantly improve a maximum heat flux density of phase change cooling and reduce structural thermal stress, effectively prevents thermal runaway of the power electronic device caused by excessively high temperature, and provides support for safe operation of the power electronic device and a power grid.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat exchange, in particular to an immersed phase change heat exchange structure for power electronic devices. BACKGROUND

[0002] In recent years, high-power power electronic devices such as insulated gate bipolar transistors have been continuously developed, showing a trend of higher and higher power levels and smaller and smaller device sizes. The heat generated during operation increases sharply, and the heat dissipation performance has become a key bottleneck restricting the reliability, service life and energy efficiency of the device. Traditional heat dissipation technologies (such as air cooling, liquid cooling, etc.) gradually expose the defects of insufficient heat transfer efficiency and poor temperature uniformity in high heat flux density scenarios. Immersed phase change cooling technology has become a research hotspot in the field of high-power heat dissipation due to its advantages of high heat capacity, low thermal resistance and utilization of phase change latent heat. This technology directly immerses the heat-generating device in an insulating working medium, absorbs a large amount of heat through the vaporization of the working medium, and then realizes continuous heat dissipation through condensation circulation. However, the existing immersed phase change heat dissipation structure still has problems such as low bubble detachment efficiency, single heat conduction path, and insufficient dynamic adaptability in actual application.

[0003] Currently, the main ways to enhance the immersed phase change cooling process are to optimize the surface microstructure modification of the heat sink (such as micro-column array, porous coating), but the change of micro-surface structure will bring about the difference of results, and currently different researchers will bring about completely different heat dissipation characteristics for the same micro-surface modification design; another main way to strengthen heat dissipation is to study the corresponding phase change material, and the current phase change material for immersed phase change cooling is mainly fluorocarbon compounds, but the cost is too high and has a certain impact on the environment. In addition, the existing technology lacks collaborative optimization of phase change working medium and heat dissipation structure, and fails to fully utilize the heat transfer potential of immersed phase change.

[0004] It should be noted that the information disclosed in the above background section is only for understanding the background of the present application, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] The main purpose of the present application is to overcome the defects in the background art, and to provide an immersed phase change heat exchange structure for power electronic devices, which improves the heat dissipation reliability and efficiency of high-power density power electronic devices and prevents thermal runaway.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] An immersed phase change heat exchange structure for power electronic devices, comprising:

[0008] a heat dissipation substrate for contacting a heat source of a power electronic device;

[0009] The main body of the heat dissipation structure is vertically immersed in the phase change working fluid, including a plate-like structure and fin-like structures spaced apart thereon. The fin-like structures gradually tilt away from the plate-like structure along the height direction. The tail of the fin-like structure is provided with a concave arc-shaped structure. The plate-like structure is provided with trapezoidal microchannels in the area not covered by the fin-like structure.

[0010] Furthermore, the tilt angle of the fin-like structure is 10°-20°.

[0011] Furthermore, the central angle corresponding to the arc shape at the tail of the fin-like structure is 30°-45°.

[0012] Furthermore, the surface of the fin-like structure is distributed with circular holes, which are obtained by Boolean subtraction of cylinders with a radius of 0.1-0.5 mm in the direction perpendicular to the ground and the axis of the fin-like structure, and the spacing between the holes is 1-2 mm.

[0013] Furthermore, the trapezoidal microchannel forms a channel opening at the upper base of the trapezoid and a channel bottom at the lower base of the trapezoid.

[0014] Furthermore, the trapezoidal microchannel has an inclination angle of 20°-30°, an upper base length of 0.05-0.15mm, and a lower base length of 0.25-0.35mm.

[0015] Furthermore, the width of the fin structure is set to 2-6 mm according to the power of the heat source.

[0016] Furthermore, the material of the main body of the heat dissipation structure is selected from copper, copper alloy, aluminum or aluminum alloy.

[0017] The present invention has the following beneficial effects:

[0018] This invention, through an innovative immersion phase change heat transfer structure design, combined with the tilt angle of the finned structure, the arc shape of the tail, and the surface perforation layout, effectively optimizes bubble detachment efficiency and liquid working fluid replenishment capability. The tilted finned structure blocks the continuous growth of the gas film and accelerates bubble detachment using the tilt angle; the arc-shaped tail design increases the nucleation boiling points and promotes liquid reflux through capillary action; and the circular perforations on the surface inhibit gas film formation and guide the discharge of microbubbles, thus avoiding localized dry burning. Simultaneously, the trapezoidal microchannels on the plate-like structure enhance the rapid flow of the liquid working fluid to high heat flux density regions through capillary effect, significantly improving the latent heat utilization efficiency of the phase change. Compared with traditional heat dissipation structures, this design achieves an efficiency improvement of over 5% with the same heat dissipation area under high power density conditions, breaking through the heat dissipation bottleneck of high-power power electronic devices and significantly improving the heat dissipation performance and operational reliability of high-power density power electronic devices under immersion phase change cooling conditions.

[0019] The special-shaped immersed phase change heat dissipation structure is designed, and the dynamic interaction of the heat dissipation structure and the phase change working medium is further optimized, so that the problems of single heat conduction path and insufficient dynamic adaptability in traditional immersed cooling are solved. The width, inclination angle of the fin structure and the geometric parameters of the trapezoidal microchannel are designed in detail according to the heat source power and fluid characteristics, which not only reduces the structural thermal stress, but also improves the maximum heat flux density carrying capacity. The synergistic effect of this multi-scale structure innovation and working fluid flow ensures the uniformity and stability of the heat dissipation process, effectively prevents device thermal runaway, and provides technical support for reliable operation of high-power power electronic equipment.

[0020] Other beneficial effects in the embodiments of the present application will be further described below. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of an immersed phase change heat transfer structure of a power electronic device in the embodiments of the present application.

[0022] Figure 2 is a front view of the distribution of the fin structure in the embodiments of the present application.

[0023] Figure 3 is an enlarged schematic diagram of the arc-shaped structure at the tail end of the fin structure and the trapezoidal microchannel in the embodiments of the present application.

[0024] Figure 4 is a schematic diagram of the hole distribution of the fin structure in the embodiments of the present application.

[0025] Figure 5(a) is a simulation result of a traditional air-cooled plate-fin type heat sink structure under high heat flux density.

[0026] Figure 5(b) is a simulation result of the embodiments of the present application under high heat flux density.

[0027] The reference signs are as follows: 1 is a heat dissipation substrate, 2 is a heat sink fin, 3 is a fin structure on the heat sink fin, 31 is a circular hole on the fin structure, 32 is an arc-shaped structure at the tail end of the fin structure, 4 is a trapezoidal microchannel on the heat sink fin, 41 is the upper base of the trapezoidal microchannel, and 42 is the lower base of the trapezoidal microchannel. DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below. It should be emphasized that the following description is only exemplary and is not intended to limit the scope of the present application and its applications.

[0029] It is to be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, the connection can be for fixing or for coupling or for communication.

[0030] It is to be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate directions or positions based on the directions or positions shown in the drawings, and are used for the purpose of facilitating the description of the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the present application.

[0031] In addition, the terms "first", "second", are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0032] The heat dissipation structure of the current phase change cooling technology still mainly follows the heat dissipation structure of air cooling and liquid cooling technology, and the advantages of phase change cooling are not fully played, and there is a deficiency in the heat dissipation efficiency, and even a local dryness is too high to cause a device temperature to exceed a limit and the like. The present application combines the principles of bubble dynamics and capillary action and the like to propose a new immersion type phase change cooling heat dissipation structure capable of avoiding local dry burning.

[0033] Referring to Figures 1 to 4 The embodiment of the present application provides an immersion type phase change heat transfer structure of a power electronic device, which is used as a heat sink of the power electronic device and comprises: a heat dissipation substrate 1 used for contacting a heat source of the power electronic device; a heat dissipation structure main body vertically immersed in a phase change working medium, comprising a plate-shaped structure as a heat sink fin 2 and fin-shaped structures 3 distributed at intervals thereon; the fin-shaped structures 3 gradually tilt away from the plate-shaped structure along the height direction, and the tail part of the fin-shaped structures 3 is provided with an arc-shaped structure 32 concave inward; the plate-shaped structure is provided with trapezoidal micro-channels 4 in the region not covered by the fin-shaped structures 3. The arc-shaped tail part of the fin-shaped structures 3 promotes the replenishment of the liquid phase working medium through capillary action, and the tilt angle and distribution spacing thereof are used for accelerating the bubble separation, and the trapezoidal micro-channels 4 enhance the flow of the liquid phase working medium to the heat source region through capillary action, and quickly replenish to the root part of the plate-shaped structure where the phase change is most intense. Thus, the immersion type gas-liquid phase change cooling process is strengthened, local dry burning is avoided, and the heat dissipation efficiency is improved.

[0034] In a preferred embodiment, the inclination angle of the fin structure 3 is 10-20°.

[0035] In a preferred embodiment, the central angle of the arc structure 32 at the tail of the fin structure 3 is 30-45°.

[0036] Referring to Figure 1 and Figure 4 In a preferred embodiment, the surface of the fin structure 3 is provided with circular holes 31, which are obtained by performing a Boolean subtraction operation on the fin structure 3 and a cylinder with a radius of 0.1-0.5 mm perpendicular to the horizontal surface, and the distance between the holes is 1-2 mm. The circular holes 31 are used to suppress the formation of gas film and guide the discharge of micro-bubbles. The circular holes can be through holes with a depth consistent with the thickness of the fin structure, and the axis of the cylinder is perpendicular to the horizontal surface to guide the discharge of bubbles.

[0037] Referring to Figure 3 In a preferred embodiment, the trapezoidal micro-channel forms an opening of the micro-channel at the upper base of the trapezoid and a bottom of the micro-channel at the lower base of the trapezoid. In a more preferred embodiment, the inclination angle of the trapezoidal waist of the trapezoidal micro-channel 4 is 20-30°, the length of the upper base 41 is 0.05-0.15 mm, and the length of the lower base 42 is 0.25-0.35 mm.

[0038] In some embodiments, the width of the fin structure 3 is set to 2-6 mm according to the power of the heat source.

[0039] In some embodiments, the material of the heat dissipation structure body is selected from copper, copper alloy, aluminum, or aluminum alloy.

[0040] In the power electronic device immersion phase change heat transfer structure proposed by the present application, the arc tail of the fin structure cooperates with the trapezoidal micro-channel to increase the nucleate boiling point and rapidly replenish the liquid phase, so that the heat dissipation efficiency is improved by more than 5% compared with the traditional plate fin structure. The immersion phase change cooling heat dissipation structure of the present application can significantly improve the maximum heat flux density of phase change cooling and reduce the structural thermal stress, effectively prevent the thermal runaway of power electronic devices caused by excessive temperature, and provide support for the safe operation of power electronic devices and power grids.

[0041] The specific embodiments of the present application are further described below.

[0042] The structural schematic diagram is as shown in Figure 1As shown, the heat sink mainly consists of two parts, including a heat dissipation substrate and a heat dissipation structure main body. The heat sink is vertically immersed in a large volume of phase change material, and the gas-liquid separation is achieved by using the natural buoyancy of the bubbles, and the influence of the heat source and the heat sink on the temperature of the distant liquid can be ignored. The heat dissipation structure main body includes a plate structure and a fin-shaped structure distributed thereon in an interval, and a trapezoidal microchannel is left on the plate structure of the main body. The following introduction is under the condition that the heat sink is vertically placed, and the arc-shaped opening of the fin-shaped structure is reversed towards the ground. The phase change material can be high-insulation low-boiling fluorinated liquid (such as FC-72, Novec 7100) or deionized water (adapted to the waterproof requirement of the device).

[0043] Figure 2 is a front view of the fin-shaped structure distribution of the embodiment of the application. Figure 3 is an enlarged schematic view of the arc-shaped structure at the tail end of the fin-shaped structure and the trapezoidal microchannel. All the fin-shaped structures in the heat sink can be the same, and the height gradually increases with the height from the ground. The tail of the fin-shaped structure gradually deviates as the height from the ground increases, and the inclination angle is between 10°-20°. The width is set in the range of 2-6mm according to the size of the heat source power. There is an arc-shaped structure at the tail of the fin-shaped structure, and the corresponding central angle range is between 30°-45°. The radius of the fin-shaped structure perpendicular to the ground in the direction of the axis is a cylindrical with a radius of 0.1-0.5mm, and the Boolean subtraction operation is performed to obtain a hole with a spacing of 1-2mm. Figure 4 is a schematic view of the hole distribution of the fin-shaped structure of the embodiment of the application.

[0044] The area on the plate structure of the main body without fin-shaped structure is provided with a trapezoidal microchannel, and the corresponding inclination angle is between 20°-30°. The upper base length of the trapezoid is between 0.05-0.15mm, and the lower base is between 0.25-0.35mm. A certain gap is left between the microchannels.

[0045] The material of the heat sink main body structure and the fin-shaped structure is copper, copper alloy, aluminum, aluminum alloy, etc.

[0046] In the heat dissipation process, the fins protrusions of the present application can block the growth of the bubble film generated by the phase change material after absorbing heat under high heat flux, making it difficult to gather into a coherent gas film, and a certain inclination angle can promote the rapid detachment of the bubble. In addition, the arc-shaped design of the tail end can increase the nucleate boiling site and also has a capillary effect to promote the rapid entry of surrounding liquid into the arc-shaped area and make the bubble detach. Under high heat flux, the bubbles are relatively coherent and mostly in the form of foam, and when the gas film is formed on the certain slope of the fin structure, the circular holes in the middle section of the fin structure can allow some small bubbles to pass through the holes and be discharged, thereby inhibiting the formation of the gas film and avoiding the formation of wall dry-out phenomenon. In the trapezoidal microchannel area without fin structure coverage, the liquid around the heat sink is quickly replenished to the root of the plate-shaped structure where the phase change is most intense through the capillary effect, improving the heat dissipation performance. Figure 5(a) shows the simulation results of a traditional air-cooled plate-fin heat sink structure under high heat flux, and Figure 5(b) shows the simulation results of the present application under high heat flux. According to the simulation experiment, compared with the traditional air-cooled plate-fin heat sink structure, under the same heat dissipation area, as the power density increases, the heat dissipation efficiency increases, and under high heat power density, the present application can achieve a heat dissipation efficiency increase of 5% or more. The heat transfer coefficient or maximum heat flux carrying capacity is superior to the traditional plate-fin structure. Compared with existing heat dissipation structures, the structure of the present application realizes rapid bubble detachment, rapid liquid replenishment, and other effects through innovative design, improves the heat dissipation efficiency of immersion phase change cooling, and breaks through the heat dissipation bottleneck of high-power power electronic devices.

[0047] The above further describes the present application in conjunction with specific / preferred embodiments, and cannot be deemed to limit the specific implementation of the present application to these descriptions. For those skilled in the art to which the present application belongs, without departing from the concept of the present application, they can make several substitutions or variations to the described embodiments, and these substitutions or variations shall be deemed to fall within the protection scope of the present application. In the description of the present application, the description of the terms "an embodiment", "some embodiments", "a preferred embodiment", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are contained in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the case of no mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples. Although the embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. An immersion phase change heat transfer structure for power electronic devices, characterized in that, include: A heat dissipation substrate, used to contact the heat source of power electronic devices; The main body of the heat dissipation structure is vertically immersed in the phase change working fluid, including a plate-like structure and fin-like structures spaced apart on it. The fin-like structures gradually tilt away from the plate-like structure along the height direction. The tail of the fin-like structure is provided with a concave arc-shaped structure. The surface of the fin-like structure is distributed with circular holes. The plate-like structure has trapezoidal microchannels in the areas not covered by the fin-like structures. The trapezoidal microchannels form a channel opening at the upper bottom of the trapezoid and a channel bottom at the lower bottom of the trapezoid.

2. The immersion phase change heat transfer structure according to claim 1, characterized in that, The tilt angle of the fin-like structure is 10°-20°.

3. The immersion phase change heat transfer structure according to claim 1, characterized in that, The central angle corresponding to the arc shape at the tail of the fin-like structure is 30°-45°.

4. The immersion phase change heat transfer structure according to claim 1, characterized in that, The circular holes are obtained by Boolean subtraction of cylinders with a radius of 0.1-0.5 mm in the direction perpendicular to the ground and the axis of the fin structure, and the spacing between the holes is 1-2 mm.

5. The immersion phase change heat transfer structure according to claim 1, characterized in that, The trapezoidal microchannel has an inclination angle of 20°-30°, an upper base length of 0.05-0.15mm, and a lower base length of 0.25-0.35mm.

6. The immersion phase change heat transfer structure according to claim 1, characterized in that, The width of the fin structure is set to 2-6 mm according to the power of the heat source.

7. The immersion phase change heat transfer structure according to any one of claims 1 to 6, characterized in that, The material of the main body of the heat dissipation structure is selected from copper, copper alloy, aluminum or aluminum alloy.

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