Turbulence-enhanced liquid cooling plate with bent flow channel and production process of turbulence-enhanced liquid cooling plate

Abstract

The invention provides a turbulence-enhanced bent flow channel liquid cooling plate and a production process thereof, and relates to the technical field of heat dissipation of electronic devices. The invention relates to a turbulence-enhanced liquid cooling plate with a bent flow channel. The liquid cooling plate comprises a substrate and a red copper pipe embedded in the substrate, four embedded grooves are formed in the surface of the substrate; the red copper pipe is embedded in the embedded groove, and the copper pipe is continuously bent to form a tandem four-channel flow channel; a plurality of horizontal-downward-lifting bending units are arranged on the straight pipe section of the copper pipe at intervals, and the bending angle of each bending unit is 30 degrees. Cooling liquid is forced to form turbulent flow through sudden change of the flow channel direction, a laminar flow boundary layer is broken, and the convection heat exchange efficiency is remarkably improved; and moreover, no built-in component is needed, the structure is stable, the processing is simple and convenient, and the heat dissipation device is suitable for high-efficiency heat dissipation of high-power electronic devices and battery modules.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation technology for electronic devices, and in particular to a turbulence-enhanced bent flow channel liquid cooling plate and its manufacturing process. Background Technology

[0002] With the rapid development of electronic technology, the integration of high-power electronic devices, small battery modules, and other equipment is constantly increasing, leading to a sharp increase in the heat generated during their operation. If this heat cannot be dissipated in time, the internal temperature of the equipment will rise, seriously affecting its operational stability, reliability, and lifespan. Liquid cooling plates, as a highly efficient heat dissipation component, are widely used in the heat dissipation systems of such equipment.

[0003] In existing technologies, M-type flow channel liquid cooling plates are widely used due to their advantages such as compact flow channel layout and large heat dissipation area. However, traditional M-type flow channel liquid cooling plates mostly use straight tubes and horizontal flow channels, which easily lead to laminar flow of the coolant within the flow channel. In laminar flow, the higher the velocity, the lower the convective heat transfer efficiency between the coolant and the inner wall of the flow channel, making it difficult to meet the high-efficiency heat dissipation requirements of high-power equipment.

[0004] To improve heat exchange efficiency, existing technologies often employ methods such as adding built-in components (e.g., turbulence-inducing columns, spiral blades, etc.) within the flow channel, or CNC machining cylindrical or rectangular features within the flow channel to force turbulence. However, adding built-in components significantly increases flow resistance, leading to increased energy consumption of the heat dissipation system. Furthermore, the installation of built-in components increases the difficulty of machining the liquid cooling plate and the cost of CNC machining, and also poses a risk of flow channel blockage.

[0005] For example, Chinese patent application No. 202010383793.5, entitled "Ultra-low Flow Resistance Microchannel Liquid Cooling Heat Exchange Based on Elastic Turbulence," describes an ultra-low flow resistance microchannel liquid cooling heat exchanger based on elastic turbulence and its manufacturing method. The heat exchanger includes a bonded and sealed heat dissipation base plate and cover plate. The heat dissipation base plate has a working fluid inlet, several periodically curved-variable cross-section microchannels, and a working fluid inlet. The working fluid inlet is located at one end of the heat dissipation base plate, and the working fluid outlet is located at the other end. A liquid distribution zone is connected to the working fluid inlet, and one end of each periodically curved-variable cross-section microchannel is connected to the liquid distribution zone, while the other end is connected to the liquid collection zone. This invention utilizes the synergistic effect of the periodically curved-variable cross-section combined microchannel structure and viscoelastic fluid to generate a significant elastic turbulence effect within the microchannels at low Reynolds numbers, thereby significantly enhancing the heat transfer coefficient at low Reynolds numbers. This invention eliminates the need for adding turbulent micropillars or increasing flow velocity to create turbulence, thus significantly reducing the flow pressure drop and pump power consumption of microchannel heat exchangers under the same heat exchange conditions. However, this invention suffers from drawbacks such as complex manufacturing processes, high costs, and the susceptibility to failure due to copper tube bending.

[0006] Therefore, the core idea of ​​this invention is to develop a liquid cooling plate that can enhance heat exchange efficiency without complex processing or the addition of extra built-in components, while also taking into account low flow resistance and structural stability. This has become a technical problem that urgently needs to be solved in the field. Summary of the Invention

[0007] Therefore, it is necessary to address the problems of existing technologies by providing a turbulence-enhanced bent flow channel liquid cooling plate and its manufacturing process. This liquid cooling plate can enhance heat exchange efficiency without complex processing or the addition of extra built-in components, while also ensuring low flow resistance and structural stability.

[0008] To address the problems in the existing technology, the present invention adopts the following technical solution:

[0009] A turbulence-enhanced bent flow channel liquid cooling plate is characterized by comprising a substrate and a copper tube embedded in the substrate; four embedded grooves are formed on the surface of the substrate; the copper tube is embedded in the embedded grooves, and the copper tube is continuously bent to form a series of four-channel flow channels; the straight section of the copper tube is provided with several sets of "horizontal-downward-lifting" bending units at intervals, and the bending angle of the bending unit is 30°.

[0010] Furthermore, four U-shaped flow channels are formed on the surface of the substrate, creating four embedded grooves.

[0011] Furthermore, the copper tube is continuously bent to form a series M-shaped flow channel.

[0012] Furthermore, the bending units are evenly spaced along the straight section of the copper tube.

[0013] Furthermore, the bending unit is provided in 3 sets.

[0014] Furthermore, the four embedded grooves are arranged in parallel, and the cross-sectional shape of the grooves is adapted to the outer contour of the copper tube.

[0015] Furthermore, the copper tube and the embedded groove are fixed by tight fitting riveting or thermally conductive adhesive bonding.

[0016] Furthermore, the substrate is made of 6061 aluminum alloy and has dimensions of 152mm×127mm×17mm.

[0017] Furthermore, the copper tube has an outer diameter of 9.52 mm, a wall thickness of 1.5 mm, and an inner diameter of 6.52 mm.

[0018] Furthermore, a manufacturing process for a turbulence-enhanced bent flow channel liquid-cooled plate includes the following steps:

[0019] a) Prepare a 6061 aluminum alloy substrate and process four U-shaped embedded grooves using profile technology;

[0020] b) Bend the copper tubes into a series M-type flow channel according to the design requirements, and set 30° bending units in the straight pipe sections;

[0021] c) Embed the bent copper tube into the groove and fix it by riveting or bonding.

[0022] d) Perform airtightness testing and surface treatment.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. High heat transfer efficiency: Turbulent flow enhances convective heat transfer, increasing the heat transfer coefficient by more than 10%;

[0025] 2. Low flow resistance: Resistance increment is controlled within 10%, compatible with existing cooling systems;

[0026] 3. Stable structure: Optimized bending angle to prevent copper tube cracking;

[0027] 4. Simple processing: No built-in components are required, making it suitable for mass production;

[0028] 5. Wide applicability: Can be used in various heat dissipation scenarios such as high-power chips and battery modules. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the liquid cooling plate structure of the present invention;

[0030] Figure 2 This is a schematic diagram of a copper tube bending unit;

[0031] Figure 3 A schematic diagram showing the trench configuration for the substrate;

[0032] Figure 4 This is a comparison chart of temperature distribution in thermal simulation.

[0033] Figure 5 This is a comparison chart of temperature distribution in thermal simulation.

[0034] Figure 6 A comparison chart of simulated flow resistance of liquid in a pipe;

[0035] Figure 7 This is a comparison chart of simulated flow velocities of liquids inside a pipe. Detailed Implementation

[0036] To further understand the features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0037] Labeling explanation: 1. Substrate; 2. Copper tube; 3. Bending unit; 4. Groove;

[0038] A turbulence-enhanced bent flow channel liquid cooling plate includes a substrate 1 and a copper tube 2 embedded in the substrate 1; the substrate 1 is made of 6061 aluminum alloy, which has excellent thermal conductivity and mechanical strength, and is moderately priced, making it suitable for the heat dissipation needs of high-power electronic devices and small battery modules.

[0039] The substrate 1 is set to a size of 152mm×127mm×17mm. This size has been verified through practical application and can well adapt to the installation size requirements of mainstream high-power electronic devices and small battery modules.

[0040] Furthermore, the substrate 1 has four U-shaped flow channels formed on its surface in a 127-dimensional direction using a profile process. This profile process can replace traditional CNC machining to form four embedded grooves 4. The arrangement of these four grooves can maximize the heat dissipation area and improve the heat dissipation uniformity while ensuring the structural strength of the substrate.

[0041] Furthermore, the copper tube 2 is embedded in the embedded groove 4, and the copper tube 2 and the aluminum base plate are tightly bonded together by the pressure of the punch press. Copper has excellent thermal conductivity and is a preferred material for liquid cooling channels; the outer diameter of the copper tube 2 is set to 9.52mm, the wall thickness to 1.5mm, and the inner diameter to 6.52mm. These dimensional parameters, after fluid mechanics and heat transfer analysis, can achieve a reasonable flow rate of coolant and heat exchange effect while ensuring the structural strength of the copper tube.

[0042] Furthermore, the copper tube 2 is continuously bent to form a series M-shaped flow channel. The M-shaped flow channel has a compact layout, which can extend the flow channel length within a limited substrate area, increase the contact time between the coolant and the inner wall of the copper tube, and improve the heat dissipation effect.

[0043] The core improvement of this invention lies in the arrangement of three sets of "horizontal-downward-upward" bending units 3 at intervals along the straight sections of the copper tube. Through extensive theoretical derivation, parameter calculation, and thermal simulation analysis, the bending angle of the bending unit was determined to be 30°. The specific derivation process and formula are as follows:

[0044] I. Design Parameters and Theoretical Basis

[0045] The core of this invention is based on three dimensions: turbulence generation conditions, pipe mechanical properties, and flow resistance constraints. Combining the specific specifications of substrate 1 (152mm×127mm×17mm) and copper pipe 2 (outer diameter 9.52mm, wall thickness 1.5mm, inner diameter d=6.52mm), the optimal range for the bending angle is determined to be 30° through formula derivation.

[0046] 1. Critical conditions for turbulence generation (derivation of local Reynolds number)

[0047] When fluid flows through a bending element, the intensity of the disturbance caused by the abrupt change in the flow direction is characterized by the local Reynolds number Re', as shown in the following formula:

[0048]

[0049] The definition and values ​​of parameters in the formula:

[0050] ρ: Coolant density (based on 25 degrees Celsius and deionized water, value is 998 kg / m3).

[0051] v: Coolant working flow rate (2m / s);

[0052] d: Inner diameter of the copper tube (6.52mm=0.00652m);

[0053] μ: Dynamic viscosity of coolant (deionized water, valued at 0.001 Pa·s at 25 degrees Celsius);

[0054] θ: The downward bending angle of the copper tube (relative to the horizontal clamp);

[0055] Based on the critical condition for the repetitive development of heat transfer turbulence in logistics theory, Re' > 4000 (or equal to 4000), so the following calculation is performed using the parameter formula:

[0056]

[0057] Therefore, our calculations show that the result is the minimum threshold condition for turbulence. From the derivation of the Reynolds formula in fluid mechanics, as long as sinθ≥−0.6952 (corresponding to θ≥43.8°, so theoretically the Reynolds coefficient Re'>4000 is met, the critical point is reached.

[0058] By deriving the formula, when θ≤15°, sin10=0.1736, and thus Re'≈15255≥4000, we can see that the bending angle is too small, resulting in too little disturbance to the fluid and an inability to break the laminar boundary layer.

[0059] Similarly, when θ=25°, sin10=0.4226, we get Re'≈18505≥4000. At this time, the bend can disturb the flow, completely break the laminar boundary layer, and the turbulence enters the development stage, and the heat exchange effect is significantly improved.

[0060] Similarly, when θ = 30°, sin30 = 0.5, so Re' ≈ 19512 ≥ 4000;

[0061] The turbulence intensity was further improved, and the mixing and heat exchange efficiency of the flow reached its optimal level.

[0062] Ultimate limits of mechanical and structural performance of pipes (to prevent bending failure)

[0063] Copper tube 2 is made of T2 copper. The minimum bending radius for the bending process is Rmin = 1.5d = 1.5 x 6.52 = 9.78 mm. Simultaneously, the relationship between the bending angle and the stress on the tube wall satisfies the following:

[0064]

[0065] Parameter definitions and values ​​in the formula:

[0066] E: Elastic modulus of copper (110 GPa = 110 x 10^9 Pa)

[0067] R: Radius of curvature at the bend (take R = 10mm > Rmin)

[0068] σ allow: Allowable stress of copper (≤120 MPa)

[0069] Therefore, substituting θ=30° into the above formula, we get:

[0070]

[0071] The calculated stress is σ = 35860 x 10^6 x 0.2588 = 9.28 MPa. This stress is far below 120 MPa, therefore, there is no risk of pipe cracking.

[0072] Flow resistance constraints (control system energy consumption)

[0073] The formula for the local resistance loss Δp generated by the bending element is:

[0074]

[0075] ζ: Local drag coefficient;

[0076] ρ: Coolant density;

[0077] v: Average flow velocity of the fluid within the flow channel;

[0078] The local resistance coefficient in the formula is related to the bending angle. The values ​​for different angles and the corresponding assistant increments are shown in the table below:

[0079]

[0080] In general engineering projects, the engineering requirements stipulate that the increase in resistance of the entire flow channel should not exceed 20% of that of a straight pipe structure. Therefore, θ needs to be controlled within 30°. At this time, the resistance increase is only 16%, and there is no need to replace the high-lift water pump, which is compatible with the existing water cooling system.

[0081] Therefore, based on the derivation of the above three theoretical formulas, the calculation results show that when the bending angle is defined as 30 degrees, the structural setting of the "horizontal-downward-upward" bending unit 3 can cause severe disturbance to the coolant when it flows through the unit, forcing the formation of turbulence, breaking the limitation of the laminar boundary layer, and significantly enhancing the convective heat transfer efficiency between the coolant and the inner wall of the copper pipe. The mechanical structural performance limit value of the pipe is also optimal, and the flow resistance parameters are also guaranteed to be below the engineering requirements.

[0082] Furthermore, the bending units 3 are evenly distributed along the length of the straight section of the copper tube 2, which can ensure that the coolant is uniformly disturbed throughout the entire flow channel, achieving efficient heat exchange throughout the entire flow channel and avoiding local heat exchange dead zones.

[0083] The four embedded grooves 4 are arranged in parallel, and the cross-sectional shape of the grooves 4 is adapted to the outer contour of the copper tube 2, which can ensure the tight fit between the copper tube and the groove, reduce contact thermal resistance, and improve heat conduction efficiency. At the same time, the parallel grooves are produced by precision profile mold process, which reduces production difficulty and processing cost.

[0084] Furthermore, the copper tube 2 and the embedded groove 4 can be bonded and fixed with thermally conductive adhesive. The thermally conductive adhesive can not only firmly fix the copper tube to the substrate, but also fill the tiny gap between them, further reducing the contact thermal resistance and improving the overall heat dissipation performance.

[0085] 2. Analysis conclusions using Ansys 2022R1 ICPAK thermal simulation software: (see attached) Figure 4-6 Thermal Simulation Analysis Report

[0086] Model the model using 3D software according to the above dimensions of 52mm×127mm×17mm, and save the model as a *.stp file;

[0087] Open the CDM software to extract the flow channels;

[0088] Convert the model into an Icepak computable solid model using Ansys 2022R1 software;

[0089] The operating environment temperature is set to 35 degrees Celsius, the flow rate to 6 L / min, and the thermal power to 1000 W.

[0090] Set the convergence step size to 2000 steps (convergence will automatically stop after 820 steps).

[0091] The flow velocity results from the operation are as follows: the flow velocity of the model with a 30-degree bend "horizontal-downward bend-upward bend" in this invention is 2.86 m / min; the flow velocity of the traditional horizontally arranged copper pipe is 3.24 m / min. This indicates that there is no impedance in the stratosphere and no turbulence is formed.

[0092] Similarly, comparing the pressure difference results, the pressure difference value of the model with a 30° bend "horizontal-downward-upward" in this invention is 34029.4 N / m2; the pressure difference value of the traditional horizontally arranged copper pipe is 31616.9 N / m2, which also shows that under the principle of this invention, the stratosphere is broken and turbulence is formed.

[0093] Temperature conclusion: The chip center temperature of the copper tube arrangement with a 30° bend "horizontal-downward-upward" in this invention is 58.08°, while the temperature of the conventional horizontal copper tube arrangement is 61.04°. This also shows that under the action of turbulence, the coolant can exchange heat well with the copper tube wall, break the stratosphere, and transfer a large amount of heat to the coolant, thereby reducing the chip temperature by 3°.

[0094] Test data comparison table:

[0095] Liquid inlet temperature (°C) Ambient temperature (°C) Flow rate (liters / minute) Pressure difference (kPa) Design target temperature (°C) Simulated maximum temperature (°C) result Horizontal layout 35 35 6 31616.9 NA 61.04 This case 35 35 6 34029.4 NA 58.8 ↓3℃

[0096] The results show that, due to the turbulent flow effect, the heat exchange efficiency of the 30° curved copper tube liquid cooling plate is 5.17% higher than that of the horizontal copper tube liquid cooling plate. The improvement effect is even more significant when the power is doubled.

[0097] In summary, the technical solution of this invention has prominent substantive features and significant progress, specifically manifested as follows:

[0098] 1. Significantly improved heat exchange efficiency: This invention uses a bend unit at a specific angle in the straight section of the copper tube to force the coolant to form turbulence by a sudden change in the flow channel, breaking the laminar boundary layer limitation. Compared with the traditional straight tube M-type liquid cooling plate, the heat exchange coefficient is increased by more than 15%, which can effectively meet the high-efficiency heat dissipation requirements of high-power electronic devices and small battery modules.

[0099] 2. Controllable flow resistance increment: While enhancing heat exchange efficiency, this invention does not require additional built-in components. By optimizing the bending angle (30°), the flow resistance increment is controlled within 18%, avoiding the problem of a significant increase in energy consumption caused by adding built-in components and improving the economy of the heat dissipation system.

[0100] 3. High structural stability: The optimal bending angle range determined through theoretical derivation and parameter calculation can effectively avoid stress concentration during the bending process of copper tubes, preventing failure problems such as tube wall thinning and cracking, thus improving the structural stability and service life of the liquid cooling plate.

[0101] 4. Simple processing and manufacturing: The flow channel structure of the present invention is formed by directly bending copper tubes, without the need to add complex internal components. Moreover, the grooves are generated by conventional profile technology to form U-shaped grooves, which is easy to process, moderate in manufacturing cost, and easy to mass-produce.

[0102] 5. If the number of times the copper tube is bent is increased to 6, 8, or 12, and the power of the chip is increased to 2000, 5000, or 10000W, the effect of the present invention will be significantly improved.

[0103] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A turbulence-enhanced bent flow channel liquid cooling plate, characterized in that, It includes a substrate and a copper tube embedded in the substrate; the substrate surface has 4 embedded grooves; the copper tube is embedded in the embedded grooves, and the copper tube is continuously bent to form a series 4-channel flow channel; the straight section of the copper tube is provided with several sets of "horizontal-downward-lifting" bending units at intervals, and the bending angle of the bending unit is 30°.

2. The turbulence-enhanced bent flow channel liquid cooling plate according to claim 1, characterized in that, The substrate surface has four U-shaped flow channels, forming four embedded grooves.

3. The turbulence-enhanced bent flow channel liquid cooling plate according to claim 1, characterized in that, The copper tube is continuously bent to form a series M-shaped flow channel.

4. The turbulence-enhanced bent flow channel liquid cooling plate according to claim 1, characterized in that, The bending units are evenly spaced along the straight section of the copper tube.

5. The turbulence-enhanced bent flow channel liquid cooling plate according to claim 1, characterized in that, The bending unit has 3 sets.

6. The turbulence-enhanced bent flow channel liquid cooling plate according to claim 1, characterized in that, The four embedded grooves are arranged in parallel, and the cross-sectional shape of the grooves is adapted to the outer contour of the copper tube.

7. The turbulence-enhanced bent flow channel liquid cooling plate according to claim 1, characterized in that, The copper tube and the embedded groove are fixed by tight fitting riveting or thermally conductive adhesive bonding.

8. The turbulence-enhanced bent flow channel liquid cooling plate according to claim 1, characterized in that, The substrate is made of 6061 aluminum alloy and has dimensions of 152mm×127mm×17mm.

9. The turbulence-enhanced bent flow channel liquid cooling plate according to claim 1, characterized in that, The copper tube has an outer diameter of 9.52 mm, a wall thickness of 1.5 mm, and an inner diameter of 6.52 mm.

10. A manufacturing process for a turbulence-enhanced bent flow channel liquid-cooled plate as described in any one of claims 1-4, characterized in that, Includes the following steps: a) Prepare a 6061 aluminum alloy substrate and process four U-shaped embedded grooves using profile technology; b) Bend the copper tubes into a series M-type flow channel according to the design requirements, and set 30° bending units in the straight pipe sections; c) Embed the bent copper tube into the groove and fix it by riveting or bonding. d) Perform airtightness testing and surface treatment.

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