CN107172859A - A kind of MCA - Google Patents

Abstract

The invention discloses a microchannel structure, comprising a substrate and a microfluidic channel arranged on the substrate, the microfluidic channel includes a main channel and a secondary channel; the main channel is a mesh structure with uniform mesh; the main channel Secondary channels are arranged inside the mesh. Beneficial effects of the present invention: by embedding a spider-like sub-channel in the mesh of the main channel, the deficiency of the existing micro-channel structure in terms of heat dissipation effect is solved. The flow performance in the medium is good, which can improve the comprehensive heat dissipation performance of the micro-channel heat sink.

Description

A microchannel structure

technical field

The invention belongs to the field of heat dissipation of electronic equipment, and in particular relates to a microchannel structure for cooling a large-scale heat source.

Background technique

Since people began to study the cooling of transformers in 1925, thermal design, as one of the realization technologies, has been continuously developed along with the progress of power electronics technology, from vacuum tubes, traveling wave tubes to transistors, from mobile phones, servers to supercomputers, design manufacturers All of them face the cooling problem of their products, but the cooling requirements of each system are different, and the difficulty of thermal design is different. Studies have shown that since the temperature rise exceeding the accommodation limit of electronic equipment is the main factor leading to its failure, when designing electronic equipment, good heat dissipation performance is not only conducive to improving its telecommunication performance and reliability, but also controlling equipment cost and reducing noise , Reduce extra energy consumption. Therefore, efficient cooling of electronic equipment is a key task to maintain stable and reliable operation of various functional modules and large electronic equipment systems.

At present, the heat dissipation technology of electronic equipment mostly adopts natural air cooling or forced air cooling. Generally speaking, natural air cooling has the advantages of simple thermal control components, low cost, low implementation difficulty, and easy improvement, but it will increase the volume and weight of the electronic equipment system, be sensitive to the external environment, and have poor heat dissipation efficiency; forced air cooling is A heat dissipation method that is easy to operate and has obvious effects, and has a stronger heat dissipation capacity than natural air cooling. However, with the continuous development of electronic equipment towards high power consumption and high heat flux density, these traditional cooling methods can no longer meet their heat dissipation requirements.

The emergence of micro-channel cooling technology provides a new solution for the effective thermal control of electronic equipment. Its heat dissipation performance is excellent, it is convenient for high-level integration, and it can quickly and efficiently remove the heat generated by the heating module. With the development trend of assembly density, micro-channel cooling technology has been vigorously promoted and developed.

Since the pioneering research of micro-channel heat dissipation technology by Tucherman et al., with the continuous progress of microfabrication technology, the engineering application of micro-channel heat dissipation technology has become possible. Due to the small cross-sectional area of the micro-channel, the channel is easy to be blocked, so the micro-channel is usually designed as a straight structure with multiple straight channels connected in parallel. Blockage, limited cooling capacity, poor temperature uniformity, etc.

In order to explore the microchannel structure with better comprehensive heat dissipation performance, Pence et al. analyzed the heat transfer performance of the fractal structure thermal surface, Chen et al. analyzed the heat dissipation characteristics of a T-shaped tree-like fractal network structure, Bothe et al. studied the T-shaped and The enhancement effect of Y-shaped flow channel on fluid mixing, Zhou Jianhui et al. proposed a parametric design method and flow field analysis program for Sunflower radiators, Dong Tao et al. proposed a honeycomb microchannel structure based on bionics, and analyzed its flow and heat transfer performance were analyzed. It can be seen that studying the optimal design of microchannel topology has obvious engineering significance to improve the heat dissipation performance of electronic equipment, and has become the main means of thermal design of electronic equipment with high power consumption and high heat flux.

In nature, in order to better adapt to the environment, many biological and non-biological systems have evolved various optimal or near-optimal microtubule fractal networks, such as plant leaf veins, river networks, honeycomb structures, tracheal networks, and spider web structures. Wait. Compared with typical parallel channels, these split networks can not only improve the heat exchange efficiency, but also reduce the energy loss in fluid flow. It can be predicted that the application of bionics in the topology design of microchannels will achieve greater benefits.

Contents of the invention

The technical problem to be solved by the present invention is to provide a microchannel structure with strong heat dissipation capability, good temperature uniformity, good flow performance of cooling working medium in the channel, and can improve the comprehensive heat dissipation performance of the microchannel radiator.

In order to solve the above problems, the technical solution of the present invention is that a microchannel structure includes a substrate and a microfluidic channel arranged on the substrate, and the microfluidic channel includes a main channel and a secondary channel; the main channel is a uniform mesh The network structure; the mesh inside the main channel is arranged with secondary channels. The main channel serves as the skeleton of the entire microfluidic channel structure, so that the cooling working fluid is distributed to each secondary channel through a uniform network structure of mesh holes. A large number of bifurcated structures in the network structure make the fluid flow mode and direction constantly change, which can constantly disturb the boundary layer and prevent it from continuously thickening, thereby enhancing heat transfer. At the same time, the numerous diversion and confluence structures formed by the main channel and the auxiliary channel can play the role of redistribution of cooling working fluid flow and fluid mixing, which can further improve temperature uniformity. In addition, by arranging the auxiliary channel inside the mesh of the main channel, the convective heat transfer area can be further increased, and its heat dissipation capability can be enhanced.

Further, the mesh shapes of the main channels are all regular hexagons, and when covering the same heat dissipation area, the regular hexagons have the shortest perimeter, so that the flow of the mesh structure is shorter and the flow dead zone is less. It can reduce the flow resistance of cooling working fluid. At the same time, the main channels have good distribution uniformity, which can evenly and densely cover the entire area to be dissipated, which not only increases the specific surface area of heat exchange, but also avoids the local heat island phenomenon, and the temperature uniformity is good.

Furthermore, by adjusting the fractal series of the main channel fractal network and the size of the regular hexagonal mesh, the overall temperature rise of the heating surface can be adjusted to meet different heat dissipation requirements.

Further, the secondary channel includes a diagonal secondary channel and an equally divided secondary channel; the diagonal secondary channel communicates with the diagonal points of the main channel mesh, and the equally divided secondary channel communicates with the equally divided points on the diagonal secondary channel ; The diagonal sub-channels and equal sub-channels form a spider web structure, the structure is compact, the heat dissipation specific surface area is large, and the fluid flow performance is good, and the liquid-cooled working medium is interfered by the internal ribs of the channel, so that the flow is always in the development stage , heat transfer efficiency is improved.

Furthermore, the spider web-shaped secondary channel makes the micro-channel cold plate have better mechanical properties, ensuring the normal and stable operation of the thermal control cold plate. When the heat source is unevenly distributed, the temperature uniformity of the area to be dissipated can be improved by embedding spider web-like sub-channels of different levels and sizes in the main channel at different positions in the area to be dissipated.

Furthermore, the shape of the main channel and the auxiliary channel fit perfectly, and the cooling fluid flows smoothly in the flow channel, which can avoid excessive local energy loss and reduce the pressure drop at the inlet and outlet of the micro-channel radiator.

Further, the cross-sectional shapes of the microfluidic channels are all rectangular.

Further, the substrate is made of silicon-based material or metal alloy material (such as aluminum alloy, copper alloy, nickel-based alloy, etc.) with high thermal conductivity.

Further, the base thickness is 1.5 mm.

Further, the main channel has a width of 0.4 mm and a channel height of 0.8 mm, and the secondary channel has a width of 0.2 mm and a channel height of 0.8 mm.

Further, deionized water, FC-75, Coolanol45, Freon, methanol, ethanol, ethylene glycol or an aqueous solution of ethylene glycol can be selected as the cooling medium of the microfluidic channel.

Beneficial effects of the present invention: by embedding a spider-like sub-channel in the mesh of the main channel, the deficiency of the existing micro-channel structure in terms of heat dissipation effect is solved. The flow performance in the medium is good, which can improve the comprehensive heat dissipation performance of the micro-channel heat sink.

Description of drawings

Figure 1 is the main channel network structure, in which (a) regular hexagonal base shape, (b) two-layer structure, (c) three-layer structure, (d) six-layer structure;

Fig. 2 is the subchannel network structure, wherein (a) base shape, (b) two-layer structure, (c) four-layer structure (d) eight-layer structure;

Fig. 3 is the local flow path structure of the microchannel;

Figure 4 is a schematic diagram of the microchannel structure.

detailed description

The present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1-4, a kind of microchannel structure comprises substrate 1 and the microfluidic channel 2 that is arranged on the substrate, and described microfluidic channel 2 comprises main channel 3 and secondary channel 4; Described main channel 3 is a network A mesh structure with uniform holes, the mesh is a regular hexagonal annular flow channel 5, and many regular hexagonal annular flow channels 5 form many shunt structures 6 and confluence structures 7 at the intersections and separations, and the branch channels 8 have the same length , so that the main channel 3 forms a "honeycomb" structure, and the main channel 3 serves as the skeleton of the entire microfluidic channel structure, so that the cooling working fluid is distributed to each of the secondary channels 4 through a uniform mesh structure.

Numerous regular hexagonal annular flow channels 5 make the liquid-cooled working fluid continuously flow through the flow-dividing structure 6 and the converging structure 7, so that the flow mode and direction of the fluid are constantly changing, which can continuously disturb the boundary layer and prevent the boundary layer from continuously thickening, thereby Enhance heat transfer. The regular hexagonal annular flow channels 5 evenly and densely cover the entire area to be dissipated, and are symmetrically distributed in the center, so that the flow of the network structure is shorter, the flow dead zone is less, and the flow resistance of the cooling working medium can be reduced. At the same time, the liquid cooling pipes in the main channel 3 have good distribution uniformity, and can evenly and densely cover the entire area to be dissipated, which not only increases the heat transfer specific surface area, but also avoids the local heat island phenomenon, and the temperature uniformity is good. The preferred cross-sectional shape of the main channel 3 is rectangular, with a channel width of 0.4 mm and a height of 0.8 mm.

As shown in Fig. 2 and Fig. 4, secondary channel 4 includes diagonal secondary channel 10 and equalized secondary channel 9; Channel 9 connects the equal points on the diagonal auxiliary channel 10 to form a multi-level nested regular hexagonal annular flow channel, and makes the auxiliary channel 4 form a spider web structure, which can further increase the convective heat transfer area and strengthen The heat dissipation capacity of the microchannel heat sink. At the same time, different levels and different scales of spider web-like sub-channels 4 can be partially embedded in the "honeycomb"-shaped main channel 3 according to different heat dissipation requirements, so as to improve the temperature uniformity of the area to be radiated. The preferred cross-sectional shape of the secondary channels 4 is rectangular, with a channel width of 0.2 mm and a height of 0.8 mm.

The spider-web-shaped sub-channel 4 has a compact structure, a large heat dissipation specific surface area, and good fluid flow performance, and the liquid-cooled working medium is interfered by the internal ribs of the channel, so that the flow is always in the development stage and the heat exchange efficiency is improved. The substrate 1 is made of silicon-based material or metal alloy material (such as aluminum alloy, copper alloy, nickel-based alloy, etc.) with high thermal conductivity, and the thickness is 1.5 mm. The cooling medium can be deionized water, FC-75, Coolanol45, Freon, methanol, ethanol, ethylene glycol or an aqueous solution of ethylene glycol.

The microfluidic channel 2 can be processed on a silicon-based material substrate by photolithography or deep reactive ion etching technology; or processed on a metal substrate by micro-milling or micro-electric discharge technology; or aluminum-magnesium alloy and nickel The base alloy material is integrally processed and formed.

Experimental example

In order to verify the superior performance of the microchannel structure provided by the present invention in terms of heat dissipation, the traditional rectangular flat microchannel structure and the ordinary imitation honeycomb microchannel structure are used as benchmarks to conduct thermal simulation comparison and analysis of the three microchannel structures. According to the principle of equal parameters, the following settings are specially made: the cold plate material and size are the same; the channel size is the same, and the cross-section is rectangular; the thickness of the substrate is the same; the cooling medium is the same; the thermal load is the same;

Based on this, the detailed thermal simulation calculation model parameters and boundary condition parameters are set as follows:

1. The size of the microchannel cold plate is: 46mm×40mm×4.5mm

2. Cold plate material: aluminum alloy

3. Microchannel cross-sectional size: 0.4mm×1.5mm

4. Substrate thickness: 1.5mm

5. Cooling medium: water

6. Inlet temperature: 25°C

7. Ambient temperature: 25°C

8. Chip power: 400W

9. The convective heat transfer coefficient between the radiator and the surrounding air is: 20W/m ² .K

The thermal simulation models of three microchannel radiators were established, and the same discrete format and solution model were used to perform thermal simulation calculations for the three microchannel radiator structures under different inlet flow rates. The simulation results are shown in the table below.

From the analysis of the above numerical simulation results, it can be concluded that the microchannel structure designed in the present invention can more effectively control the temperature rise of the heating surface and have good temperature consistency.

Those skilled in the art will appreciate that the embodiments described here are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (10)

1. A microchannel structure, characterized in that: comprise a substrate and a microfluidic channel arranged on the substrate, the microfluidic channel comprises a main channel and a secondary channel; the main channel is a uniform mesh structure; the main channel A secondary channel is arranged inside the mesh of the channel. 2. The microchannel structure according to claim 1, characterized in that: the mesh shape of the main channel is a regular hexagon. 3. microchannel structure according to claim 1 and 2, is characterized in that: described secondary channel comprises diagonal secondary channel and equally divided secondary channel; Described diagonal secondary channel communicates with the diagonal point of main channel mesh, The bisecting sub-channels communicate with the bisecting points on the diagonal sub-channels. 4. The microchannel structure according to claim 1, characterized in that: the cross-sectional shapes of the microfluidic channels are all rectangular. 5 . The microchannel structure according to claim 1 , wherein the substrate is made of silicon-based material or metal alloy material with high thermal conductivity. 6. The microchannel structure according to claim 1 or 5, characterized in that: the thickness of the substrate is 1.5 mm. 7. The microchannel structure according to claim 1, characterized in that: the main channel has a width of 0.4 mm and a channel height of 0.8 mm. 8. The microchannel structure according to claim 1, characterized in that: the secondary channel has a width of 0.2mm and a channel height of 0.8mm. 9. The microchannel structure according to claim 1, characterized in that: the cooling medium of the microfluidic channel can be deionized water, FC-75, Coolanol45, Freon, methanol, ethanol, ethylene glycol or ethylene glycol Alcohol in water. 10. The microchannel structure according to claim 5, characterized in that: the metal alloy material is aluminum alloy or copper alloy or nickel-based alloy.