Composite micro-channel structure with wavy channels and staggered trapezoidal fins and application of composite micro-channel structure

Abstract

The invention relates to a composite micro-channel structure with wavy channels and staggered trapezoidal fins and application of the composite micro-channel structure. The composite micro-channel structure comprises an asymmetrical wave-shaped main channel and a plurality of trapezoidal fins arranged in the asymmetrical wave-shaped main channel in a staggered manner; the asymmetric wavy main channel extends in a continuous wavy shape in the flowing direction and comprises a plurality of continuous and repeated flow channel units. The curvature radius of the asymmetric wavy main channel at the wave crest is smaller than the curvature radius of the asymmetric wavy main channel at the wave trough; and the trapezoidal fins are periodically and obliquely distributed at wave crests and wave troughs of the asymmetric wavy main channel to induce fluid to form a Z-shaped flowing path in the channel. Compared with the prior art, the composite micro-channel structure disclosed by the invention can remarkably improve the mixing efficiency and the heat transfer performance of micro-scale fluid under the condition that external energy input is not needed through collaborative optimization of geometrical morphology and fluid dynamics.

Description

Technical Field

[0001] The present invention relates to the technical field of microfluidic devices, and in particular to a composite microchannel structure with wavy channels and staggered trapezoidal ribs and its application. Background Art

[0002] Microchannel technology, a core component of microfluidic systems, is typically characterized by channel dimensions ranging from 10 to 1000 microns. This miniaturized structure, thanks to its large surface area, enables efficient mass and heat transfer, and is widely used in applications requiring enhanced mass and heat transfer, such as microreactor chip heat sinks and fuel cells. However, traditional microchannel technology still faces numerous bottlenecks. For example, conventional straight-channel structures lack effective fluid perturbation mechanisms and rely primarily on molecular diffusion for mixing, resulting in low reaction or heat transfer efficiency and making it difficult to meet the demands of high-precision, fast-response applications.

[0003] To address these issues, existing technologies have introduced serpentine or wavy channel designs, which enhance mixing and heat transfer by inducing secondary flows through curved channels. For example, CN115845761A discloses a microchannel reaction plate with multiple wavy main flow channels within its main flow channel area. However, such symmetrically curved channels often result in significant pressure drop due to flow separation, and the secondary flow vortex intensity rapidly decreases with extended flow, limiting overall performance improvements.

[0004] In addition, some improvements have increased the heat transfer area by installing parallel fin structures within the channel. However, a single fin layout can easily lead to flow dead zones, which not only reduces the utilization of the effective heat transfer area but can also cause flow instability and produce uncontrollable turbulent disturbances at high Reynolds numbers. These factors make it difficult for existing microchannel structures to achieve an effective balance between mixing efficiency, heat transfer performance, flow stability, and machinability, restricting their further application in advanced fields such as microreactors and high-power electronic cooling.

[0005] Therefore, the mixing uniformity and heat transfer efficiency of the existing microchannel structure still need to be improved, and a new composite microchannel structure that can be used in miniaturized devices still needs to be developed. Summary of the Invention

[0006] The purpose of the present invention is to provide a composite microchannel structure and application with wavy channels and staggered trapezoidal fins in order to overcome the defects of existing microchannel structures in terms of mixing uniformity and heat transfer efficiency.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention first provides a composite microchannel structure having a wavy channel and staggered trapezoidal fins, wherein the composite microchannel structure comprises an asymmetric wavy main channel and a plurality of trapezoidal fins staggered in the asymmetric wavy main channel;

[0009] The asymmetric wavy main channel extends in a continuous wavy shape along the flow direction, and includes a plurality of continuously repeated flow channel units; the curvature radius of the asymmetric wavy main channel at the wave crest is smaller than the curvature radius at the wave trough;

[0010] The trapezoidal fins are periodically and obliquely distributed at the crests and troughs of the asymmetric wavy main channel, inducing the fluid to form a Z-shaped flow path in the channel.

[0011] Furthermore, the cross section of the asymmetric wavy main channel is a hollow rectangular cross section, and the cross section shape of the asymmetric wavy main channel remains constant along its extension direction.

[0012] Furthermore, the length of the long side of the hollow rectangular cross section is 1-1.5 mm, preferably 1.2 mm; the length of the short side is 0.6-1 mm, preferably 0.8 mm.

[0013] Furthermore, the wall thickness of the asymmetric wavy main channel is 0.1-0.5 mm, preferably 0.3 mm.

[0014] Furthermore, the ratio of the wavelength to the wave height of the flow channel unit is (1.3-1.7):1, preferably 1.5:1.

[0015] Furthermore, the wavelength of the flow channel unit is 18-22 mm, preferably 20 mm.

[0016] Furthermore, the wave height of the flow channel unit is 14-16 mm, preferably 15 mm.

[0017] Furthermore, the curvature radius of the asymmetric wavy main channel at the wave crest is 0.4-0.6 mm, preferably 0.5 mm.

[0018] Furthermore, the curvature radius of the asymmetric wavy main channel at the trough is 2.5-3.5 mm, preferably 3 mm.

[0019] Furthermore, the height of the trapezoidal fins is 40%-60%, preferably 50%, of the height of the cross section of the asymmetric wavy main channel.

[0020] Furthermore, the trapezoidal rib is an isosceles trapezoidal structure, the bottom side width is greater than the top side width, and the bottom wall of the trapezoidal rib smoothly transitions to the bottom surface of the asymmetric wavy main channel.

[0021] Furthermore, connecting transverse branches are provided between the asymmetric wavy main channels on both sides of the wave crest, so that the flow unit is A-shaped as a whole.

[0022] Furthermore, the transverse branches are all located at the same height in the flow direction of the asymmetric wavy main channel.

[0023] Furthermore, the distance from the transverse branch to the wave crest accounts for 45-55% of the total length of the wave height of the flow channel unit, preferably 50%.

[0024] Furthermore, the height of the transverse branch is 1.1-1.3 mm, preferably 1.2 mm.

[0025] The present invention also provides an application of a composite microchannel structure in microreactors, chip radiators, and fuel cells, which specifically shows excellent engineering application potential in the fields of microchemical reactions, high-density electronic heat dissipation, and thermal management of new energy devices.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The composite microchannel structure of the present invention integrates an asymmetric wavy main channel and trapezoidal fins. Through the coordinated optimization of geometric morphology and fluid dynamics, it can effectively stimulate high-intensity secondary vortices and guide the reorganization of the three-dimensional spatial flow field, which can significantly improve the mixing efficiency and heat transfer performance of microscale fluids without the need for external energy input.

[0028] (2) The optimized matching of the gradual curvature of the flow channel and the trapezoidal cross-section of the fins enhances flow disturbance while suppressing flow separation, thereby achieving low flow resistance and high stability in a wide range of flow control.

[0029] (3) The present invention can selectively add a transverse branch unit to periodically divert part of the fluid at the wave crest. The jet impact and the main channel backflow interact to generate multi-scale disturbances to further destroy the boundary layer and enhance material mixing, thereby improving mass transfer / heat transfer efficiency.

[0030] (4) The composite microchannel structure of the present invention has both geometric simplicity and process adaptability, and can adapt to various processing methods such as micro-milling and etching. It shows excellent engineering application potential in the fields of micro-chemical reactions, high-density electronic heat dissipation and thermal management of new energy devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the composite microchannel junction of the present invention.

[0032] Figure 2 Schematic diagram of the three-dimensional structure of the composite microchannel junction of the present invention.

[0033] Figure 3 This is a cross-sectional view of the asymmetric wavy main channel in Example 2 of the present invention.

[0034] Figure 4 This is a schematic structural diagram of a flow channel unit in Example 2 of the present invention.

[0035] Figure 5 This is a schematic structural diagram of the trapezoidal fins in Example 2 of the present invention.

[0036] Description of the marks in the figure:

[0037] 1-asymmetric wavy main channel, 11-peak, 12-trough;

[0038] 2-trapezoidal ribs;

[0039] 3- lateral branches. DETAILED DESCRIPTION

[0040] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0041] In the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes and should not be understood as indicating or implying relative importance; in addition, unless otherwise expressly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or it can be internal communication between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0043] Example 1:

[0044] This embodiment provides a composite microchannel structure with wavy channels and staggered trapezoidal fins, such as Figure 1-2As shown, the composite microchannel structure includes an asymmetric wavy main channel 1 and a plurality of trapezoidal fins 2 staggeredly arranged in the asymmetric wavy main channel 1.

[0045] The asymmetric wavy main channel 1 of this embodiment extends in a continuous wavy pattern along the flow direction and comprises multiple, repeating flow channel units. The asymmetric wavy main channel 1 employs a differentiated curvature design, with the radius of curvature at crests 11 being smaller than that at troughs 12. This stimulates stable secondary vortices within the fluid through the coupling of an unbalanced centrifugal force field and a pressure gradient.

[0046] The trapezoidal fins 2 of this embodiment are periodically tilted and distributed at the crests 11 and troughs 12 of the asymmetric wavy main channel 1, inducing the fluid to form a Z-shaped flow path in the channel, and realizing three-dimensional flow field disturbance by cutting, deflecting and reorganizing the mainstream.

[0047] The composite microchannel structure of this embodiment integrates an asymmetric wavy main channel 1 and trapezoidal fins 2. Through the coordinated optimization of geometry and fluid dynamics, it can effectively stimulate high-intensity secondary vortices and guide the reorganization of the three-dimensional spatial flow field, which can significantly improve the mixing efficiency and heat transfer performance of microscale fluids without the need for external energy input.

[0048] Example 2:

[0049] This embodiment provides a composite microchannel structure having a wavy channel and staggered trapezoidal fins. The composite microchannel structure includes an asymmetric wavy main channel 1 and a plurality of trapezoidal fins 2 staggered in the asymmetric wavy main channel 1 .

[0050] The difference from Example 1 is that Figure 3 As shown, the cross-section of the asymmetric wavy main channel 1 of this embodiment is a hollow rectangular cross-section. The cross-sectional shape of the asymmetric wavy main channel 1 remains constant along its extension direction. The long side of the hollow rectangular cross-section is 1.2 mm long, the short side is 0.8 mm long, and the wall thickness of the asymmetric wavy main channel 1 is 0.3 mm.

[0051] like Figure 4 As shown, the wavelength-to-wave height ratio of the flow channel unit in this embodiment is 4:3. The wavelength of the flow channel unit is 20 mm, and the wave height of the flow channel unit is 15 mm. The asymmetric wavy main channel 1 in this embodiment has a curvature radius of 0.5 mm at the crest and 3 mm at the trough, using a differentiated curvature design to form an asymmetric geometric configuration.

[0052] like Figure 5 As shown in FIG. 1 , the height of the trapezoidal fins 2 in this embodiment is 50% of the cross-sectional height of the asymmetric wavy main channel 1. Figure 4As shown, the trapezoidal rib 2 is an isosceles trapezoidal structure, the width of its bottom side is greater than the width of its top side, and the bottom side smoothly transitions to the inner wall of the asymmetric wavy main channel 1.

[0053] Example 3:

[0054] This embodiment provides a composite microchannel structure having a wavy channel and staggered trapezoidal fins. The composite microchannel structure includes an asymmetric wavy main channel 1 and a plurality of trapezoidal fins 2 staggered in the asymmetric wavy main channel 1 .

[0055] This embodiment differs from Example 1 in that transverse branches 3 are added to connect the asymmetric wavy main channel 1 on either side of the wave crest 11, giving the flow unit an A-shape. These transverse branches 3 are located at the same height along the flow direction of the asymmetric wavy main channel 1. The distance from each transverse branch 3 to the wave crest 11 accounts for 50% of the total wave height of the flow channel unit. The height of the transverse branches 3 is 1.2 mm.

[0056] This embodiment adds a transverse branch 3 on the basis of the composite microchannel structure, which can periodically divert part of the fluid at the wave crest. The interaction between the jet impact and the main channel backflow produces multi-scale disturbances, further destroying the boundary layer and enhancing material mixing, so as to further improve the fluid uniformity.

[0057] Example 4:

[0058] This embodiment provides a composite microchannel structure with a wavy channel and staggered trapezoidal fins 2 to achieve efficient mixing and heat transfer of fluids within the microchannel structure. The composite microchannel structure of this embodiment is composed of an asymmetric wavy main channel 1, built-in staggered trapezoidal fins 2, and transverse branches 3.

[0059] like Figure 1-5 As shown, the asymmetric wavy main channel 1 of this embodiment extends in a continuous wavy shape along the flow direction and is composed of a plurality of flow channel units. The crest 11 and trough 12 thereof adopt a differentiated curvature design, with a small curvature radius at the crest and a large curvature radius at the trough, forming an asymmetric geometric configuration. The curvature radius at the crest of this embodiment is 0.5 mm, and the curvature radius at the trough is 3 mm. By coupling the unbalanced centrifugal force field with the pressure gradient, a stable secondary vortex is excited in the fluid. The cross-section of the asymmetric wavy main channel 1 of this embodiment is a constant rectangular cross-section, the long side length of the hollow rectangular cross-section is 1.2 mm, the short side length is 0.8 mm, and the wall thickness of the asymmetric wavy main channel 1 is 0.3 mm. The wavelength of the flow channel unit is 20 mm, the wave height is 15 mm, and the ratio of wavelength to wave height is 4:3 to ensure flow stability. The crest 11 and the trough 12 are connected by a gradual curvature to avoid flow separation and sudden changes in pressure drop.

[0060] The inner wall of the asymmetric wavy main channel 1 of this embodiment is periodically arranged with trapezoidal fins 2. The trapezoidal fins are staggered in the wave crest 11 and wave trough 12 areas to form a "Z"-shaped guide path, which realizes three-dimensional flow field disturbance by cutting, deflecting and reorganizing the mainstream. The cross-section of the trapezoidal fins 2 of this embodiment is an isosceles trapezoid, the bottom side is wider than the top side, and the bottom wall of the trapezoidal fins 2 transitions smoothly with the bottom surface of the channel. The height of the trapezoidal fins 2 is 50% of the channel height. The isosceles trapezoidal cross-section design of the trapezoidal fins 2 combined with the gradual curvature characteristics of the wavy flow channel can effectively suppress the flow dead zone and reduce pressure loss.

[0061] In this embodiment, the transverse branches 3 periodically divert some fluid at crests 11. The interaction between the jet impact and the main channel backflow generates multi-scale disturbances, further disrupting the boundary layer and enhancing material mixing. This periodic diversion and confluence induces multi-scale vortices and enhances the wall scouring effect.

[0062] The working principle of the composite microchannel structure of this embodiment is:

[0063] After entering the asymmetric wavy main channel 1, the fluid moves along the axis of the wave crests 11 and troughs 12, which have a gradually changing curvature. The shallow curvature on the upstream side induces a strong centrifugal force, deflecting the fluid outward. The large curvature area on the downstream side creates a reverse pressure gradient. These two forces, coupled together, drive the near-wall fluid back toward the center, generating a continuous secondary vortex. Simultaneously, the staggered trapezoidal fins 2 cut the main flow at an oblique angle, forcing the fluid to split and deflect, forming a "Z"-shaped return path between adjacent fins. Combined with the rotational action of the secondary vortex, this achieves three-dimensional stretching, folding, and diffusion of the fluid. The lateral branch units 3 periodically divert part of the fluid at the wave crests 11. The interaction between the jet impact and the main channel return flow generates multi-scale disturbances, further disrupting the boundary layer and enhancing material mixing. The entire process, through the synergistic disturbance of the asymmetric wavy main channel 1 geometry and the internal structure, achieves efficient heat transfer and rapid mixing under low flow resistance conditions. Ultimately, the cumulative effect of the successive wave units outputs a homogenized fluid, or achieves efficient heat and mass exchange.

[0064] The simulation process of heat and mass transfer performance of the composite microchannel structure of this embodiment and the traditional rectangular cross-section straight tube microchannel is as follows:

[0065] (1) Basic parameters

[0066] Assuming the working fluid is water at room temperature and the flow rate is 0.1m / s, the kinematic viscosity is 1×10 -6 m 2 / s.

[0067] Hydraulic diameter: D = 4A / P = (4 × 1.2 × 0.8) / (1.2 + 1.2 + 0.8 + 0.8) = 0.96 mm;

[0068] Reynolds number: Re = UD / ν = 0.1 × 0.00096 / 10 -6 =96;

[0069] Molecular diffusion coefficient: D′=1×10 -9 m 2 / s (typical diffusion coefficient);

[0070] Schmidt number: Sc = ν / D′ = 10 -6 / 10 -9 =1000;

[0071] Dean number:

[0072] Fin surface ratio: η rib =10%.

[0073] (2) Calculation of thermal efficiency improvement:

[0074] The heat transfer limit of a traditional straight channel, when the laminar flow is fully developed, the theoretical value of the Nusselt number for a rectangular channel is:

[0075] Nu straight =3.66 (constant wall temperature boundary condition);

[0076] The enhanced heat transfer mechanism of this embodiment:

[0077] Secondary flow vortex enhancement (Dean vortex effect):

[0078]

[0079] Fin area gain:

[0080]

[0081] Improved overall heat transfer efficiency:

[0082]

[0083] From the above calculations, it can be seen that the theoretical heat transfer efficiency is improved by 90.3%.

[0084] (3) Calculation of mass transfer efficiency improvement

[0085] The mass transfer limit of traditional straight channels is dominated by laminar diffusion. If the channel length L = 10 cm, the mixing time is: (pure diffusion, convection assistance is required in practical applications);

[0086] Mass transfer enhancement mechanism of this embodiment:

[0087] Streamline folding effect: The zigzag path extends the effective mixing length, and the gain factor is C path =2.2;

[0088] Vortex-enhanced diffusion improves the effective diffusion coefficient:

[0089]

[0090] Mixing time shortened by:

[0091] Calculation of percentage reduction in mixing time:

[0092] From the above calculations, it can be seen that the mixing speed is increased by 740 times compared with the traditional straight tube, and the mixing time is reduced by 98.86%.

[0093] In summary, the composite microchannel structure of the present invention can significantly improve the mixing efficiency and heat transfer performance of microscale fluids through the coordinated optimization of geometry and fluid dynamics without the need for external energy input. At the same time, it has high Reynolds number adaptability and process compatibility, and can be widely used in microreactors, high-power electronic liquid cooling, fuel cell gas distribution and other fields.

[0094] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A composite microchannel structure having a wavy channel and staggered trapezoidal fins, characterized in that: The composite microchannel structure comprises an asymmetric wavy main channel (1) and a plurality of trapezoidal fins (2) staggeredly arranged in the asymmetric wavy main channel (1); The asymmetric wavy main channel (1) extends in a continuous wavy shape along the flow direction, and comprises a plurality of continuously repeated flow channel units; the curvature radius of the asymmetric wavy main channel (1) at the wave crest (11) is smaller than the curvature radius at the wave trough (12); The trapezoidal fins (2) are periodically and obliquely distributed at the wave crests (11) and wave troughs (12) of the asymmetric wavy main channel (1), inducing the fluid to form a zigzag flow path in the channel.

2. A composite microchannel structure having a wavy channel and staggered trapezoidal fins according to claim 1, characterized in that: The cross section of the asymmetric wavy main channel (1) is a hollow rectangular cross section, and the cross-sectional shape of the asymmetric wavy main channel (1) remains constant along its extension direction.

3. The composite microchannel structure having a wavy channel and staggered trapezoidal fins according to claim 2, characterized in that: The long side of the hollow rectangular cross section is 1-1.5 mm in length, and the short side is 0.6-1 mm in length; The wall thickness of the asymmetric wavy main channel (1) is 0.1-0.5 mm.

4. The composite microchannel structure having a wavy channel and staggered trapezoidal fins according to claim 1, characterized in that: The ratio of the wavelength to the wave height of the flow channel unit is (1.3-1.7):1; The wavelength of the flow channel unit is 18-22 mm; The wave height of the flow channel unit is 14-16 mm.

5. The composite microchannel structure having a wavy channel and staggered trapezoidal fins according to claim 1, characterized in that: The asymmetric wavy main channel (1) has a curvature radius of 0.4-0.6 mm at the wave crest; The asymmetric wavy main channel (1) has a curvature radius of 2.5-3.5 mm at the trough.

6. The composite microchannel structure having a wavy channel and staggered trapezoidal fins according to claim 1, characterized in that: The height of the trapezoidal ribs (2) is 40%-60% of the cross-sectional height of the asymmetric wavy main channel (1).

7. The composite microchannel structure having a wavy channel and staggered trapezoidal fins according to claim 1, characterized in that: The trapezoidal rib (2) is an isosceles trapezoidal structure, the bottom side width is greater than the top side width, and the bottom wall of the trapezoidal rib (2) smoothly transitions to the bottom surface of the asymmetric wavy main channel (1).

8. The composite microchannel structure having a wavy channel and staggered trapezoidal fins according to claim 1, characterized in that: A communicating transverse branch (3) is provided between the asymmetric wavy main channel (1) on both sides of the wave crest (11), so that the flow unit as a whole presents an A-shape; The transverse branches (3) are all located at the same height in the flow direction of the asymmetric wavy main channel (1).

9. The composite microchannel structure having a wavy channel and staggered trapezoidal fins according to claim 8, characterized in that: The distance from the transverse branch (3) to the wave crest (11) accounts for 45%-55% of the total length of the wave height of the flow channel unit; The height of the transverse branch (3) is 1.1-1.3 mm.

10. Use of the composite microchannel structure according to any one of claims 1 to 9 in a microreactor, a chip heat sink, or a fuel cell.

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