A lithium ion battery air-cooled thermal management system and a multi-objective optimization method thereof

Abstract

The present application relates to a lithium ion battery air-cooled thermal management system and a multi-objective optimization method thereof, wherein a first wall surface of a battery box is provided with an air inlet, and a second wall surface is provided with an air outlet; a middle cooling channel is formed between adjacent cylindrical battery cells of a battery module, and an outer peripheral cooling channel is formed between the outer periphery of the battery module and the side wall of the battery box; a flow guide plate is arranged between the air inlet and the battery module, and a center through hole is arranged corresponding to the position of the air inlet and the middle cooling channel; an outer peripheral flow gap is formed between the outer edge of the flow guide plate and the spacing area of the side wall of the battery box, and the outer peripheral flow gap is in communication with the outer peripheral cooling channel. The optimization method performs multi-objective optimization on the length of the flow guide plate and the size of the center through hole by establishing a CFD model, Latin hypercube sampling, a Kriging surrogate model and a non-dominated sorting genetic algorithm. The present application utilizes the center through hole of the flow guide plate to simultaneously organize the inlet air flow into a center straight-through path and an outer peripheral flow path, which can coordinate the cooling air volume of the middle and outer peripheral areas of the battery module, reduce the highest temperature and improve temperature uniformity.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery thermal management technology, and particularly relates to a lithium-ion battery air-cooled thermal management system and its multi-objective optimization method. Background Technology

[0002] Lithium-ion batteries are characterized by high energy density, long cycle life, and good power performance, and are widely used in new energy vehicles and electrochemical energy storage systems. During charging and discharging, lithium-ion batteries generate heat due to ohmic internal resistance, polarization, and electrochemical reactions. If this heat cannot be dissipated in time, the maximum temperature of the battery module and the temperature difference between different cells will increase, easily leading to inconsistent cell aging rates, accelerated capacity decay, and in severe cases, even thermal runaway.

[0003] Air cooling has advantages such as simple structure, low cost, convenient maintenance, and no risk of coolant leakage. However, in air-cooled structures where the air inlet and outlet are located in the middle of opposite walls of the battery box, the airflow tends to flow directly from the central area of ​​the battery module, where resistance is low, to the outlet, creating a high-speed airflow in the central area. Meanwhile, the airflow in the outer area of ​​the battery module is insufficient, resulting in a mismatch in cooling intensity between the central and outer cells.

[0004] To improve airflow distribution, existing technologies typically employ methods such as adjusting the positions of the air inlet and outlet, changing the cell arrangement, adding perforated baffles, or setting up perforated distribution plates. However, perforated baffles tend to excessively suppress the central flow, while perforated distribution plates usually supply air to different areas through multiple discrete openings. Their structure and airflow organization do not fully correspond to the coordinated distribution requirement of "retaining direct airflow in the central area and forming surrounding airflow in the peripheral area."

[0005] In addition, the length of the guide plate, the size of the central through hole, and the ratio of the two together affect the airflow distribution in the central and peripheral areas. Single-factor experiments or a small number of parameter combinations cannot simultaneously take into account the highest temperature of the battery module, the maximum temperature difference, and the temperature dispersion of each cell. If high-fidelity computational fluid dynamics simulation is performed directly on all parameter combinations, the computational cost will be high.

[0006] Therefore, it is necessary to provide a dual-path air-cooled thermal management system with a clearly defined structural relationship, and to provide an efficient parameter optimization method that matches this structure. Summary of the Invention

[0007] The present invention addresses the problems existing in the prior art, namely, the technical problem to be solved by the present invention is to provide a lithium-ion battery air-cooled thermal management system and its multi-objective optimization method.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a lithium-ion battery air-cooled thermal management system, comprising a battery box with battery modules disposed inside, the battery box having a first wall and a second wall disposed opposite to each other, the first wall having an air inlet, and the second wall having an air outlet corresponding to the position of the air inlet; the battery module comprising a plurality of spaced cylindrical cells, with a central cooling channel formed between adjacent cylindrical cells, and an outer peripheral cooling channel formed between the outer periphery of the battery module and the side wall of the battery box; a guide plate is disposed parallel to the air inlet and the battery module, the central region of the guide plate having a central through hole, the central through hole corresponding to and communicating with the air inlet and the central cooling channel; the outer edge of the guide plate is spaced apart from the side wall of the battery box, and the spaced area forms an outer peripheral flow gap, the outer peripheral flow gap communicating with the outer peripheral cooling channel.

[0009] Furthermore, the axes of the air inlet, the central through hole, and the air outlet coincide; the projection of the central through hole onto the battery module is located in the central region of the battery module.

[0010] Furthermore, the outer edges of each side of the guide plate form an external flow gap with the adjacent battery box sidewall.

[0011] Furthermore, the guide plate is a square flat plate, and the side length of the guide plate is... l The diameter of the central through hole is D 35 mm≤ l ≤55 mm, 5 mm≤ D ≤30 mm, and 1 / 6≤ D / l ≤2 / 3.

[0012] Furthermore, 40 mm ≤ l ≤50 mm, 14 mm≤ D ≤22 mm, and 0.30≤ D / l ≤0.50.

[0013] Furthermore, the central through hole is a circular through hole.

[0014] Furthermore, the first wall is located at the top of the battery box, and the second wall is located at the bottom of the battery box; the guide plate is parallel to the first wall, and the distance between the surface of the guide plate facing the battery module and the top surface of the cylindrical cell is 1-3mm.

[0015] Another technical solution adopted in this invention is: a multi-objective optimization method for a lithium-ion battery air-cooled thermal management system, comprising the following steps: Step S1: Obtain the structural parameters, thermal properties, and operating parameters of the battery box, battery module, air guide plate, and air, and establish a CFD model for the air-cooled thermal management of lithium-ion batteries; Step S2: Perform a grid independence test on the CFD model of air-cooled thermal management of lithium-ion battery established in step S1, and verify the model using cell temperature data at at least two discharge rates. Step S3: Under the condition that the central through-hole area is the same, compare at least two central through-hole shapes, and determine the central through-hole shape according to the highest temperature and the maximum temperature difference of the battery module; Step S4: Using the side length of the deflector l Equivalent diameter of the center through hole D As design variables, sample points are generated within a preset design space, and the highest temperature corresponding to each sample point is calculated using a CFD model of lithium-ion battery air-cooled thermal management. T max Maximum temperature difference Δ T and temperature standard deviation S ; Step S5: Based on the sample points generated in step S4 and their corresponding... T max Δ T and S Training the Kriging agent model; Step S6: with T max Δ T and S Simultaneously, with the minimum as the optimization objective, a Pareto optimal solution set is obtained using a non-dominated sorting genetic algorithm based on the Kriging surrogate model; Step S7: Select candidate design schemes from the Pareto optimal solution set, and substitute the candidate design schemes back into the lithium-ion battery air-cooling thermal management CFD model for verification to determine the final design scheme.

[0016] Furthermore, in step S3, the central through-holes of circles, squares, and equilateral triangles are compared, and it is determined that the central through-hole is circular; in step S4, Latin hypercube sampling is used to generate 52 sets of sample points, and 35 mm ≤ l ≤55 mm, 0 mm≤ D ≤30mm, 1 / 6≤ D / l ≤2 / 3.

[0017] Furthermore, in step S5, the coefficient of determination R², mean absolute error (MAE), and root mean square error (RMSE) are used to evaluate the Kriging surrogate model. T max Δ T and SThe corresponding R² values ​​are all greater than 0.95; in step S6, the non-dominated sorting genetic algorithm is NSGA-II, the population size is 100, the maximum number of iterations is 500, and the crossover probability is 0.8.

[0018] Compared with the prior art, the present invention has the following effects: (1) The central through hole retains the necessary flow capacity of the central region, avoiding the complete blockage of central cooling by the guide plate; (2) The peripheral flow gap between the outer edge of the guide plate and the side wall of the battery box guides another part of the airflow to the periphery of the battery module, increasing the cooling airflow near the peripheral cells; (3) The central through path and the outer surrounding flow path are formed by the same guide plate at the same time, which can coordinate the heat exchange intensity of the central and peripheral regions; (4) The number of high-fidelity simulations is reduced by proxy model and multi-objective optimization algorithm, while taking into account the highest temperature, the maximum temperature difference and the overall temperature uniformity; (5) Compared with the original system without the central through hole guide plate, the highest temperature, the maximum temperature difference and the temperature standard deviation of the optimized scheme are reduced by 13.12%, 47.77% and 94.93%, respectively. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the main structure of the present invention; Figure 2 This is a top view of the structure of the present invention; Figure 3 This is a schematic diagram of the construction of central through holes of different shapes in this invention; Figure 4 This is a comparative schematic diagram showing the airflow distribution principle with and without a central through-hole guide plate; Figure 5 This is a flowchart of the multi-objective optimization method of the present invention; Figure 6 This is a schematic diagram of the internal structure of the present invention.

[0020] In the picture: 1-Battery box; 11-First wall; 12-Second wall; 13-Side wall; 2-Air inlet; 3-Air outlet; 4-Battery module; 41-Cylindrical cell; 42-Central cooling channel; 43-Outer cooling channel; 5-Guide plate; 51-Plate body; 52-Central through hole; 53-Support rib; 6-Central straight path; 7-Outer surrounding flow path. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0023] like Figures 1-6 As shown, this invention discloses a lithium-ion battery air-cooled thermal management system that utilizes a central through-hole guide plate to simultaneously organize the incoming airflow into a central straight path and an outer surrounding flow path. It aims to solve the problems of airflow concentration in the middle of the battery module, insufficient cooling of the peripheral cells, and difficulty in coordinating the parameters of the guide plate in traditional air-cooled battery thermal management systems. The system includes a battery box 1 containing battery modules 4. The battery box 1 has a first wall 11 and a second wall 12 arranged opposite each other. An air inlet 2 communicating with the inner cavity of the battery box is located in the middle of the first wall 11. The second wall 12... An air outlet 3 corresponding to the position of the air inlet 2 is provided in the middle of the surface 12, and the air outlet 3 is connected to the inner cavity of the battery box 1; the battery module 4 includes a plurality of spaced cylindrical cells 41, and a central cooling channel 42 is formed between adjacent cylindrical cells 41, and an outer cooling channel 43 is formed between the outer periphery of the battery module 4 (that is, the cylindrical cells 41 located on the outer periphery of the array) and the side wall 13 of the battery box 1; the central cooling channel 42 and the outer cooling channel 43 both extend along the axial direction of the cylindrical cells 41 from one side of the first wall surface 11 to one side of the second wall surface 12. The specific improvements are as follows: a guide plate 5 is arranged parallel to the air inlet 2 and the battery module 4. The guide plate 5 is perpendicular to the air inlet 2 and has a central through hole 52 extending along the thickness direction in its central area. The central through hole 52 corresponds to and is connected to the air inlet 2 and the central cooling channel 42. The outer edge of the guide plate 5 is spaced apart from the side wall 13 of the battery box, and the spaced area forms an outer flow gap. The outer flow gap is connected to the outer cooling channel 43. A portion of the cooling air entering from the air inlet 2 flows sequentially through the central through hole 51 and the central cooling channel 42 to the air outlet 11 to form a central straight path 6. Another portion is blocked by the guide plate 5 and flows outward along the windward side of the guide plate 5, and sequentially through the outer flow gap and the outer cooling channel 43 to the air outlet 3 to form an outer surrounding flow path 7.

[0024] More specifically, the axes of the air inlet 2, the central through hole 52, and the air outlet 3 coincide or substantially coincide; the projection of the central through hole 52 on the battery module 4 is located in the central region of the battery module 4.

[0025] More specifically, the guide plate 5 includes a plate body 51 with a square flat plate structure. The outer edges of each side of the plate body 51 form an outer flow gap with the adjacent battery box side wall 13. The central through hole 52 is preferably a circular through hole.

[0026] More specifically, the side length of the plate 51 l The diameter of the central through hole 52 is D 35 mm≤ l ≤55mm, 5 mm≤ D ≤30 mm, and 1 / 6≤ D / l ≤2 / 3. Preferably, 40 mm≤ l ≤50 mm, 14 mm≤ D ≤22 mm, and 0.30≤ D / l ≤0.50.

[0027] More specifically, the first wall surface 11 is located at the top of the battery box 1, and the second wall surface 12 is located at the bottom of the battery box 1; the guide plate 5 is parallel to the first wall surface 11, and the thickness of the guide plate 5 is 2 to 4 mm; the distance between the surface of the guide plate 5 facing the battery module 4 and the top surface of the cylindrical cell 41 is 1 to 3 mm.

[0028] More specifically, the battery module 4 includes 16 18650 cylindrical cells 41, which are arranged in a 4×4 array with a spacing of 2 mm between adjacent cylindrical cells 41; the length, width and height of the battery box 1 are 86 mm, 86 mm and 89 mm respectively, and the diameter of the air inlet 2 and the air outlet 3 are both 30 mm.

[0029] More specifically, the guide plate 5 is made of aluminum or aluminum alloy and is fixed to the side wall 13 of the battery box by at least two support ribs 53 arranged around the central through hole. The support ribs 53 avoid the main flow area of ​​the central through hole 52 and the peripheral flow gap to reduce additional flow resistance.

[0030] When the system is operating, cooling air enters the area above the plate 51 through the air inlet 2. A portion of the airflow near the center of the air inlet 2 enters the central cooling channel 42 through the central through-hole 52 and flows axially along the cylindrical cell 41 towards the air outlet 3, forming a central straight path 6. The remaining airflow is blocked by the plate 51 and diffuses outwards along the windward side of the plate 51. It then turns through the peripheral flow gap between the outer edge of the plate 51 and the side wall 13 and enters the peripheral cooling channel 43, before flowing axially along the cylindrical cell 41 towards the air outlet 3, forming an outer surrounding flow path 7. The two paths converge at the air outlet 3 downstream.

[0031] The central through path 6 is used to maintain the cooling capacity of the central area of ​​the battery module 4, while the outer surrounding flow path 7 is used to increase the airflow in the peripheral area. By changing the size of the plate 51 and the size of the central through hole 52, the flow ratio of the two paths can be adjusted to make the heat exchange intensity between the central cell and the peripheral cell more balanced.

[0032] The multi-objective optimization method for the air-cooled thermal management system of this lithium-ion battery, such as Figure 5 As shown, it includes the following steps: Step S1: Obtain the structural parameters, thermal properties, and operating parameters of the battery box, battery module, air guide plate, and air, and establish a CFD model for the air-cooled thermal management of lithium-ion batteries (CFD model is also called a numerical simulation model in computational fluid dynamics). Step S2: Perform a grid independence test on the CFD model of air-cooled thermal management of lithium-ion battery established in step S1, and verify the model using cell temperature data at at least two discharge rates. Step S3: Under the condition that the central through-hole area is the same, compare at least two central through-hole shapes, and determine the central through-hole shape according to the highest temperature and the maximum temperature difference of the battery module; Step S4: Using the side length of the deflector l Equivalent diameter of the center through hole D As design variables, sample points are generated within a preset design space, and the highest temperature corresponding to each sample point is calculated using a CFD model of lithium-ion battery air-cooled thermal management. T max Maximum temperature difference Δ T and temperature standard deviation S ; Step S5: Based on the sample points generated in step S4 and their corresponding... T max Δ T and S Training the Kriging agent model; Step S6: with T max Δ T and S Simultaneously, with the minimum as the optimization objective, a Pareto optimal solution set is obtained using a non-dominated sorting genetic algorithm based on the Kriging surrogate model; Step S7: Select candidate design schemes from the Pareto optimal solution set, and substitute the candidate design schemes back into the lithium-ion battery air-cooling thermal management CFD model for verification to determine the final design scheme.

[0033] Furthermore, in this optimization method, step S3 compares the central through holes of circles, squares, and equilateral triangles, and determines that the central through hole is circular.

[0034] Furthermore, in this optimization method, step S4 uses Latin hypercube sampling to generate 52 sets of sample points, and 35mm ≤ l ≤55 mm, 0 mm≤ D ≤30 mm, 1 / 6≤ D / l ≤2 / 3.

[0035] Furthermore, in this optimization method, step S5 uses the coefficient of determination R², mean absolute error (MAE), and root mean square error (RMSE) to evaluate the Kriging surrogate model. T max Δ T and S The corresponding R² values ​​are all greater than 0.95.

[0036] Furthermore, in this optimization method, the non-dominated sorting genetic algorithm in step S6 is NSGA-II, the population size is 100, the maximum number of iterations is 500, and the crossover probability is 0.8.

[0037] Furthermore, in this optimization method, in the final design scheme determined in step S7, the side length of the plate is... l The diameter of the central through hole is 43.10 mm. D It is 17.10 mm. D / l It is 0.397. Example

[0038] In a specific structure, battery module 4 includes 16 18650 cylindrical cells 41, arranged in a 4×4 array; the spacing between adjacent cylindrical cells 41 is 2 mm, and the distance between the top surface of a cylindrical cell 41 and the first wall surface 11 is 15 mm. The battery box 1 has a length, width, and height of 86 mm, 86 mm, and 89 mm, respectively, and a wall thickness of 2 mm; the diameters of the air inlet 2 and air outlet 3 are both 30 mm. The initial side length of the guide plate 5 is... l The diameter of the center through hole is 35 mm. D The diameter is 18 mm, the plate thickness is 3 mm, and the distance between the bottom surface of the plate and the top surface of the cylindrical cell 41 is 18 mm. b It is 2 mm.

[0039] In this embodiment, a three-dimensional lithium-ion battery air-cooled thermal management model is established to evaluate the above structure. Air is treated as an incompressible fluid in the model, radiative heat transfer is ignored, and it is assumed that the thermal properties of the air, battery, and guide plate materials remain constant within the calculation temperature range. The air inlet 2 adopts a velocity inlet boundary, and the air outlet 3 adopts a pressure outlet boundary with a relative pressure of 0 Pa; the flow channel wall adopts a no-slip boundary, and the boundary between the outer wall of the battery box 1 and the ambient air adopts a natural convection boundary.

[0040] Under the conditions of an inlet air temperature of 25 ℃, an inlet wind speed of 2 m / s, and an inlet hydraulic diameter of 30 mm, the inlet Reynolds number is approximately 4106. The airflow is solved using the standard k-ε turbulence model. The discharge heat generation of the cylindrical battery cell 41 is described using a volumetric heat source, and the cylindrical battery cell 41 and the air are subjected to conjugate heat transfer conditions.

[0041] Table 1. Main material thermophysical parameters

[0042] At discharge rates of 1 C, 2 C, and 3 C, the volumetric heat generation rates of the cylindrical cell 41 are set to 5417 W / m³, 31728 W / m³, and 62175 W / m³, respectively.

[0043] Table 2 Cell volumetric heat generation rate at different discharge rates

[0044] Using the highest temperature T max Maximum temperature difference Δ T Temperature standard deviation S and pressure drop Δ p Evaluate thermal management performance. Among them, Δ T = T max - T min ; S =[(1 / n )Σ(T i,max - T max )²] 1 / 2 In the formula, T min This is the lowest temperature for battery module 4. T i,max For the first i The highest temperature of a cylindrical cell 41 T max This represents the average of the highest temperatures of all cylindrical cells. n This refers to the number of cylindrical battery cells.

[0045] A grid irrelevance test was performed. When the grid size reached 443,817, the changes in pressure drop and maximum temperature difference with increasing grid size were both less than 1%. Therefore, approximately 443,817 grids were selected for subsequent calculations. Experimental temperature data at 2C and 3C discharge rates were used to validate the model. The maximum relative error of the highest temperature under 2C conditions was 3.76%, and the calculated results under 3C conditions were basically consistent with the experimental results, indicating that the established model can be used to evaluate the impact of the central through-hole guide plate on airflow distribution and battery temperature.

[0046] In this embodiment, as Figure 3 As shown, under the condition that the area of ​​the central through hole is the same, circular, square and equilateral triangular central through hole structures are established respectively, while keeping the plate size, battery box size, cell arrangement, inlet and outlet size, inlet wind speed and cell heat generation rate unchanged.

[0047] Calculation results show that the highest temperature and maximum temperature difference corresponding to the circular central through-hole are lower than those of the square and equilateral triangular central through-holes, while the temperature standard deviation and pressure drop differences among the three types of central through-holes are relatively small. The sharp corners of the square and equilateral triangular central through-holes cause abrupt changes in the curvature of the hole edge and alter the local airflow direction; the continuous and smooth edges of the circular central through-hole are conducive to forming a more stable central straight airflow. Therefore, the circular central through-hole is preferred in this embodiment.

[0048] The diameter of the circular central through hole D With the side length of the square plate l The ratio is defined as the aperture ratio. α ,Right now α = D / l Parameter analysis shows that, α When the flow rate is too low, the flow rate of the central through path 6 is insufficient, and the cooling of the central battery cell is inadequate. α When the size is too large, the guiding effect of the plate 51 on the external flow path 7 is weakened, resulting in insufficient cooling of the peripheral battery cells. For the structure of this embodiment, α It exhibits good overall cooling performance when the temperature is 2 / 6 to 3 / 6.

[0049] Plate side length l When the size is too small, the plate 51 has insufficient ability to distribute the incoming airflow to the periphery; the side length of the plate... l If the clearance is too large, the peripheral flow gap will shrink, potentially increasing flow resistance and inhibiting peripheral flow. Therefore, it can be... l The preliminary design range is set at 35–55 mm, and D and α Scope and l Commonly limited.

[0050] In this embodiment, as Figure 5 As shown, the multi-objective optimization method includes model building and validation, central aperture shape selection, sample generation, surrogate model training, multi-objective optimization, and back-substitution validation.

[0051] After determining the circular center through hole, use the side length of the plate l and the diameter of the center through hole D For design variables, T max Δ T and S Simultaneously, with minimizing as the optimization objective, the following multi-objective optimization problem is established: min F ( l , D )=[ T max ( l , D ), Δ T ( l , D ), S ( l , D The constraint condition is 35 mm ≤ l ≤55 mm, 0 mm≤ D ≤30 mm and 1 / 6≤ D / l ≤2 / 3.

[0052] Within the aforementioned design space, 52 sets of sample points were generated using Latin hypercube sampling; for each set of sample points, a validated lithium-ion battery air-cooled CFD model was called to obtain the corresponding... T max Δ T and S The design variables and their performance responses are then used to form a training sample set.

[0053] Specifically for T max Δ T and S The Kriging surrogate model was trained, and the prediction accuracy was evaluated using mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R²). The evaluation results of the surrogate model are shown in Table 3.

[0054] Table 3 Prediction accuracy of the Kriging surrogate model

[0055] In Table 3, the R² values ​​for the three objectives are all greater than 0.95, and the MAE and RMSE are both at low levels, indicating that the Kriging surrogate model can accurately characterize the mapping relationship between design variables and thermal performance indicators.

[0056] The above multi-objective optimization problem was solved using NSGA-II, with a population size of 100, a maximum number of iterations of 500, and a crossover probability of 0.8, yielding 100 Pareto optimal solutions. Based on a comprehensive trade-off of three temperature parameters, the plate side length was selected from the Pareto optimal solution set. l =43.10 mm, diameter of the center through hole D =17.10 mm design scheme, corresponding D / l =0.397.

[0057] In this embodiment, the optimization results are verified as follows: Will l =43.10 mm D The candidate scheme with a diameter of 17.10 mm was substituted back into the lithium-ion battery air-cooled CFD model for recalculation. The surrogate model prediction results, CFD recalculation results, and the results of the original air-cooled system without the central through-hole guide plate are shown in Table 4.

[0058] Table 4 Performance and Validation Results of the Optimization Scheme

[0059] As shown in Table 4, the maximum relative error between the surrogate model and the CFD recalculation results is 1.40%, indicating that the optimized process has good prediction accuracy. Compared with the original system, the optimized scheme significantly reduces the highest temperature, maximum temperature difference, and temperature standard deviation.

[0060] like Figure 4 As shown, without the central through-hole guide plate, the incoming airflow is mainly concentrated in the central area of ​​the battery module 4 and flows directly to the air outlet 3. After the central through-hole guide plate 5 is installed, part of the airflow is retained in the central area through the central through-hole 52, while the other part of the airflow is distributed to the outer periphery along the plate 51 and enters the peripheral cooling channel 43. Thus, the central through-path 6 and the outer peripheral flow path 7 jointly regulate the cooling airflow in the central and peripheral areas, making the temperature distribution of each cylindrical cell 41 in the battery module 4 more uniform.

[0061] Therefore, it can be seen that the present invention can coordinate the cooling airflow in the middle and peripheral areas of the battery module, reduce the maximum temperature and improve temperature uniformity.

[0062] If this invention discloses or relates to components or structural parts that are fixedly connected to each other, then, unless otherwise stated, a fixed connection can be understood as: a fixed connection that can be detached (e.g., using bolts or screws), or a fixed connection that cannot be detached (e.g., riveting, welding). Of course, a fixed connection can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0063] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0064] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A lithium-ion battery air-cooled thermal management system, comprising a battery box containing battery modules, the battery box having a first wall and a second wall disposed opposite to each other, the first wall having an air inlet, and the second wall having an air outlet corresponding to the position of the air inlet; the battery module comprising a plurality of spaced cylindrical cells, with a central cooling channel formed between adjacent cylindrical cells, and an outer cooling channel formed between the outer periphery of the battery module and the side wall of the battery box; characterized in that: A guide plate is arranged parallel to the air inlet and the battery module. A central through hole is opened in the central area of ​​the guide plate. The central through hole corresponds to and is connected to the air inlet and the central cooling channel. The outer edge of the guide plate is spaced apart from the side wall of the battery box, and the spaced area forms an outer flow gap. The outer flow gap is connected to the outer cooling channel.

2. The lithium-ion battery air-cooled thermal management system according to claim 1, characterized in that: The axes of the air inlet, the central through hole, and the air outlet coincide; the projection of the central through hole onto the battery module is located in the central region of the battery module.

3. The lithium-ion battery air-cooled thermal management system according to claim 1, characterized in that: The outer edges of each side of the guide plate form an external flow gap with the adjacent battery box sidewall.

4. The lithium-ion battery air-cooled thermal management system according to claim 1, characterized in that: The guide plate is a square flat plate, and the side length of the guide plate is... l The diameter of the central through hole is D 35 mm≤ l ≤55 mm, 5 mm≤ D ≤30mm, and 1 / 6≤ D / l ≤2 / 3.

5. A lithium-ion battery air-cooled thermal management system according to claim 4, characterized in that: 40 mm≤ l ≤50mm, 14 mm≤ D ≤22 mm, and 0.30≤ D / l ≤0.

50.

6. A lithium-ion battery air-cooled thermal management system according to claim 1, characterized in that: The central through hole is a circular through hole.

7. A lithium-ion battery air-cooled thermal management system according to claim 1, characterized in that: The first wall is located at the top of the battery box, and the second wall is located at the bottom of the battery box; the guide plate is parallel to the first wall, and the distance between the surface of the guide plate facing the battery module and the top surface of the cylindrical cell is 1 to 3 mm.

8. A multi-objective optimization method for a lithium-ion battery air-cooled thermal management system as described in any one of claims 1 to 7, characterized in that: Includes the following steps: Step S1: Obtain the structural parameters, thermal properties, and operating parameters of the battery box, battery module, air guide plate, and air, and establish a CFD model for the air-cooled thermal management of lithium-ion batteries; Step S2: Perform a grid independence test on the CFD model of air-cooled thermal management of lithium-ion battery established in step S1, and verify the model using cell temperature data at at least two discharge rates. Step S3: Under the condition that the central through-hole area is the same, compare at least two central through-hole shapes, and determine the central through-hole shape according to the highest temperature and the maximum temperature difference of the battery module; Step S4: Using the side length of the deflector l Equivalent diameter of the center through hole D As design variables, sample points are generated within a preset design space, and the highest temperature corresponding to each sample point is calculated using a CFD model of lithium-ion battery air-cooled thermal management. T max Maximum temperature difference Δ T and temperature standard deviation S ; Step S5: Based on the sample points generated in step S4 and their corresponding... T max Δ T and S Training the Kriging agent model; Step S6: with T max Δ T and S Simultaneously, with the minimum as the optimization objective, a Pareto optimal solution set is obtained using a non-dominated sorting genetic algorithm based on the Kriging surrogate model; Step S7: Select candidate design schemes from the Pareto optimal solution set, and substitute the candidate design schemes back into the lithium-ion battery air-cooling thermal management CFD model for verification to determine the final design scheme.

9. The multi-objective optimization method for a lithium-ion battery air-cooled thermal management system according to claim 8, characterized in that: In step S3, the central through-holes of circles, squares, and equilateral triangles are compared, and it is determined that the central through-hole is circular. In step S4, Latin hypercube sampling is used to generate 52 sets of sample points, and 35 mm ≤ l ≤55 mm, 0 mm≤ D ≤30 mm, 1 / 6≤ D / l ≤2 / 3.

10. The multi-objective optimization method for a lithium-ion battery air-cooled thermal management system according to claim 8, characterized in that: In step S5, the coefficient of determination R², mean absolute error (MAE), and root mean square error (RMSE) are used to evaluate the Kriging surrogate model. T max Δ T and S The corresponding R² values ​​are all greater than 0.95; in step S6, the non-dominated sorting genetic algorithm is NSGA-II, the population size is 100, the maximum number of iterations is 500, and the crossover probability is 0.8.

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