Nano-fluid tree-root-shaped cold plate for power battery

Abstract

The invention discloses a nanofluid tree-root-imitated cold plate for a power battery, which comprises a battery cold plate, the battery cold plate is arranged at the top of the power battery, a tree-root-imitated sine flow channel is arranged in the battery cold plate, the nanofluid is arranged in the tree-root-imitated sine flow channel, and the nanofluid is arranged in the tree-root-imitated sine flow channel. The root-imitated sinusoidal flow channel comprises a plurality of sinusoidal pipelines which are connected in parallel at equal intervals to provide a flow channel for the nanofluid, and the nanofluid is a mixed nanofluid of copper and water. According to the technical scheme, efficient heat transfer can be performed on the power battery.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal management of power batteries, and in particular relates to a nanofluid tree root-shaped cold plate for power batteries. Background Art

[0002] The power generation section of the new energy industry uses more new forms of power generation energy such as wind energy, solar energy, nuclear energy and hydropower to generate electricity. In the energy utilization section, battery energy storage is used to store the electricity and then reuse it later. As a popular industry in the new energy industry, electric vehicles have become an increasingly popular industry and are also the main industry in the current new energy track. Lithium batteries are widely used as an important battery material energy for electric vehicles. Because of their high energy density, long life cycle, good durability and low price, lithium batteries have become the main source of power. However, the heat transfer efficiency of the battery cold plate corresponding to the existing lithium battery is not high. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a nanofluid tree root-shaped cold plate for a power battery to solve the above problems in the prior art.

[0004] To achieve the above object, the present invention provides a nanofluid tree root-shaped cold plate for a power battery, comprising:

[0005] A battery cold plate, wherein the battery cold plate is arranged on the top of the power battery, wherein a tree root-like sinusoidal flow channel is arranged inside the battery cold plate, wherein the tree root-like sinusoidal flow channel is provided with a nanofluid, wherein the tree root-like sinusoidal flow channel comprises a plurality of sinusoidal pipes connected in parallel at equal intervals to provide a flow channel for the nanofluid, and the nanofluid is a mixed nanofluid of copper and water.

[0006] Optionally, the nanofluid is a mixed nanofluid of copper and water with a volume fraction of 5%.

[0007] Optionally, a heating device is also provided on the battery cold plate.

[0008] Optionally, both ends of the plurality of sinusoidal pipes are respectively connected to the coolant outlet and the coolant inlet through pipes.

[0009] Optionally, the battery cold plate and the tree root-like sinusoidal flow channel are both made of aluminum.

[0010] Optionally, relevant parameters of the battery cold plate are adjusted, a numerical simulation analysis is performed on the battery cold plate, and optimization results of the relevant parameters are obtained according to the numerical simulation analysis results; wherein the relevant parameters include the type, initial velocity, initial temperature and volume fraction of the nanofluid.

[0011] Optionally, the type of the nanofluid is adjusted, and a numerical simulation analysis is performed on the battery cold plate, and the optimal type of the nanofluid is obtained according to the numerical simulation analysis result of the type of the nanofluid.

[0012] Optionally, based on the optimal type of nanofluid and taking the average battery temperature and pressure drop as the target, a battery thermal management model is constructed for the initial velocity, initial temperature and volume fraction of the nanofluid through the response surface method, and the battery thermal management model is optimized and solved through the optimization algorithm to obtain the optimal initial velocity, optimal initial temperature and optimal volume fraction of the nanofluid.

[0013] Optionally, the battery thermal management model is:

[0014] Average battery temperature = -30.54991-30.40219A+1.26107B-0.663197C-0.001005AB

[0015] +0.57495AC+0.001412BC+58.22538A 2 -0.00045B 2 +0.006018C 2

[0016] Pressure drop = 18.3984 + 315.27146A - 0.001015B - 1.67254C + 0.001545AB

[0017] +42.48479AC+0.000112BC+1851.788883A 2 +0B 2 +0.041202C 2

[0018] Wherein, A represents the initial velocity of the nanofluid, B represents the initial temperature of the nanofluid, and C represents the volume fraction of the nanofluid.

[0019] Optionally, the optimization algorithm adopts a non-dominated sorting genetic algorithm.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] Compared with the prior art, the present invention has the following significant advantages: simple structure, convenient processing, and low cost. A tree root-like positive selection pipe flow channel is added between the battery cold plates to strengthen the heat transfer process between the cold and hot fluids and the battery cold plates, so that the heat of the HTF can be quickly transferred to the cold plates. In addition, a mixture of copper and water with a volume fraction of 5% further strengthens the heat transfer of the working fluid, thereby achieving efficient heat transfer among the cold fluid, the hot fluid and the solid-liquid phase change material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0023] Figure 1 A schematic diagram of a tree root-like sinusoidal pipeline nanofluid cold plate according to an embodiment of the present invention;

[0024] Figure 2 A comparison diagram of heat transfer temperature and fluid between a sinusoidal corrugated tube according to an embodiment of the present invention and a traditional straight tube;

[0025] Figure 3 This is a comparison diagram of the battery cold plate temperature cloud diagram of different volume fractions of nanofluids in an embodiment of the present invention;

[0026] Figure 4 A comparison chart of heat transfer data of battery cold plates with nanofluids of different volume fractions according to an embodiment of the present invention;

[0027] Figure 5 A Pareto curve optimized for voltage drop and average battery temperature in an embodiment of the present invention;

[0028] Among them, 1 is the power battery, 2 is the battery cold plate, 3 is the tree root-like sinusoidal flow channel, and 4 is the nanofluid. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0031] The present invention proposes a nanofluid tree root-shaped cold plate for power batteries. In this solution, a battery cold plate 2 for LiFePO4 batteries combined with a bionic tree root-shaped channel is provided, and the heat transfer thereof is optimized by combining nanoparticles and sinusoidal corrugated tubes. Sinusoidal corrugated tubes are a common measure for enhancing heat transfer in the field of heat transfer. By designing sinusoidal pipes, it is found that sinusoidal pipes have a significant improvement in heat transfer compared to straight pipes. Since they enhance the disturbance of the boundary layer, they also enhance the heat transfer area and improve the heat transfer efficiency. Although the pressure drop will be sacrificed, it is generally a relatively excellent heat transfer enhancement solution.

[0032] Specifically, the present invention proposes a battery cold plate with a nanofluid tree root-like channel, including a battery cold plate 2, a tree root-like sinusoidal flow channel 3, and a nanofluid 4. The battery cold plate 2 combined with the nanofluid tree root-like channel is hollow inside to form a nanofluid channel, namely, a tree root-like sinusoidal flow channel 3. The battery cold plate 2 is arranged on the top of the power battery 1 to transfer heat to the power battery 1. A flowing nanofluid 4 is arranged in the tree root-like sinusoidal flow channel 3, and the nanofluid 4 is a nanofluid mixed with copper and water with a volume fraction of 5%. The heat of the power battery 1 is quickly transferred to the tree root-like sinusoidal flow channel 3 through the battery cold plate 2, and the tree root-like sinusoidal flow channel 3 transfers the heat to the nanofluid 4 to form an efficient cold plate heat dissipation system.

[0033] Specifically, the battery cold plate 2 is located on the upper part of the power battery 1 , and the battery cold plate 2 includes a heat exchange device and a heating device, wherein the heat exchange device mainly plays a role of efficient heat transfer through the above-mentioned tree root-like sinusoidal flow channel 3 and the nanofluid 4 .

[0034] The heat exchange device is a coolant heat transfer device, and its specific structure is as follows: a tree root-like sinusoidal flow channel 3 is arranged inside the battery cold plate 2, and the two ends of the tree root-like sinusoidal flow channel 3 are respectively connected with a coolant inlet and a coolant outlet. A flowing nanofluid 4 is arranged in the tree root-like sinusoidal flow channel 3. The nanofluid 4 enters the tree root-like sinusoidal flow channel 3 from the coolant inlet and flows out through the coolant outlet, bringing out the heat energy transferred from the power battery to the battery cold plate, so as to realize heat transfer to the power battery 1.

[0035] Specifically, the flow channel of the battery cold plate 2 is designed as a tree root-like sinusoidal pipe flow channel 3, which includes a plurality of sinusoidal pipes connected in parallel at equal intervals to provide flow space for the nanofluid.

[0036] Specifically, the battery cold plate 2 is made of metal aluminum, and the tree root-like sinusoidal tube flow channel 3 is also made of aluminum. The above materials can be replaced according to actual requirements and performance needs, which will not be described in detail here.

[0037] The heat transfer medium of the tree-root-like sinusoidal tube flow channel 3 arranged in the battery cold plate 2 is a nanofluid 4, and the nanofluid 4 is a nanofluid of copper and water with a volume fraction of 5%.

[0038] It should be noted that in order to improve the working performance of the above-mentioned nanofluid tree root-shaped cold plate and conduct relevant performance tests, the following technical solutions are provided:

[0039] The present invention discloses a battery cold plate 2 based on a nanofluid tree root-like channel, a tree root-like sinusoidal flow channel 3, and a nanofluid 4 as a heat transfer medium. Commercial CFD software is used to perform numerical simulation analysis on the three-dimensional battery cold plate 2, focusing on the heat transfer problem of the sinusoidal pipe under the nanofluid 4 as the heat transfer medium, so as to improve the heat dissipation performance of the LiFePO4 battery. The subsequent technical scheme of the present invention mainly studies the comparative analysis of the sinusoidal pipe and the ordinary pipe, the influence of different types of nanofluids 4, different volume fractions of nanofluids 4, the initial temperature of the nanofluid 4 and the initial velocity of the nanofluid 4 on the fluid heat transfer characteristics of the battery cold plate 2, and optimizes the above-mentioned related parameters through relevant methods.

[0040] The study of the sinusoidal pipe and the DC pipe of the above-mentioned tree root-like sinusoidal flow channel 3 shows that: by comparing and analyzing with the traditional straight pipe, it is found that the highest and lowest temperatures of the sinusoidal pipe have decreased. At the same time, the Nusselt number and the average heat flux density are increased by 3.28% and 22.06% respectively compared with the straight pipe, and its heat transfer characteristics are significantly improved. In addition, the battery temperature requirements are met at each discharge power. By comparing the types and volume fractions of different nanofluids 4 for heat transfer characteristics analysis, it is found that the 5% Cu and water mixed nanofluid has the best heat transfer characteristics. Under different working conditions, the larger the initial velocity of the nanofluid 4, the lower the initial temperature, and the lower the average temperature of the battery cold plate 2. Finally, the response surface method and genetic algorithm are used to optimize the physical properties and initial working conditions of the nanofluid 4 to obtain the relationship between the relevant influencing factors (initial temperature, initial velocity and volume fraction) and the target (average battery temperature and pressure drop). Finally, the optimal solution is optimized to obtain the inlet flow rate, inlet temperature and nanofluid volume fraction values ​​of 0.14m / s, 288.00K and 4.41% respectively.

[0041] Specifically, a nanofluid tree root-like channel battery cold plate includes a battery cold plate 2 arranged on the top of a power battery 1, a tree root-like sinusoidal flow channel 3 arranged in the battery cold plate 2, and a nanofluid 4 as a heat transfer medium flowing inside the tree root-like sinusoidal flow channel 3. The above structure forms an efficient cold plate heat dissipation system.

[0042] like Figure 2 As shown in the figure, it can be seen that the sinusoidal pipe has a significant cooling effect through CFD simulation technology. Figure 2 Comparative analysis of heat transfer data of different cold plates shows that the maximum temperature and average temperature of the sinusoidal pipe are 2.73K and 2.14K lower than the maximum temperature of the straight pipe, respectively. At the same time, when the Nusselt number and average heat flux density reach a steady state in the battery cold plate 2, the sinusoidal pipe increases by 3.28% and 22.06% respectively compared with the straight pipe. This structure can effectively improve the heat transfer efficiency of the battery cold plate 2.

[0043] Furthermore, the fluid in the sinusoidal pipe will increase the disturbance to the boundary layer when passing through the sinusoidal pipe, and many disturbances will appear in the velocity cloud diagram. The sinusoidal pipe also increases its heat transfer area, so the sinusoidal pipe has a significant enhanced heat transfer effect compared to the straight pipe. Of course, while the sinusoidal pipe increases the fluid flow, it also increases the pressure resistance coefficient. Under the same initial fluid velocity and temperature, the pressure drop of the straight pipe is reduced by 11.3Pa compared to the sinusoidal pipe.

[0044] However, in general, the present invention is a solution that mainly enhances heat transfer, and its pressure drop loss is not large, so the present invention selects a sinusoidal pipe as a flow channel model for optimization and improvement. Figure 3 It can also be seen that the temperature of the area with lower grayscale value where the fluid flows at the beginning is lower, and then the temperature of the cold plate battery pack gradually increases, which means that after the fluid absorbs heat, the temperature rises, and its heat transfer capacity decreases, and it cannot take away more heat, which causes the phenomenon that the temperature in the upper half is low and the temperature in the lower half is high. Therefore, more work should be done to consider the uniformity of battery temperature in future research.

[0045] Furthermore, different nanoparticles in the nanofluid 4 have a significant effect on the heat transfer performance of the nanofluid. This is because different nanoparticles have different thermal conductivities. When they are mixed with a fluid, the nanofluid will have different heat transfer coefficients. In order to find the optimal type of nanofluid 4, four types of nanofluids 4 were compared with pure water to compare the heat transfer performance of different nanofluids 4 on BTMS.

[0046] Furthermore, the nanoparticles select a nanofluid 4 composed of pure water, TiO2, Al2O3, CuO and Cu nanoparticles as the heat transfer medium of the cold plate. The volume fraction of the nanofluid 4 is selected to be 5%. From the cold plate temperature cloud map under different nanoparticles, it can be seen that only the nanofluid with 5% Cu has the lowest maximum temperature, and its low temperature area is also the largest. Overall, the temperature of the lower half area is higher than that of the upper half area. According to the data analysis results of the heat transfer characteristics of the battery cold plate with different nanoparticles, it can be more intuitively found that the average temperature and the maximum temperature of the power battery 2 using the nanofluid 4 with 5% Cu are the lowest, which are 0.78K and 0.81K lower than pure water respectively. At the same time, it can be found that the heat transfer capacity is 5% Cu>5% CuO>5% TiO2>5% Al2O3>pure water. This is mainly because the heat transfer coefficient of Cu is the highest, so the nanofluid 4 with 5% Cu has better heat transfer performance, and its heat transfer capacity is in obvious positive proportion to the heat transfer coefficient of the nanoparticles. At the same time, it can be seen from the pressure drop diagram that the pressure drop of the nanofluid 4 with 5% Cu is the highest, which is mainly because the density of Cu is also the largest, which means that more energy is required to transport it. Nevertheless, compared with pure water, the pressure drop of 5% Cu only increases by 10.81 Pa, which is relatively small. Therefore, the nanofluid 4 of this patent selects a mixture of Cu and water.

[0047] Furthermore, the volume fraction of nanofluid 4 is one of the important factors affecting thermal conductivity. This section selects 1% Cu, 2% Cu, 3% Cu, 4% Cu and 5% Cu mixed with water as heat transfer medium. Figure 3 It can be seen that the maximum temperature of the 5% nanofluid is the lowest, and the maximum temperature also decreases. It can be found that the green low-temperature area of ​​5% Cu is the highest. This is mainly because as the volume fraction of nanoparticles increases, its heat transfer coefficient also increases, so the heat transfer capacity of the battery cold plate 2 is also improved. Figure 4 From the data analysis in , it can be seen that when the volume fraction increases from 0 to 5%, the average battery temperature and the maximum battery temperature decrease by 0.78K and 0.81K respectively, and as the volume fraction of nanofluid 4 increases, the battery temperature becomes negatively correlated, but the pressure drop becomes positively correlated. This is mainly because as the volume fraction increases, the viscosity and density of the fluid also increase, which also increases the pressure drop of the battery cold plate 2. This shows that there is a certain game relationship between the pressure drop and the battery temperature, so the subsequent research will focus on multi-objective optimization.

[0048] Furthermore, the response surface methodology is used to optimize the battery cold plate 2 corresponding to the nanofluid 4 in the tree root type sinusoidal flow channel 3 under different parameters, and the initial velocity A (m / s) of the nanofluid 4, the initial temperature B (K) of the nanofluid 4 and the volume fraction C of the nanofluid are obtained when the thermodynamic indicators of the battery thermal management are optimal.

[0049] Average battery temperature = -30.54991-30.40219A+1.26107B-0.663197C-0.001005AB

[0050] +0.57495AC+0.001412BC+58.22538A 2 -0.00045B 2 +0.006018C 2

[0051] Pressure drop = 18.3984 + 315.27146A - 0.001015B - 1.67254C + 0.001545AB

[0052] +42.48479AC+0.000112BC+1851.788883A 2 +0B 2 +0.041202C 2

[0053] Furthermore, since there is a game relationship between the front voltage drop and the average battery temperature under the influence of various influencing factors, there must be an optimal value that satisfies both the low average battery temperature and the small voltage drop loss. Therefore, the formula result is brought into the non-dominated sorting genetic algorithm NSGA-II for multi-objective optimization. Figure 5 The Pareto front diagram obtained by multi-objective optimization using non-dominated sorting genetic algorithm is given. In this study, the average temperature and pressure drop of the battery are selected as the objective function, and the decision variables and their value ranges are the inlet flow rate, i.e. the initial velocity (0.05-0.25m / s), the inlet temperature, i.e. the initial temperature (288-298K), and the volume fraction of nanofluid 4 (1%-5%). Figure 5It can be seen that when the pressure drop increases, the average battery temperature decreases. Point C in the figure is the point with the smallest pressure drop and average battery temperature. The values ​​of the pressure drop and average battery temperature are 38.56Pa and 291.27K, respectively, which are unattainable. Therefore, point O, which is closest to point C on the Pareto front curve, is selected as the optimal solution. The corresponding values ​​of the pressure drop and average battery temperature are 98.57Pa and 292.15K, respectively. At the same time, the values ​​of the inlet flow rate, inlet temperature and volume fraction corresponding to point O are 0.14m / s, 288.00K and 4.41%, respectively. Finally, the optimization results are brought into the Fluent simulation software for verification. The verification shows that the temperature error of the optimization result is only 0.023%, and the pressure drop error is only 0.15%, and the optimization result is significant.

[0054] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: simple structure, convenient processing, low cost, a tree root-like sinusoidal flow channel 3 is arranged inside the battery cold plate 2, which strengthens the heat transfer process between the cold and hot fluids and the battery cold plate 2, so that the heat of the HTF can be quickly transferred to the cold plate, and in addition, a mixture of 5% volume fraction of copper and water is used as a nanofluid to further strengthen the heat transfer of the working fluid. Thus, efficient heat transfer between the cold fluid, the hot fluid and the solid-liquid phase change material is achieved.

[0055] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A nanofluid tree root-shaped cold plate for power batteries, characterized in that: include: A battery cold plate, wherein the battery cold plate is arranged on the top of the power battery, wherein a tree root-like sinusoidal flow channel is arranged inside the battery cold plate, wherein the tree root-like sinusoidal flow channel is provided with a nanofluid, wherein the tree root-like sinusoidal flow channel comprises a plurality of sinusoidal pipes connected in parallel at equal intervals to provide a flow channel for the nanofluid, and the nanofluid is a mixed nanofluid of copper and water.

2. The nanofluid tree root-shaped cold plate according to claim 1, characterized in that: The nanofluid is a mixed nanofluid of copper and water with a volume fraction of 5%.

3. The nanofluid tree root-shaped cold plate according to claim 1, characterized in that: The battery cold plate is also provided with a heating device.

4. The nanofluid tree root-shaped cold plate according to claim 1, characterized in that: The two ends of the plurality of sinusoidal pipes are respectively connected with the coolant outlet and the coolant inlet through pipes.

5. The nanofluid tree root-shaped cold plate according to claim 1, characterized in that: The battery cold plate and the tree root-like sinusoidal flow channel are both made of aluminum.

6. The nanofluid tree root-shaped cold plate according to claim 1, characterized in that: Adjust relevant parameters of the battery cold plate, perform numerical simulation analysis on the battery cold plate, and obtain optimization results of the relevant parameters according to the numerical simulation analysis results; wherein the relevant parameters include the type, initial velocity, initial temperature and volume fraction of the nanofluid.

7. The nanofluid tree root-shaped cold plate according to claim 1, characterized in that: The type of the nanofluid is adjusted, and a numerical simulation analysis is performed on the battery cold plate, and the optimal type of the nanofluid is obtained according to the numerical simulation analysis result of the type of the nanofluid.

8. The nanofluid tree root-shaped cold plate according to claim 7, characterized in that: Based on the optimal type of nanofluid and taking the average battery temperature and pressure drop as the target, a battery thermal management model is constructed by the response surface method for the initial velocity, initial temperature and volume fraction of the nanofluid. The battery thermal management model is optimized and solved by the optimization algorithm to obtain the optimal initial velocity, optimal initial temperature and optimal volume fraction of the nanofluid.

9. The nanofluid tree root-shaped cold plate according to claim 8, characterized in that: The battery thermal management model is: Average battery temperature = -30.54991-30.40219A+1.26107B-0.663197C-0.001005AB+0.57495AC+0.001412BC+58.22538A 2 -0.00045B 2 +0.006018C 2 Pressure drop = 18.3984 + 315.27146A - 0.001015B - 1.67254C + 0.001545AB + 42.48479AC + 0.000112BC + 1851.788883A 2 +0B 2 +0.041202C 2 Wherein, A represents the initial velocity of the nanofluid, B represents the initial temperature of the nanofluid, and C represents the volume fraction of the nanofluid.

10. The nanofluid tree root-shaped cold plate according to claim 8, characterized in that: The optimization algorithm uses non-dominated sorting genetic algorithm.

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