A power battery thermal management system with a large flat heat pipe coupled with a topology-optimized cold plate

Abstract

The present invention provides a power battery thermal management system featuring a large flat heat pipe coupled with a topology-optimized cold plate, belonging to the technical field of power battery thermal management systems. The system comprises: a battery pack consisting of a plurality of batteries connected in series, a large flat heat pipe group, and a topology-optimized cold plate group; the large flat heat pipe group contacts the battery pack and the topology-optimized cold plate group, respectively, and thermally conductive silicone gaskets are provided between the large flat heat pipe group, the battery pack, and the topology-optimized cold plate group; the contact surface between the large flat heat pipe group and the battery pack forms the evaporation end of the large flat heat pipe group, while the contact surface between the large flat heat pipe group and the topology-optimized cold plate group forms the condensation end of the large flat heat pipe group, and the large flat heat pipe group does not have an insulating end. The present invention achieves efficient heat dissipation, ensures that the battery pack temperature remains stable within a reasonable range, reduces battery pack temperature differences, and improves battery pack consistency; it also improves space utilization, reduces system power consumption and voltage drop, and enhances the overall performance and safety of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery thermal management systems, and in particular to a power battery thermal management system with a large flat heat pipe coupled to a topology-optimized cold plate. Background Art

[0002] With the widespread adoption of electric vehicles and the rapid development of energy storage power stations, battery performance is directly related to the safety and range of electric vehicles and the stability of energy storage power stations. The ideal operating temperature range for batteries is 25°C-40°C, and the temperature difference within the battery pack must be controlled within a range of no more than 5°C. When the temperature drops below -40°C, the battery's internal resistance increases, the reaction speed slows, and normal charging cannot be achieved. Excessive temperatures can easily cause thermal runaway, seriously threatening battery safety. Furthermore, temperature differences can lead to poor battery pack consistency, potentially causing some individual cells to overcharge or over-discharge, significantly impacting the overall performance and service life of the battery pack.

[0003] Currently, common battery thermal management technologies include air cooling, liquid cooling, and phase change material (PCM) cooling. Although air cooling technology has a simple structure, due to the limited heat transfer capacity of air, it has problems such as slow heat exchange and large temperature differences between inlet and outlet, making it difficult to meet the needs of efficient heat dissipation and gradually being replaced by other technologies. Although liquid cooling technology has a high heat exchange efficiency, current research focuses on microchannels, optimized flow channel structure, improved control strategies, and the use of nanofluids and other heat transfer enhancement methods, but liquid cooling plates have the safety hazard of leakage. PCM has the advantages of low cost, high latent heat, and non-corrosiveness. However, it is a passive heat transfer method and usually needs to be used in conjunction with other cooling methods. This may result in a large space occupation and there is a risk of leakage during the melting process.

[0004] Therefore, there is an urgent need for a more efficient, safe and space-efficient power battery thermal management system to solve the technical problems existing in the existing technology. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a power battery thermal management system with a large flat heat pipe coupled with a topology-optimized cold plate, which can achieve efficient heat dissipation, ensure that the battery pack temperature is stable within a reasonable range, reduce the temperature difference of the battery pack, and improve the consistency of the battery pack; at the same time, it improves space utilization, reduces system power consumption and voltage drop, and improves the overall performance and safety of the battery.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A power battery thermal management system with a large flat heat pipe coupled with a topology-optimized cold plate, wherein the power battery heat pipe system has an overall symmetrical structure and includes:

[0008] A battery pack consisting of several 70Ah ternary lithium batteries connected in series;

[0009] A large flat heat pipe group, wherein the inner wall of the large flat heat pipe group contacts the outer wall of the battery pack, and a thermally conductive silicone gasket is provided on the contact surface between the large flat heat pipe group and the battery pack;

[0010] A topology optimized cold plate group, wherein the topology optimized cold plate group contacts the large flat plate heat pipe group, and a thermally conductive silicone gasket is provided on the contact surface between the topology optimized cold plate group and the large flat plate heat pipe group;

[0011] The contact surface between the large flat heat pipe group and the battery group is the evaporation end of the large flat heat pipe group, and the contact surface between the large flat heat pipe group and the topology optimized cold plate group is the condensation end of the large flat heat pipe group, and the large flat heat pipe group is not provided with an insulating end.

[0012] Preferably, the large flat heat pipe group consists of a first flat heat pipe and a second flat heat pipe, which are symmetrically arranged. The first flat heat pipe is arranged on one side of the battery pack, and the second flat heat pipe is arranged on the other side of the battery pack. The first flat heat pipe and the second flat heat pipe are both provided with a liquid wick, a support column and a fixing structure. The support column is used to enhance the structural strength of the large flat heat pipe group, and the fixing structure is used to stabilize the liquid wick.

[0013] Preferably, the preparation process of the liquid absorbent core is: selecting a core material after chemical oxidation as the material of the liquid absorbent core, then placing the liquid absorbent core at 200°C and in a reducing environment containing hydrogen or ammonia for 2 hours, so that a firm oxidation layer of several strip-shaped worm aggregates is formed on the skeleton surface of the liquid absorbent core, and the size of the strip-shaped worm aggregates is 10μm~20μm.

[0014] Preferably, the topology optimized cold plate group consists of a first topology optimized liquid cooling plate and a second topology optimized liquid cooling plate, the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate are symmetrically arranged, and the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate are respectively in contact with the condensing ends of the corresponding flat plate heat pipes.

[0015] Preferably, the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate have the same structure, the outlet of the first topology optimized liquid cooling plate and the outlet of the second topology optimized liquid cooling plate are both arranged at the bottom end of the corresponding liquid cooling plate, and the inlet of the first topology optimized liquid cooling plate and the inlet of the second topology optimized liquid cooling plate are both arranged at the top of the opposite surface of the corresponding outlet or on the same side of the corresponding outlet.

[0016] Preferably, the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate are both prepared by topology optimization, and the specific process is as follows:

[0017] First, the variable density method is used to introduce virtual materials of different densities into the design domain of the liquid cooling plate. By adjusting the density value of the virtual material γ , change the regional flow resistance to optimize the flow path of the fluid in the liquid cooling plate and improve the heat dissipation efficiency, where 0≤ γ ≤1; the composite objective function obtained by weighted summation of the heat transfer performance index of the liquid cooling plate and the fluid power dissipation index is used as the optimization target; wherein the composite objective function is:

[0018] ;

[0019] Where, J is the composite objective function, and are the initial values ​​of fluid power dissipation and heat transfer performance indicators, is the weight factor, ranging from 0 to 1;

[0020] in, is the fluid power dissipation index, and the calculation formula is:

[0021] ;

[0022] in, μ is the viscosity, u is the fluid velocity; α ( γ ) is the reverse permeation rate, and the calculation formula is:

[0023] ;

[0024] Where, q is the penalty factor, and are the reverse osmosis rates of solids and fluids, respectively;

[0025] is the heat transfer performance index, and the calculation formula is:

[0026] ;

[0027] in, T is the design domain unit temperature, is the density value, is the design domain area;

[0028] Next, set the volume fraction is the constraint condition for topology optimization, which represents the maximum proportion of the fluid area in the entire liquid cooling plate and meets the requirements:

[0029] ;

[0030] The optimal value of the volume fraction is determined through multiple simulations and experiments;

[0031] Next, determine the weight factor The optimal value of , balances the emphasis of heat transfer performance index and fluid power dissipation index in the composite objective function to achieve comprehensive performance optimization of the liquid cooling plate;

[0032] Finally, the composite objective function is iteratively calculated, and the density value of the virtual material is continuously adjusted during the iteration process to determine the minimum value of the composite objective function:

[0033] ;

[0034] Where, is the minimum value of the composite objective function, which is used to achieve structural optimization of the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate.

[0035] Preferably, the volume fraction is the maximum proportion of the fluid area in the entire liquid cooling plate, and the optimal value of the volume fraction is determined by numerical simulation and experimental research, specifically: first, a numerical simulation is performed, and a liquid cooling plate model is established using finite element analysis software, different volume fractions are set, and the flow channel pressure distribution, coolant flow rate, and battery pack average temperature are simulated and recorded; then, an experimental study is performed to manufacture liquid cooling plate specimens with flow channels of different volume fractions, and the specimens are tested under simulated power battery charging and discharging conditions to monitor the coolant flow rate, pressure loss, and battery pack temperature changes; finally, the numerical simulation results and the experimental research results are combined. When the volume fraction is 0.5, the overall average temperature of the liquid cooling plate reaches the minimum value, so the optimal value of the volume fraction is determined to be 0.5.

[0036] Preferably, the weight factor is the proportion of the heat exchange performance index and the fluid power dissipation index in the composite objective function. The optimal value of the weight factor is determined by combining simulation and experiment, specifically: first, a simulation is performed, using software to simulate the performance of the liquid cooling plate under different weight factors, and recording the data of the average temperature of the battery pack and the pressure drop of the liquid cooling plate; then an experiment is performed to produce liquid cooling plate prototypes with different weight factors, and test them in a simulated power battery working environment, monitoring the battery pack temperature, coolant flow and pressure changes; finally, the simulation data and experimental data are combined. When the weight factor is 0.6, the pressure drop change tends to be stable. When the weight factor is 0.75, the average temperature of the battery pack reaches the minimum value, so the optimal value of the weight factor is 0.75.

[0037] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0038] (1) The present invention uses a large flat heat pipe group and a topology-optimized cold plate group to quickly conduct and dissipate the heat generated by the battery pack, effectively reducing the average and maximum temperatures of the battery pack. Compared with a traditional straight-channel cold plate, the topology-optimized optimal cold plate of the present invention can reduce the average temperature of the battery by 4.52°C and the maximum temperature by 4.63°C at a flow rate of 0.15m / s, greatly improving the temperature uniformity of the battery pack and reducing the battery performance degradation caused by temperature differences.

[0039] (2) This invention uses topology optimization to optimize the liquid cooling plate flow path, effectively reducing the system pressure drop. At a flow rate of 0.15 m / s, the pressure drop is reduced by 30.28% compared to the traditional straight-channel liquid cooling plate. While ensuring that the maximum battery temperature does not exceed 40°C, the required pressure drop is reduced by 77.36% compared to the traditional straight-channel liquid cooling plate, reducing system operating power consumption and improving energy efficiency.

[0040] (3) The large flat heat pipe group and battery pack of the present invention adopt a staggered layout structure. Compared with the conventional method of attaching heat pipes between two batteries, the overall thermal management system structure is more compact and effectively improves space utilization. At the same time, the coupling design of the large flat heat pipe group and the topology-optimized liquid cooling plate group further optimizes the system structure and achieves more efficient heat dissipation function within a limited space.

[0041] (4) The support columns within the large flat plate heat pipe assembly of the present invention enhance structural strength, and the fixed structure stabilizes the liquid wick, ensuring reliable operation of the large flat plate heat pipe assembly under complex working conditions. The specially treated liquid wick enhances capillary force, ensuring smooth circulation of the working fluid. In addition, the leakage problem that may occur when the topology optimized liquid cooling plate assembly is used alone is avoided, thereby improving the reliability and safety of the entire thermal management system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A schematic diagram of the overall structure provided in Example 1 of the present invention;

[0044] Figure 2 A schematic structural diagram of a large flat heat pipe assembly provided in Example 1 of the present invention;

[0045] Figure 3 A schematic diagram of the structure of a topology optimized liquid cooling plate assembly provided in Example 1 of the present invention;

[0046] Figure 4 Schematic diagram of two liquid cooling plate structures provided in Example 1 of the present invention; wherein, Figure 4 (a) is the schematic diagram of the b7 cold plate structure. Figure 4 (b) is a schematic diagram of the straight cold plate structure;

[0047] Figure 5 Two battery pack temperature cloud maps provided in Example 1 of the present invention; wherein, Figure 5 (a) is the temperature cloud diagram of the battery pack under the straight cold plate. Figure 5 (b) is the temperature cloud of the battery pack under the b7 cold plate;

[0048] Figure 6 Another overall structural diagram provided for embodiment 2 of the present invention;

[0049] Figure 7 This is a schematic structural diagram of another topology optimized liquid cooling plate group provided in Example 2 of the present invention.

[0050] Reference numerals:

[0051] 1. Battery pack; 2. Large flat heat pipe group; 21. First flat heat pipe; 22. Second flat heat pipe; 3. Topology optimized cold plate group; 31. First topology optimized liquid cold plate; 32. Second topology optimized liquid cold plate; 4. Upper cover; 5. Liquid wick; 6. Liquid filling port; 7. Support column; 8. Bottom plate; 9. Inlet; 10. Outlet. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] Example 1

[0055] like Figure 1 As shown, the present invention provides a power battery thermal management system with a large flat heat pipe coupled with a topology-optimized cold plate. The power battery heat pipe system has an overall symmetrical structure, including:

[0056] A battery pack 1 is composed of several 70Ah ternary lithium batteries connected in series. In this embodiment, 12 ternary lithium batteries are used. The battery pack 1 is numbered as Battery I, Battery II, Battery III, Battery IV, Battery V, Battery VI, Battery VII, Battery VIII, Battery IX, Battery X, Battery XI, and Battery XII, depending on the left and right sides and the battery position.

[0057] A large flat heat pipe group 2, the inner wall of the large flat heat pipe group 2 contacts the outer wall of the battery group 1, and a thermally conductive silicone gasket is provided on the contact surface between the large flat heat pipe group 2 and the battery group 1;

[0058] A topology optimized cold plate group 3, the topology optimized cold plate group 3 is in contact with the large flat plate heat pipe group 2, and a thermally conductive silicone gasket is provided on the contact surface between the topology optimized cold plate group 3 and the large flat plate heat pipe group 2;

[0059] The contact surface between the large flat heat pipe group 2 and the battery group 1 is the evaporation end of the large flat heat pipe group 2, and the contact surface between the large flat heat pipe group 2 and the topology optimized cold plate group 3 is the condensation end of the large flat heat pipe group 2, and the large flat heat pipe group 2 is not provided with an insulating end.

[0060] The large flat heat pipe group 2 and the battery pack 1 are arranged in a staggered manner to improve the space utilization of the entire system. The large flat heat pipe group 2 consists of a first flat heat pipe 21 and a second flat heat pipe 22. The first flat heat pipe 21 and the second flat heat pipe 22 are symmetrically arranged. The first flat heat pipe 21 is arranged on one side of the battery pack 1, and the second flat heat pipe 22 is arranged on the other side of the battery pack 1. Figure 2 The first flat plate heat pipe 21 and the second flat plate heat pipe 22 are each internally provided with a liquid wick 5, a support column 7, and a fixing structure. The support column 7 is used to enhance the structural strength of the large flat plate heat pipe assembly 2, and the fixing structure is used to stabilize the liquid wick 5. Furthermore, the large flat plate heat pipe assembly 2 includes an upper cover plate 4 and a bottom plate 8. The support column 7 is disposed on the inner side of the bottom plate 8, and a liquid injection port 6 is provided at one end of the bottom plate 8. The upper cover plate 4 is disposed above the liquid wick 5.

[0061] Secondly, the preparation process of the above-mentioned wick 5 is as follows: a chemically oxidized core material is selected as the material of the wick, and then the wick 5 is placed in a reducing environment containing hydrogen or ammonia at 200°C for 2 hours to form a strong oxide layer of several strip-shaped worm aggregates on the skeleton surface of the wick 5. The size of the strip-shaped worm aggregates is 10μm~20μm.

[0062] In this embodiment, the topology optimized cold plate group 3 is composed of a first topology optimized liquid cold plate 31 and a second topology optimized liquid cold plate 32. The first topology optimized liquid cold plate 31 and the second topology optimized liquid cold plate 32 are symmetrically arranged, and the first topology optimized liquid cold plate 31 and the second topology optimized liquid cold plate 32 are respectively in contact with the condensing end of the corresponding flat heat pipe. The first topology optimized liquid cold plate 31 and the second topology optimized liquid cold plate 32 have the same structure. Figure 3 The outlet 10 of the first topology optimized liquid cooling plate 31 and the outlet 10 of the second topology optimized liquid cooling plate 32 are both arranged at the bottom end of the corresponding liquid cooling plate, and the inlet 9 of the first topology optimized liquid cooling plate 31 and the inlet 9 of the second topology optimized liquid cooling plate 32 are both arranged at the top opposite to the corresponding outlet 10.

[0063] The first topology optimized liquid cooling plate 31 and the second topology optimized liquid cooling plate 32 are both prepared by topology optimization, and the specific process is as follows:

[0064] First, the variable density method is used to introduce virtual materials of different densities into the design domain of the liquid cooling plate. By adjusting the density value of the virtual material γ , change the regional flow resistance to optimize the flow path of the fluid in the liquid cooling plate and improve the heat dissipation efficiency, where 0≤ γ ≤1; the composite objective function obtained by weighted summation of the heat transfer performance index of the liquid cooling plate and the fluid power dissipation index is used as the optimization target; wherein the composite objective function is:

[0065] ;

[0066] Where, J is the composite objective function, and are the initial values ​​of fluid power dissipation and heat transfer performance indicators, is the weight factor, ranging from 0 to 1;

[0067] in, is the fluid power dissipation index, and the calculation formula is:

[0068] ;

[0069] in, μ is the viscosity, u is the fluid velocity; α ( γ ) is the reverse permeation rate, and the calculation formula is:

[0070] ;

[0071] Where, q is the penalty factor, which is 0.02 in this embodiment. and are the reverse osmosis rates of solid and fluid respectively; when =0, ; Da is the Darcy number, which is 0.0001, and Re is the Reynolds number, which is calculated from the inlet flow velocity.

[0072] is the heat transfer performance index, and the calculation formula is:

[0073] ;

[0074] in, T is the design domain unit temperature, γ is the density value, is the design domain area;

[0075] Next, set the volume fraction is the constraint condition for topology optimization, which represents the maximum proportion of the fluid area in the entire liquid cooling plate and meets the requirements:

[0076] ;

[0077] The optimal value of the volume fraction is determined through multiple simulations and experiments;

[0078] Next, determine the weight factor The optimal value of , balances the emphasis of heat transfer performance index and fluid power dissipation index in the composite objective function to achieve comprehensive performance optimization of the liquid cooling plate;

[0079] Finally, the composite objective function is iteratively calculated, and the density value of the virtual material is continuously adjusted during the iteration process to determine the minimum value of the composite objective function:

[0080] ;

[0081] Where, is the minimum value of the composite objective function, which is used to achieve structural optimization of the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate.

[0082] In the above content, the volume fraction is the maximum proportion of the fluid area in the entire liquid cooling plate. The larger the volume fraction, the thicker the flow channel and the smaller the pressure drop, but the overall average temperature first decreases and then increases; the optimal value of the volume fraction is determined by numerical simulation and experimental research, specifically: first, numerical simulation is performed, and a liquid cooling plate model is established using finite element analysis software. Different volume fractions are set to simulate and record the flow channel pressure distribution, coolant flow rate, and battery pack average temperature; then, experimental research is performed to manufacture liquid cooling plate specimens with different volume fraction flow channels, and the specimens are tested under simulated power battery charge and discharge conditions to monitor coolant flow, pressure loss, and battery pack temperature changes; finally, the numerical simulation results and experimental research results are combined. When the volume fraction is 0.5, the overall average temperature of the liquid cooling plate reaches the minimum value, so the optimal value of the volume fraction is determined to be 0.5. Reference Figure 4 (a) and Figure 4 (b) in the figure provides the structural schematic diagrams of the b7 cold plate and the straight cold plate respectively. Then, under the same working conditions, the heat dissipation effect of the battery pack of the two cold plates is intuitively demonstrated. The results are as follows Figure 5 (a) and Figure 5 As shown in (b) in the figure. Figure 5 In (a), the battery pack temperature distribution is relatively uneven, with a large proportion of high-temperature areas, indicating that the heat dissipation effect of the battery pack under the straight cold plate is limited. Figure 5 In (b), the overall temperature of the battery pack has decreased, the color distribution has become more uniform, and the area of ​​the high-temperature area has been significantly reduced. This shows that the b7 cold plate is the optimal topology optimized liquid cold plate. At a flow rate of 0.15m / s, its maximum temperature is 4.63°C lower than that of the traditional straight cold plate, the average temperature is 4.52°C lower, and the pressure drop is reduced by 30.82%.

[0083] The weight factor is the proportion of the heat exchange performance index and the fluid power dissipation index in the composite objective function. The larger the value of the weight factor, the stronger the heat exchange performance in the composite objective function, but the pressure drop of the liquid cooling plate gradually increases; the smaller the value of the weight factor, the greater the proportion of the fluid power dissipation index in the composite function, and the flow channel design is relatively simple; the optimal value of the weight factor is determined by combining simulation and experiment, specifically: first, a simulation is performed, using software to simulate the performance of the liquid cooling plate under different weight factors, and recording the data of the average temperature of the battery pack and the pressure drop of the liquid cooling plate; then an experiment is conducted to make liquid cooling plate prototypes with different weight factors, test them in a simulated power battery working environment, and monitor the changes in battery pack temperature, coolant flow and pressure; finally, combining the simulation data and experimental data, when the weight factor is 0.6, the pressure drop change tends to be stable, and when the weight factor is 0.75, the average temperature of the battery pack reaches the minimum value, so the optimal value of the weight factor is 0.75.

[0084] Working Principle: During high-rate discharge, the generated heat is rapidly transferred symmetrically to the condenser end of the large flat heat pipe assembly 2. Because the condenser end fits snugly against the topology-optimized cold plate assembly 3 and a high-thermal-conductivity silicone thermal gasket is added to the interface, the heat is smoothly transferred to the low-temperature working fluid in the liquid cold plate. The low-temperature working fluid then removes the heat through a circulation system, effectively cooling the battery pack 1. This ensures that the power battery maintains excellent temperature uniformity and rapid response, ensuring efficient and safe operation.

[0085] Example 2

[0086] like Figure 6 As shown, this embodiment also provides a power battery thermal management system with a large flat heat pipe coupled with a topology optimized cold plate, which is different from the first embodiment in that: Figure 7 The outlet 10 of the first topology optimized liquid cooling plate 31 and the outlet 10 of the second topology optimized liquid cooling plate 32 are both arranged at the bottom end of the corresponding liquid cooling plate, and the inlet 9 of the first topology optimized liquid cooling plate 31 and the inlet 9 of the second topology optimized liquid cooling plate 32 are both arranged on the same side of the corresponding outlet 10, and the rest are the same as in Example 1.

[0087] Therefore, the power battery thermal management system using the above-mentioned large flat heat pipe coupled topology optimized cold plate can achieve efficient heat dissipation, ensure that the battery pack temperature is stable within a reasonable range, reduce the temperature difference of the battery pack, and improve the consistency of the battery pack; at the same time, it improves space utilization, reduces system power consumption and voltage drop, and improves the overall performance and safety of the battery.

[0088] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0089] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A power battery thermal management system with a large flat heat pipe coupled with a topology optimized cold plate, characterized in that: The power battery thermal management system has an overall symmetrical structure, including: A battery pack consisting of several batteries connected in series; A large flat heat pipe group, wherein the inner wall of the large flat heat pipe group contacts the outer wall of the battery pack, and a thermally conductive silicone gasket is provided on the contact surface between the large flat heat pipe group and the battery pack; A topology optimized cold plate group, wherein the topology optimized cold plate group contacts the large flat plate heat pipe group, and a thermally conductive silicone gasket is provided on the contact surface between the topology optimized cold plate group and the large flat plate heat pipe group; The contact surface between the large flat heat pipe group and the battery group is the evaporation end of the large flat heat pipe group, and the contact surface between the large flat heat pipe group and the topology optimized cold plate group is the condensation end of the large flat heat pipe group, and the large flat heat pipe group is not provided with an insulating end; The large flat heat pipe group consists of a first flat heat pipe and a second flat heat pipe, which are symmetrically arranged. The first flat heat pipe is arranged on one side of the battery pack, and the second flat heat pipe is arranged on the other side of the battery pack. The first flat heat pipe and the second flat heat pipe are each provided with a liquid wick, a support column and a fixing structure. The support column is used to enhance the structural strength of the large flat heat pipe group, and the fixing structure is used to stabilize the liquid wick. The topology optimized cold plate group consists of a first topology optimized liquid cooling plate and a second topology optimized liquid cooling plate, the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate are symmetrically arranged, and the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate are respectively in contact with the condensation end of the corresponding flat heat pipe; the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate have the same structure, the outlet of the first topology optimized liquid cooling plate and the outlet of the second topology optimized liquid cooling plate are both arranged at the bottom end of the corresponding liquid cooling plate, and the inlet of the first topology optimized liquid cooling plate and the inlet of the second topology optimized liquid cooling plate are both arranged at the top of the opposite surface of the corresponding outlet or on the same side of the corresponding outlet.

2. The power battery thermal management system of a large flat heat pipe coupled with a topology optimized cold plate according to claim 1, characterized in that: The preparation process of the liquid absorbent core is as follows: a chemically oxidized core material is selected as the material of the liquid absorbent core, and then the liquid absorbent core is placed in a reducing environment containing hydrogen or ammonia at 200°C for 2 hours to form a firm oxidation layer of a plurality of strip-shaped worm aggregates on the skeleton surface of the liquid absorbent core. The size of the strip-shaped worm aggregates is 10μm~20μm.

3. The power battery thermal management system of a large flat heat pipe coupled with a topology optimized cold plate according to claim 1, characterized in that: The first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate are both prepared by topology optimization, and the specific process is as follows: First, the variable density method is used to introduce virtual materials of different densities into the design domain of the liquid cooling plate. By adjusting the density value of the virtual material γ , change the regional flow resistance to optimize the flow path of the fluid in the liquid cooling plate and improve the heat dissipation efficiency, where 0≤ γ ≤1; the composite objective function obtained by weighted summation of the heat transfer performance index of the liquid cooling plate and the fluid power dissipation index is used as the optimization target; wherein the composite objective function is: ； Where, J is the composite objective function, and are the initial values ​​of fluid power dissipation and heat transfer performance indicators, is the weight factor, ranging from 0 to 1; in, is the fluid power dissipation index, and the calculation formula is: ； in, μ is the viscosity, u is the fluid velocity; α ( γ ) is the reverse permeation rate, and the calculation formula is: ； Where, q is the penalty factor, and are the reverse osmosis rates of solids and fluids, respectively; is the heat transfer performance index, and the calculation formula is: ； in, T is the design domain unit temperature, γ is the density value, is the design domain area; Next, set the volume fraction is the constraint condition for topology optimization, which represents the maximum proportion of the fluid area in the entire liquid cooling plate and meets the requirements: ； The optimal value of the volume fraction is determined through multiple simulations and experiments; Next, determine the weight factor The optimal value of , balances the emphasis of heat transfer performance index and fluid power dissipation index in the composite objective function to achieve comprehensive performance optimization of the liquid cooling plate; Finally, the composite objective function is iteratively calculated, and the density value of the virtual material is continuously adjusted during the iteration process to determine the minimum value of the composite objective function: ； Where, is the minimum value of the composite objective function, which is used to achieve structural optimization of the first topology optimized liquid cooling plate and the second topology optimized liquid cooling plate.

4. The power battery thermal management system of a large flat heat pipe coupled with a topology optimized cold plate according to claim 3, characterized in that: The volume fraction is the maximum proportion of the fluid area in the entire liquid cooling plate. The optimal value of the volume fraction is determined through numerical simulation and experimental research. Specifically, numerical simulation is first performed, and a liquid cooling plate model is established using finite element analysis software. Different volume fractions are set, and the flow channel pressure distribution, coolant flow rate, and battery pack average temperature are simulated and recorded; then, experimental research is performed to manufacture liquid cooling plate specimens with flow channels of different volume fractions, and the specimens are tested under simulated power battery charging and discharging conditions to monitor the coolant flow rate, pressure loss, and battery pack temperature changes; finally, the numerical simulation results and experimental research results are combined. When the volume fraction is 0.5, the overall average temperature of the liquid cooling plate reaches the minimum value, so the optimal value of the volume fraction is determined to be 0.

5.

5. The power battery thermal management system of a large flat plate heat pipe coupled with a topology optimized cold plate according to claim 3, characterized in that: The weight factor is the proportion of the heat exchange performance index and the fluid power dissipation index in the composite objective function. The optimal value of the weight factor is determined by combining simulation and experiment. Specifically, a simulation is first performed, using software to simulate the performance of the liquid cooling plate under different weight factors, and recording the data of the average temperature of the battery pack and the pressure drop of the liquid cooling plate; then an experiment is conducted to produce liquid cooling plate prototypes with different weight factors, test them in a simulated power battery working environment, and monitor the changes in battery pack temperature, coolant flow and pressure; finally, the simulation data and experimental data are combined. When the weight factor is 0.6, the pressure drop change tends to be stable. When the weight factor is 0.75, the average temperature of the battery pack reaches the minimum value, so the optimal value of the weight factor is 0.75.

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