A composite microstructure surface with sidewall-coupled microtubes to enhance boiling performance

Abstract

The present invention discloses a composite microstructure surface with sidewall-coupled microtubes for enhancing boiling performance. The surface is based on a regularly arranged microcolumn array, and a number of microcolumn units are arranged on a microcolumn substrate. By symmetrically opening microtubes extending to the top surface of the microcolumns on the microcolumns, the orderly coupling of the microcolumns and microtubes is achieved, and a three-level liquid replenishment system is constructed, which is liquid supply channel-groove-microtube from macro to micro, thereby enhancing the liquid replenishment capacity of the microstructure surface, improving the critical heat flux density of the surface, and delaying the occurrence of boiling crisis; the microcolumn units distributed in the array can effectively adjust the growth size of the bubbles, and the liquid supply channels between the arrays can effectively alleviate the lateral merging between the bubbles, delay the occurrence of film boiling, and maintain the stability of efficient nucleate boiling heat exchange. In addition, the composite microstructure surface proposed by the present invention is processed and formed in one step by deep silicon etching, and the processing technology is simple, which can realize large-scale commercial production and has high economic benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of phase change enhanced heat transfer, relates to a boiling heat transfer enhancement technology, and specifically relates to a composite microstructure surface with sidewall coupled microtubes for enhancing boiling performance. Background Art

[0002] High-heat flux devices such as high-power light-emitting diodes, high-performance servers, and gallium nitride power devices typically require high-performance phase-change cooling systems to maintain their safe operation. Boiling heat transfer is the foundation for achieving this high-performance phase-change cooling system. However, the increasing integration and power density of high-heat flux devices in recent years has brought new challenges to cooling system design. Traditional boiling heat transfer technology has struggled to meet the increasing heat dissipation demands. Therefore, enhancing boiling heat transfer performance to meet these demands has become a key strategy for addressing the application bottleneck of high-performance phase-change cooling systems.

[0003] The technical solution of processing microstructures on the surface can effectively enhance the boiling heat transfer performance. Among them, processing micro-column structures on the heat transfer substrate through methods such as wire cutting and etching can effectively increase the heat transfer area and the surface's fluid replenishment capacity, thereby improving the surface's boiling heat transfer performance. In addition, the micro-column structure itself has the characteristics of high structural strength and good stability, making it easy to achieve batch processing of the surface. Therefore, the micro-column structure surface has good application prospects in the field of boiling heat transfer and is an effective technical solution for improving the heat transfer efficiency of the cooling system.

[0004] However, micropillar surfaces also have some drawbacks that restrict their application and development. For example, in high-heat flux heat transfer areas, the large number of bubbles generated on the micropillar surface easily clogs the liquid supply channels, thereby weakening the liquid supply capacity. This limits the further improvement of the surface critical heat flux and boiling heat transfer coefficient, restricting the application and development of micropillar surfaces. Therefore, how to improve and enhance the liquid supply capacity of micropillar surfaces, further enhance the boiling heat transfer performance of microstructured surfaces, and delay the onset of boiling crisis has become the key to promoting the large-scale application of microstructured surfaces. Summary of the Invention

[0005] The present invention aims to provide a composite microstructure surface with sidewall-coupled microtubes for enhancing boiling performance, which improves the boiling heat transfer performance of the surface by effectively improving the liquid replenishment capacity of the microstructure surface.

[0006] The present invention is achieved through the following technical solutions:

[0007] A sidewall-coupled microtube-enhanced boiling performance composite microstructure surface comprises a microcolumn substrate and a plurality of microcolumn units distributed in an array on the microcolumn substrate, wherein the gaps between adjacent microcolumn units constitute liquid feed channels of the sidewall-coupled microtube-enhanced boiling performance composite microstructure surface;

[0008] The microcolumn unit is composed of a plurality of microcolumns distributed in an array, the gaps between adjacent microcolumns are grooves, and the width of each groove is the same; microtubes extending to and penetrating the top surface of the microcolumn are symmetrically opened on each side wall surface of each microcolumn, and the microtubes on each side wall surface of each microcolumn are distributed at equal intervals.

[0009] Furthermore, the microtubes are distributed in the upper half of each microcolumn and extend through the top surface of the microcolumn, and the length of the microtubes is half of the height of the microcolumn.

[0010] Furthermore, the microcolumns are square columns with a width of 60 to 80 μm and a height of 100 to 140 μm.

[0011] Furthermore, each side wall surface of the microcolumn is an inclined surface, and the angle A between each side wall surface of the microcolumn and the top surface is the same, and the angle A is 88.8 degrees to 89.2 degrees.

[0012] Furthermore, the microtube is a circular tube with a diameter of 3 to 5 μm.

[0013] Furthermore, the sum of the width of the liquid supply channel and the width of the adjacent microcolumn unit on one side is 1000 μm, and the width of the liquid supply channel is 100-400 μm.

[0014] Furthermore, the width of the internal channel of the microcolumn unit is 20-40 μm.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects:

[0016] The composite microstructured surface with sidewall-coupled microtubes for enhanced boiling performance proposed in this paper is based on a regularly arranged micropillar array. Several micropillar units are arranged on a micropillar base, and microtubes are symmetrically arranged on the sidewalls of each micropillar, extending to the top surface of the micropillar. Through the orderly coupling of micropillars and microtubes, a three-stage liquid replenishment system is first constructed, from the macro to the micro level: liquid supply channel-channel-microtube. This strengthens the liquid replenishment capacity of the microstructured surface, effectively increases the critical heat flux density of the surface, delays the occurrence of boiling crisis, and achieves a synergistic enhancement of the boiling heat transfer performance of the microstructured surface at multiple scales.

[0017] Secondly, the arrayed microcolumns effectively regulate the growth size of bubbles, and the liquid feed channels between the arrays effectively mitigate lateral merging of bubbles, thereby delaying the occurrence of heat transfer degradation and effectively maintaining the stability of efficient nucleate boiling heat transfer. Furthermore, the macroscale liquid feed channels serve as the main artery for liquid replenishment of the microcolumns, providing sufficient liquid supply for the gas-liquid phase transition of each microcolumn.

[0018] Furthermore, the length of the microtube is located in the upper half of the side wall of the microcolumn. The microtube can serve as a capillary fluid replenishment channel to re-wet the channel, avoiding the occurrence of bubble growth that causes the entire channel to be blocked, and effectively ensuring the smooth fluid replenishment inside the microcolumn unit, effectively improving the liquid supply capacity of the microstructure surface, thereby improving the boiling heat transfer performance of the surface.

[0019] In addition, the composite microstructure surface proposed in the present invention is formed in one step by deep silicon etching, and the processing technology is simple, which can realize large-scale commercial production and has high industrialization potential and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the surface structure of the composite microstructure with sidewall-coupled microtubes for enhancing boiling performance according to the present invention;

[0021] Figure 2 It is a schematic diagram of the local structure of the microcolumn unit of the present invention;

[0022] Figure 3 is a front view of the microcolumn of the present invention;

[0023] Figure 4 is a top view of the microcolumn of the present invention;

[0024] Figure 5 This is an oblique scanning electron microscope view of the surface of the composite microstructure with sidewall-coupled microtubes for enhanced boiling performance according to Example 1 of the present invention;

[0025] Figure 6 This is a comparison chart of the boiling curves of Example 1 of the present invention and a traditional microstructure surface with the same structural dimensions;

[0026] Among them, 1-microcolumn matrix; 2-liquid supply channel; 3-microcolumn unit; 4-microcolumn; 5-microtube; 6-groove. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0028] See also Figure 1 The sidewall-coupled microtubule-enhanced boiling performance composite microstructure surface of the present invention comprises a microcolumn substrate 1, a liquid supply channel 2, and microcolumn units 3. The microcolumn units 3 are arranged in an array on the microcolumn substrate 1, and the gaps between adjacent microcolumn units 3 serve as the liquid supply channels 2 of the sidewall-coupled microtubule-enhanced boiling performance composite microstructure surface. The sum of the widths of the liquid supply channels 2 and the microcolumn units 3 is 1000 μm, and the width of the liquid supply channels ranges from 100 to 400 μm. The liquid supply channels 2 serve as the macroscopic liquid supply channel of the sidewall-coupled microtubule-enhanced boiling performance composite microstructure surface, ensuring smooth liquid supply to each microcolumn unit 3.

[0029] See also Figure 2 The micropillar units 3 of the composite microstructure surface with sidewall-coupled microtubes for enhanced boiling performance of the present invention are composed of an array of micropillars 4. Microtubes 5 are located on the sidewalls of the micropillars 4 and extend upward through the top surface of the micropillars 4. The gaps between adjacent micropillars 4 are formed by channels 6. On the top surface of the micropillars 4, the microtubes 5 are evenly spaced along the edges of the top surface of the micropillars 4, and the spacing between adjacent microtubes is the same. The microtubes 5 are symmetrically distributed on the top surface of the micropillars 4, distributed in the upper half of the micropillars 4 and extending to the top surface. The length of the microtubes 5 is half the height of the micropillars 4. The micropillars 4 are square pillars with a width of 60-80 μm and a height of 100-140 μm. The width of the channels 6 is 20-40 μm. The microtubes 5 provide more space for boiling to occur and serve as capillary channels for their own fluid replenishment. The channels 6 serve as microscopic fluid replenishment channels for the micropillar units 3, ensuring that fresh fluid is smoothly replenished to each microtube 5.

[0030] See also Figure 3 and Figure 4 The sidewall surfaces of the microcolumns 4 on the surface of the composite microstructure with sidewall-coupled microtubes for enhancing boiling performance of the present invention are inclined surfaces, and the angle A between the sidewall surfaces of the microcolumns 4 and the top surface is 88.8 degrees to 89.2 degrees. The microtubes 5 are circular tubes with a diameter of 3 to 5 μm.

[0031] The technical solutions of the present invention are further described below through examples. It is obvious that the examples described herein are only a portion of the embodiments of the present invention and are not intended to be exhaustive. Based on the embodiments of the present invention, all other embodiments derived by persons of ordinary skill in the art without inventive effort are considered within the scope of protection of the present invention.

[0032] Example 1

[0033] Objective: To prepare a composite microstructure surface with enhanced boiling performance of sidewall-coupled microtubes, which has a microcolumn width of 70 μm, a microcolumn height of 120 μm, a groove of 20 μm, a microtube diameter of 4 μm, a microtube length of 60 μm, a microtube spacing of 14 μm, and 16 microtubes. The microcolumns are distributed in an 8×8 array, the liquid feed channel is 300 μm wide, and the microcolumn units are distributed in a 10×10 array.

[0034] Firstly, a corresponding mask pattern is designed according to the structural characteristics and structural dimensions of the surface of the composite microstructure with sidewall-coupled microtubes for enhanced boiling performance, and then the mask is processed according to the designed mask dimensions.

[0035] The silicon wafer was then pretreated with hexamethyldisilazane (HMDS) for 10 minutes. The pretreated wafer was placed on a spin coater and rotated forward at 600 rpm for 6 seconds, followed by a reverse rotation at 4000 rpm for 30 seconds. This uniformly coated the front surface of the wafer with AZ6130 photoresist to a thickness of 7.5 μm. The wafer was then dried on a contact hot plate at 100°C for 5 minutes to obtain a relatively solid photoresist layer. The wafer was then exposed on an MA6 lithography machine for 23 seconds and developed in a 2.38% tetramethylammonium hydroxide (TMAH) developer for 150 seconds.

[0036] After the development process is complete, a hardening bake is performed at 110°C for 5 minutes. After this 5-minute hardening bake, the etching process begins. During the etching process, the etching process begins with a 5-minute etching process, and the etching rate is measured using a step profiler, which shows a rate of 6μm per minute. An additional 16 minutes of etching is then performed. After microscopic inspection reveals no obvious defects, the resist is removed and the process is complete.

[0037] Figure 5 The following is an oblique scanning electron microscope image of the sidewall-coupled microtube boiling-enhanced composite microstructure surface prepared in Example 1. It can be seen that the novel composite microstructure surface designed in the present invention is structurally stable and has excellent processing quality, which is conducive to large-scale commercial applications. Furthermore, experimental measurements show that the critical heat flux density and boiling heat transfer coefficient of the sidewall-coupled microtube boiling-enhanced composite microstructure surface of this embodiment are improved compared to conventional microstructure surfaces of the same size, as shown in Figure 1. Figure 6 .

[0038] Example 2

[0039] Objective: To prepare a composite microstructure surface with enhanced boiling performance of sidewall-coupled microtubes, which has a microcolumn width of 60 μm, a microcolumn height of 100 μm, a groove of 30 μm, a microtube diameter of 3 μm, a microtube length of 50 μm, a microtube spacing of 12 μm, and 16 microtubes. The microcolumns are distributed in an 8×8 array, the liquid feed channel is 310 μm wide, and the microcolumn units are distributed in a 10×10 array.

[0040] Firstly, a corresponding mask pattern is designed according to the structural characteristics and structural dimensions of the surface of the composite microstructure with sidewall-coupled microtubes for enhanced boiling performance, and then the mask is processed according to the designed mask dimensions.

[0041] The silicon wafer was then pretreated with hexamethyldisilazane (HMDS) for 10 minutes. The pretreated wafer was placed on a spin coater and rotated forward at 600 rpm for 6 seconds, followed by a reverse rotation at 1000 rpm for 30 seconds. This uniformly coated the front surface of the wafer with AZ6130 photoresist to a thickness of 5.2 μm. The wafer was then dried on a contact hot plate at 100°C for 5 minutes to obtain a relatively solid photoresist layer. The wafer was then exposed on an MA6 lithography machine for 23 seconds and developed in a 2.38% tetramethylammonium hydroxide (TMAH) developer for 150 seconds.

[0042] After the development process is complete, a hard film bake is performed at a temperature of 110°C for 5 minutes. After this 5-minute hard film bake, the etching process begins. During the etching process, the etching process is first performed for 5 minutes, and the etching rate is tested using a step profiler, which is 6μm per minute. An additional 10 minutes of etching is then performed. After microscopic inspection shows no obvious defects, the resist is removed and the process is complete.

Claims

1. A composite microstructure surface with sidewall-coupled microtubes for enhanced boiling performance, characterized by: The invention comprises a microcolumn base (1) and a plurality of microcolumn units (3) distributed in an array on the microcolumn base (1), wherein the gaps between adjacent microcolumn units (3) constitute a liquid feeding channel (2) of a composite microstructure surface with sidewall coupling microtubes for enhancing boiling performance; The microcolumn unit (3) is composed of a plurality of microcolumns (4) distributed in an array, the gaps between adjacent microcolumns (4) are grooves (6), and the grooves (6) have the same width; microtubes (5) extending to and penetrating the top surface of the microcolumn (4) are symmetrically opened on each side wall surface of each microcolumn (4), and the microtubes (5) on each side wall surface of each microcolumn (4) are distributed at equal intervals.

2. The sidewall-coupled microtube-enhanced boiling performance composite microstructure surface according to claim 1, characterized in that: The microtubes (5) are distributed in the upper half of each microcolumn (4) and extend through the top surface of the microcolumn (4). The length of the microtubes (5) is half the height of the microcolumn (4).

3. The sidewall-coupled microtube-enhanced boiling performance composite microstructure surface according to claim 2, characterized in that: The microcolumns (4) are square columns with a width of 60 to 80 μm and a height of 100 to 140 μm.

4. The sidewall-coupled microtube-enhanced boiling performance composite microstructure surface according to claim 2, characterized in that: Each side wall surface of the microcolumn (4) is an inclined surface, and the angle A between each side wall surface of the microcolumn (4) and the top surface is the same, and the angle A is 88.8 degrees to 89.2 degrees.

5. The sidewall-coupled microtube-enhanced boiling performance composite microstructure surface according to claim 3 or 4, characterized in that: The microtube (5) is a circular tube with a diameter of 3 to 5 μm.

6. The sidewall-coupled microtube-enhanced boiling performance composite microstructure surface according to claim 5, characterized in that: The sum of the width of the liquid supply channel (2) and the width of the adjacent microcolumn unit (3) on one side is 1000 μm, and the width of the liquid supply channel (2) is 100-400 μm.

7. The sidewall-coupled microtube-enhanced boiling performance composite microstructure surface according to claim 5, characterized in that: The width of the internal channel (6) of the microcolumn unit (3) is 20 to 40 μm.

Images