A multi-stage flow channel structure and method for water-cooled plate thermal management of new energy batteries

Abstract

This invention discloses a multi-stage flow channel structure and method for thermal management of new energy batteries using a water-cooled plate, relating to the field of vehicle power battery thermal management technology. The multi-stage flow channel structure includes a water-cooled plate body and a flow channel system disposed within it. The flow channel system includes an inlet flow channel, a secondary distribution flow channel, a tertiary distribution flow channel, and an outlet flow channel, with each stage of the flow channel connected sequentially. Based on the "flow distribution and equalization" principle of the Dujiangyan Irrigation System, the secondary and tertiary distribution flow channels adopt a gradient change design. This invention effectively solves the problems of significant temperature rise along the flow path, large temperature difference caused by uneven flow distribution, and poor temperature consistency in the water-cooled plate through structural innovation. It ensures that the maximum temperature difference on the surface of the water-cooled plate is ≤3℃, significantly improving the temperature uniformity, heat dissipation efficiency, and safety of the battery thermal management system. Furthermore, the structure is simple and the processing cost is low, making it suitable for battery thermal management in electric vehicles, energy storage systems, and other fields.

Description

Technical Field

[0001] This invention belongs to the field of battery thermal management technology, specifically relating to a thermal management device and method for new energy batteries (especially vehicle power batteries), and particularly to a water-cooled plate with a multi-level gradient flow channel structure based on the biomimetic shunt principle and its thermal management method. Background Technology

[0002] Against the backdrop of the global strategy of "peak carbon and carbon neutrality," electric vehicles, as an important carrier of green mobility, rely heavily on the performance and safety of their core component—the power battery. Lithium-ion batteries have a narrow optimal operating temperature range (generally 20℃-40℃), and the internal temperature difference of the battery pack must be controlled within 5℃ to slow down battery aging, prevent thermal runaway, and ensure range and safety.

[0003] Liquid cooling (especially water cooling) has become the mainstream thermal management method for high-energy-density battery packs due to its high heat capacity, high thermal conductivity, and stable and reliable characteristics. As a key component of the liquid cooling system, the flow channel structure design of the water cooling plate directly determines the flow distribution of the coolant, heat exchange efficiency, and uniformity of battery temperature.

[0004] Uneven flow distribution: In traditional parallel or serpentine flow channels, coolant tends to flow along the path with less resistance (usually the middle or short path), resulting in flow imbalance between channels and uneven cooling of the corresponding battery area.

[0005] Significant temperature rise along the process: The coolant continuously absorbs heat as it flows from the inlet to the outlet, causing the temperature to rise continuously. This reduces the temperature difference between the downstream battery and the coolant, decreases the heat exchange efficiency, and results in a higher temperature at the battery pack outlet.

[0006] Temperature uniformity is difficult to meet: The above two points work together to result in a large temperature difference between the surface of the water-cooled plate and the corresponding battery module, making it difficult to meet the stringent requirements of the battery for temperature uniformity (such as the ideal target of temperature difference ≤3℃).

[0007] Therefore, there is a need for a water-cooled plate flow channel structure and method that has a clear principle, simple structure, and can actively and accurately control the distribution of coolant flow, thereby achieving excellent temperature uniformity performance over a wide range of operating conditions. Summary of the Invention

[0008] The primary objective of this invention is to overcome the shortcomings of existing technologies, such as uneven distribution of coolant in the water-cooled plate flow channel, large temperature rise along the flow path, and excessive temperature difference in the battery pack. This invention provides a multi-stage flow channel structure for a water-cooled plate based on the biomimetic principle of "flow distribution and equalization" from the Dujiangyan Irrigation System.

[0009] The specific technical solution is as follows: The system includes a water-cooled plate body and a multi-stage flow channel system disposed inside the water-cooled plate body. The multi-stage flow channel system includes an inlet flow channel, a secondary flow channel, a tertiary flow channel and an outlet flow channel connected in sequence. As a further aspect of the present invention: the secondary diversion channel is composed of multiple parallel channels, from the first channel located on the outer side of the cold plate width direction to the fifth channel located in the middle, the height of each channel decreases sequentially and the width increases sequentially. As a further aspect of the present invention: the three-stage diversion channel is composed of multiple parallel channels, from the first channel located on the outer side of the cold plate width direction to the ninth channel located in the middle, the height of each channel decreases sequentially and the width increases sequentially. As a further aspect of the present invention: the secondary diversion channel includes 5 parallel channels, wherein the height of the first channel is 10mm, the height of the fifth channel is 6mm, the height of the middle channel decreases in a gradient, and the width of each channel increases from the outside to the middle. As a further aspect of the present invention: the three-stage diversion channel includes nine parallel channels, wherein the height of the first channel is 8mm, the height of the ninth channel is 4mm, the height of the middle channel decreases in a gradient, and the width of each channel increases from the outside to the middle. As a further aspect of the present invention: the height gradient change method of the secondary diversion channel is as follows: The height decreases by 2mm from the first channel to the third channel, and increases by 2mm from the third channel to the fifth channel. As a further aspect of the present invention: the height gradient change of the secondary diversion channel is as follows: from the first channel to the fifth channel, the height decreases by 1mm each time; As a further aspect of the present invention: the height gradient change method of the three-stage diversion channel is as follows: from the first channel to the fifth channel, the height decreases by 1mm, and from the fifth channel to the ninth channel, the height increases by 1mm. As a further aspect of the present invention: the height gradient of the three-stage diversion channel is as follows: from the first channel to the ninth channel, the height decreases by 0.5mm each time; As a further aspect of the present invention: the water-cooled plate body is made of aluminum alloy, and the coolant is water or an aqueous solution of ethylene glycol.

[0010] A multi-stage flow channel structure for a water-cooled plate used in thermal management of new energy batteries is provided. The structure includes a flat water-cooled plate body, internally formed with a multi-stage branch flow channel system that constitutes the coolant flow path. This system, along the coolant flow direction, includes, in sequence: Inlet channel: Used to connect to external cooling pipes and introduce coolant into the water-cooled plate.

[0011] Secondary distribution channel: Connected to the inlet channel, it is responsible for the initial distribution of coolant. This stage of the channel consists of several (preferably 5) parallel channels along the width of the cold plate. The key design feature is that the flow cross-section of each channel changes gradually from the outermost channels on both sides of the cold plate to the middle channels: the height decreases successively, and the width increases successively. For example, the outer channels can be designed as "deep and narrow" (e.g., 10mm high, relatively narrow), and the middle channels can be designed as "shallow and wide" (e.g., 6mm high, relatively wide).

[0012] As a further aspect of the invention: a three-stage diversion channel: connected to the two-stage diversion channel, responsible for a more refined second diversion. This stage of the channel consists of more (preferably 9) parallel channels. Similarly, from the outer channel to the middle channel, the height of each channel gradually decreases, while the width gradually increases. For example, the outer channel is 8mm high (deep and narrow), and the middle channel is 4mm high (shallow and wide).

[0013] Outlet channel: collects the coolant flowing out of each channel of the three-stage distribution channel and directs it to the water-cooled plate.

[0014] The core principle of this invention is based on the dynamic adaptive mechanism of the Dujiangyan "Fish Mouth" water diversion project, which utilizes the river's geometric shape (depth and width) to automatically adjust the diversion ratio between the inner and outer rivers under different water levels (flow rates). In this invention: The "dry season (low flow)" is analogous to when the overall coolant flow rate is small: because the outer flow channel is deeper and the flow resistance is relatively small, the coolant tends to flow more into the outer "deep and narrow" flow channel.

[0015] The "flood season (high flow rate)" is analogous to when the total flow rate of coolant is large: as the flow rate increases, the water level (the height of the liquid surface in the flow channel) rises, and the "shallow and wide" middle flow channel begins to show its advantage due to its larger top flow area, which can divert more liquid and prevent the outer flow channel from being overloaded.

[0016] Through this gradient geometric design, the coolant flow rate is adaptively redistributed in the width direction of the cold plate (corresponding to the high-temperature and low-temperature areas of the battery) according to the total flow rate and local flow resistance, thereby actively "compensating for the flow rate" in the high-temperature area and achieving the purpose of temperature uniformity.

[0017] Another objective of this invention is to provide a battery thermal management method that applies the above-mentioned flow channel structure to achieve adaptive and optimized distribution of coolant flow rate, thereby ensuring high temperature uniformity of the water-cooled plate and battery module under a wide range of operating conditions.

[0018] Preferably, it includes the following steps: Step S1: Install the water-cooled plate multi-stage flow channel structure below or to the side of the battery module, and set a thermally conductive interface material between the battery module and the contact surface of the cold plate. Step S2: The coolant enters the water-cooled plate through the inlet channel, flows through the secondary and tertiary distribution channels in sequence, absorbs the heat generated by the battery, and then flows out from the outlet channel. Step S3: Through the gradient-changing flow channel structure, the flow distribution of each parallel channel is dynamically adjusted during the secondary and tertiary flow splitting process, so that more coolant flows to the outer area with higher temperature, thereby achieving temperature compensation and ensuring the uniformity of surface temperature of the water-cooled plate. Preferably, the inlet temperature of the coolant is 15℃-25℃, the flow rate is 200-400L / h, the heating power of the battery module is 10-20W / cell, and the maximum temperature difference on the surface of the water-cooled plate does not exceed 3℃.

[0019] The water-cooled plate is integrated into the thermal management system of the battery module to ensure good thermal contact.

[0020] The pumped coolant flows through the water-cooled plate according to the set operating conditions (e.g., inlet temperature 20℃, flow rate 300L / h).

[0021] When the coolant flows through the secondary and tertiary gradient distribution channels, its flow rate is automatically redistributed according to the geometric gradient of the channels, and more coolant is directed to the areas that need enhanced cooling (usually the two sides with higher temperatures).

[0022] Through this dynamic adjustment process, the surface temperature field of the water-cooled plate after absorbing the heat from the battery is made highly uniform, ultimately achieving effective control of the overall temperature difference of the battery pack (e.g., ≤3℃).

[0023] Compared with the prior art, the beneficial effects of the present invention by adopting the above technical solution are as follows: 1. This invention achieves intelligent spatial distribution of coolant flow rate through a biomimetic gradient flow channel design, fundamentally improving temperature uniformity. Simulation and experiments show that the optimal solution of this invention (such as solution three) can keep the maximum temperature difference on the surface of the water-cooled plate within 3℃, which is significantly better than the traditional flow channel structure. 2. This invention enhances the robustness and adaptability of the system under different heat loads or pump operation conditions by automatically fine-tuning the split ratio according to changes in total flow rate through the flow channel structure itself. 3. This invention uses a gradient combination of straight parallel channels with a regular and symmetrical layout, eliminating the need for complex curved surfaces or microstructures. It is particularly suitable for mass production using processes such as extrusion, stamping, milling, or 3D printing, and the cost is controllable. 4. This invention optimizes flow distribution through gradient design, while also helping to smooth the flow, reducing flow dead zones and vortices at bends, reducing unnecessary pressure drops, and improving overall heat exchange efficiency.

[0024] 5. The present invention has a clear design concept based on the Dujiangyan diversion principle. By adjusting parameters such as the gradient level, the number of channels, and the height and width change rate, it can be easily adapted to battery packs of different sizes and heat loads, and has good design scalability. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall three-dimensional geometric model of the battery pack using the water-cooled plate structure of this invention; Figure 2 This is a schematic plan view of the water-cooled plate flow channel structure according to a specific embodiment of the present invention.

[0026] Figure 3 It corresponds Figure 2 The simulation analysis yielded a cloud map of the heat source temperature distribution above the water-cooled plate. Figure 4 This is a schematic diagram of the cross-section of the water-cooled plate flow channel according to a specific embodiment of the present invention.

[0027] In the diagram: 1. Water-cooled plate body; 2. Inlet channel; 3. Secondary diversion channel; 4. Tertiary diversion channel; 5. Outlet channel. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0029] The multi-stage flow channel structure of the water-cooled plate of the present invention serves as the core heat dissipation component of the battery thermal management system (BTMS). It is typically installed at the bottom or side of the battery module. The heat generated by the battery module is transferred to the surface of the water-cooled plate through a thermal interface material (such as a thermally conductive silicone pad) and carried away by the internally flowing coolant. The circulation of the coolant is driven by a circulation system composed of external pumps, pipelines, radiators, and other components. Example 1:

[0030] like Figure 1 Figure 2 As shown, this embodiment demonstrates a symmetrical parallel multi-stage flow channel structure without gradient design, for comparison with the optimized scheme of the present invention; Structural parameters: The overall dimensions of the water-cooled plate are 1088mm × 770mm × 10mm. The flow channel height is uniformly 5mm. The secondary distribution channel contains 5 parallel channels of equal width and height. The tertiary distribution channel 4 contains 9 parallel channels of equal width and height.

[0031] Simulation conditions: Battery module: 52 square LFP cells, arranged in 4 rows and 13 columns, with a single cell generating 15W of heat, simplified as a uniform heat source; Cooling medium: water, inlet temperature 20℃, mass flow rate 0.0832 kg / s (approximately 300 L / h).

[0032] Boundary conditions: The contact surface between the cold plate and the battery is a constant heat flux density boundary (1183.9 W / m²). The outer surface of the cold plate is subject to natural convection; the inlet is a mass flow inlet, and the outlet is a pressure outlet. Material properties: The water-cooled plate is made of 6061 aluminum alloy; the cooling water properties are constant. Solution setup: CFD method is used, the flow is turbulent (Re>4000), SST k-ω turbulence model is selected, and the energy and momentum equations are solved in a coupled manner; Simulation result analysis: such as Figure 3 As shown in the temperature cloud map, the temperature of the heat source (representing the battery) gradually increases along the coolant flow direction. In the latter half of the flow channel (near the outlet), a significant difference in temperature between the sides and the middle is observed. Flow field analysis indicates that due to the relatively low flow resistance in the middle channel, most of the coolant preferentially flows through the middle region, resulting in insufficient flow allocated to the sides. This leads to poor heat dissipation from the batteries on both sides, amplifying the temperature difference. This result highlights the decisive impact of uneven flow distribution on temperature uniformity. Example 2:

[0033] To address the traffic imbalance problem in Solution 1, this embodiment proposes a first gradient optimization design, such as... Figure 2 As shown.

[0034] Structural improvements: Secondary diversion channel 3: contains 5 channels (31-35). The channel height decreases by 2mm from 10mm in the outer channel 31 to 6mm in the middle channel 33, and then increases by 2mm to 10mm in the other outer channel 35. The width of each channel increases from the outside to the middle.

[0035] Three-level diversion channel 4: contains 9 channels (41-49). The channel height decreases by 1 mm from 8 mm in the outer channel 41 to 4 mm in the middle channel 45, and then increases by 1 mm to 8 mm in the outer channel 49. The width of each channel increases from the outside to the middle. Simulation result analysis: such as Figure 3 As shown in the temperature cloud map, compared with Scheme 1, the temperature distribution of Scheme 2 is significantly improved. The high-temperature area on both sides of the heat source in the latter half of the flow channel is reduced and the temperature value is lowered. This is because the gradient design of "deep and narrow on the outside and shallow and wide on the inside" adjusts the flow resistance distribution during flow, increases the proportion of coolant flowing to both sides of the channel, thereby strengthening the cooling effect on both sides of the battery and improving the overall temperature uniformity. Example 3:

[0036] Based on Scheme 2, further simplification and optimization are carried out to form the preferred scheme of the present invention, with structural improvements: Secondary diversion channel 3: contains 5 channels (31-35), the channel height decreases linearly from 10mm in the outer channel 31 to 6mm in the middle channel 35 (the height difference between adjacent channels is 1mm), and the width of each channel increases from the outside to the middle; The three-level diversion channel 4 contains 9 channels (41-49). The channel height decreases linearly from 8 mm for the outer channel 41 to 4 mm for the middle channel 49 (the height difference between adjacent channels is 0.5 mm). The width of each channel increases from the outer side to the middle.

[0037] Simulation result analysis: such as Figure 3 As shown in the temperature cloud map, Scheme 3 exhibits the best temperature uniformity, with the most uniform temperature field distribution and effective suppression of high-temperature areas. The flow distribution comparison chart quantitatively shows that after the three-stage flow split, Scheme 3 successfully distributes more coolant to the outer channels (41, 49, etc.), achieving the design intent.

[0038] Quantization performance comparison: To objectively evaluate the uniformity of flow distribution, two indicators are introduced: "standard deviation of flow distribution (σ)" and "uniformity (Uni)". The calculation results are summarized in... Figure 3 And the following table:

[0039] The smaller the standard deviation (σ), the closer the uniformity (Uni) is to 1, indicating a more even flow distribution. Scheme 3 has the minimum σ and the maximum Uni at both the secondary and tertiary flow splits, proving that its gradient design achieves optimal flow balance distribution in both flow splits. Ultimately, Scheme 3 successfully controls the maximum temperature difference on the water-cooled plate surface within 3℃, fully meeting the stringent requirements for high-consistency battery thermal management.

[0040] Working principle: Material selection: The water-cooled plate body 1 is preferably made of aluminum alloy with good thermal conductivity, low density and corrosion resistance (such as 6061, 5052, etc.). The coolant can be water, ethylene glycol aqueous solution or other industrial coolant. Manufacturing process: Any or a combination of the following processes can be used: 1) Extrusion molding of aluminum profile followed by sealing welding; 2) Processing flow channel grooves on aluminum plate by CNC milling or chemical etching, followed by brazing or friction stir welding to cover the cover plate; 3) Using 3D printing (such as metal powder sintering) to integrally form complex flow channel structures; System integration: The water-cooled plate is fixed to the battery box or module bracket with bolts or adhesive. High-performance thermal pads or thermal grease are applied between the battery and the cold plate to reduce contact thermal resistance. The inlet and outlet of the cold plate are connected to the external cooling pipeline through quick-connect fittings or welding.

[0041] The flow channel of this invention exhibits dynamic adjustment characteristics during operation: During startup / low load phase: The initial flow rate of the coolant is relatively small. At this time, the "deep and narrow" outer flow channel exhibits lower flow resistance due to its relatively small flow cross-section (although deep, it is narrow, and the overall hydraulic diameter may be better). Naturally, more coolant flows into the outer flow channel, preferentially cooling the battery edge area, which is usually more prone to overheating.

[0042] Normal / High Load Phase: As battery heat generation increases or system requirements increase, the total coolant flow rate increases. When the flow rate increases to a certain extent, the fluid filling degree in the flow channel increases. The "shallow and wide" middle flow channel has a larger upper edge flow width, and its flow capacity increases faster, starting to divert more liquid. This prevents the pressure loss from increasing sharply due to excessive flow in the outer flow channel, while ensuring that the battery in the middle area can also receive sufficient cooling.

[0043] This passive dynamic distribution based on the geometry of the flow channel itself can adapt to different heat loads and flow rate conditions to a certain extent and achieve balanced global temperature control without the need for sensors or active valve control.

[0044] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A multi-stage flow channel structure for a water-cooled plate used in thermal management of new energy batteries, characterized in that, It includes a water-cooled plate body (1) and a multi-stage diversion channel system disposed inside the water-cooled plate body (1). The multi-stage diversion channel system includes an inlet channel (2), a secondary diversion channel (3), a tertiary diversion channel (4), and an outlet channel (5) connected in sequence. The secondary diversion channel (3) consists of multiple parallel channels, from the first channel located on the outer side of the cold plate width direction to the fifth channel located in the middle, the height of each channel decreases sequentially and the width increases sequentially. The three-stage diversion channel (4) consists of multiple parallel channels, from the first channel located on the outer side of the cold plate width direction to the ninth channel located in the middle, the height of each channel decreases sequentially and the width increases sequentially.

2. The water-cooled plate multi-stage flow channel structure according to claim 1, characterized in that: The secondary diversion channel (3) contains 5 parallel channels, of which the height of the first channel is 10mm, the height of the fifth channel is 6mm, the height of the middle channel decreases in a gradient, and the width of each channel increases from the outside to the middle.

3. The water-cooled plate multi-stage flow channel structure according to claim 1, characterized in that: The three-level diversion channel (4) contains 9 parallel channels, of which the height of the first channel is 8mm, the height of the ninth channel is 4mm, the height of the middle channel decreases in a gradient, and the width of each channel increases from the outside to the middle.

4. The water-cooled plate multi-stage flow channel structure according to claim 2, characterized in that: The height gradient change method of the secondary diversion channel (3) is as follows: The height decreases by 2mm from the first channel to the third channel, and increases by 2mm from the third channel to the fifth channel.

5. The water-cooled plate multi-stage flow channel structure according to claim 2, characterized in that: The height gradient of the secondary diversion channel (3) is such that the height decreases by 1 mm from the first channel to the fifth channel.

6. The water-cooled plate multi-stage flow channel structure according to claim 3, characterized in that: The height gradient of the three-stage diversion channel (4) is as follows: from the first channel to the fifth channel, the height decreases by 1 mm, and from the fifth channel to the ninth channel, the height increases by 1 mm.

7. The water-cooled plate multi-stage flow channel structure according to claim 3, characterized in that: The height gradient of the three-stage diversion channel (4) is as follows: from the first channel to the ninth channel, the height decreases by 0.5 mm.

8. The water-cooled plate multi-stage flow channel structure according to any one of claims 1-7, characterized in that: The water-cooled plate body (1) is made of aluminum alloy, and the coolant is water or ethylene glycol aqueous solution.

9. A thermal management method for thermal management of new energy batteries, characterized in that, The water-cooled plate multi-stage flow channel structure as described in any one of claims 1-8 includes the following steps: Step S1: Install the multi-stage flow channel structure of the water-cooled plate below or to the side of the battery module, and set a thermally conductive interface material between the battery module and the contact surface of the cold plate. Step S2: The coolant enters the water-cooled plate through the inlet channel (2), flows through the secondary branch channel (3) and the tertiary branch channel (4) in sequence, absorbs the heat generated by the battery, and then flows out from the outlet channel (5); Step S3: Through the gradient-changing flow channel structure, the flow distribution of each parallel channel is dynamically adjusted during the secondary and tertiary flow splitting process, so that more coolant flows to the outer area with higher temperature, thereby achieving temperature compensation and ensuring the uniformity of the surface temperature of the water-cooled plate.

10. The thermal management method according to claim 9, characterized in that: The inlet temperature of the coolant is 15℃-25℃, the flow rate is 200-400L / h, the heating power of the battery module is 10-20W / cell, and the maximum temperature difference on the surface of the water-cooled plate does not exceed 3℃.

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