Novel hybrid cooling battery thermal management system

Abstract

The invention discloses a novel hybrid cooling battery thermal management system, relates to the technical field of battery thermal management, and can give consideration to the heat dissipation performance and energy consumption of the battery thermal management system. The system comprises a battery pack, a cooling frame and a phase change sheet, the cooling frame comprises a first main pipeline, a second main pipeline and a plurality of parallel sub-pipelines, and each sub-pipeline communicates with the first main pipeline and the second main pipeline; the side surface of the sub-pipeline is attached to the side surface of the battery pack; and the phase-change sheets cling to the side surfaces of the sub-pipelines and the battery pack. The battery pack is cooled in a mode of combining the phase-change material and liquid cooling, so that the requirement on cooling capacity can be reduced, and the energy consumption of a thermal management system can be improved; after the cooling liquid is input into the cooling frame, the cooling liquid can be uniformly distributed on the side surface of the battery pack when circularly flowing through the sub-pipelines which are arranged in parallel and are attached to the side surface of the battery pack, so that the heat dissipation performance of the thermal management system can be improved, and meanwhile, the cooling frame is simple in structure, convenient to produce and capable of reducing the manufacturing cost.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and particularly to a novel hybrid cooling battery thermal management system. Background Art

[0002] Lithium batteries, as new energy storage media, have significant advantages, mainly reflected in high energy density, long cycle life, high efficiency, fast response, and environmental friendliness. These advantages make lithium batteries the mainstream choice in the field of new energy storage and are widely used in scenarios such as home energy storage, power grid peak shaving, and renewable energy storage.

[0003] Operating lithium-ion batteries in a high-temperature environment poses significant risks, mainly including accelerated internal chemical reactions of the battery, decomposition of the electrolyte, damage to the structures of the positive and negative electrode materials, and thermal runaway. High temperature can lead to an intensification of side reactions inside the battery. For example, the reaction between the electrolyte and the electrode material generates gas, increasing the internal pressure of the battery, which may cause the battery to expand or even rupture. At the same time, high temperature accelerates the decomposition of the electrolyte, reducing its ionic conductivity and affecting the battery performance. In addition, the positive electrode material (such as ternary material) may undergo a phase change or oxygen evolution at high temperature, while the negative electrode material (such as graphite) may form lithium dendrites, increasing the risk of short circuit. The most serious situation is thermal runaway, that is, the internal temperature of the battery rises sharply, triggering a chain exothermic reaction, and ultimately resulting in the battery catching fire or exploding. Therefore, a high-temperature environment poses a major threat to the safety, life, and performance of lithium-ion batteries, and effective thermal management systems and temperature monitoring measures must be adopted to prevent this.

[0004] Currently, the methods of battery thermal management systems on the market are to use phase change materials or liquid cooling systems for heat dissipation: Phase change materials do not require external energy input and have low energy consumption, but their thermal conductivity is usually low, and single-phase change material heat dissipation may lead to uneven heat distribution; Liquid cooling systems have good heat dissipation performance but high energy consumption, which is not conducive to environmental protection and energy conservation.

[0005] In view of this, a novel hybrid cooling battery thermal management system is needed. Summary of the Invention

[0006] Aiming at the problem that the existing battery thermal management system cannot balance heat dissipation performance and energy consumption, the present invention provides a novel hybrid cooling battery thermal management system that can balance the heat dissipation performance and energy consumption of the battery thermal management system. The specific technical solutions are as follows:

[0007] A novel hybrid cooling battery thermal management system, the system includes: a battery pack, a cooling rack, and a phase change sheet;

[0008] The cooling rack includes a first main pipe, a second main pipe, and a plurality of parallel sub-pipes. Each sub-pipe is respectively connected to the first main pipe and the second main pipe. The coolant inlet of the cooling rack is located in the first main pipe, and the coolant outlet of the cooling rack is located in the second main pipe. The cooling rack is used for the circulation of coolant. The first main pipe and the second main pipe are respectively arranged on opposite side surfaces of the battery pack, and the side surface of the sub-pipe is attached to the side surface of the battery pack. The phase change sheet is closely arranged against the side surfaces of the sub-pipe and the battery pack.

[0009] Preferably, the cooling rack includes a first cooling rack and a second cooling rack. The first main pipe of the first cooling rack and the first main pipe of the second cooling rack are fixedly connected, and the second main pipe of the first cooling rack and the second main pipe of the second cooling rack are fixedly connected. The battery pack is surrounded by the fixedly connected first cooling rack and second cooling rack.

[0010] Preferably, the battery pack includes a copper battery pack busbar, 4 positive plates, 4 negative plates, and 4 battery cells. The 4 battery cells are arranged in parallel at intervals. Each battery cell is respectively connected to the positive plate and the negative plate in a one-to-one correspondence. For two adjacent battery cells, the positive plate connected to one of them and the negative plate connected to the other are connected through the copper battery pack busbar.

[0011] Preferably, the phase change material filled in the phase change sheet includes n-heptane.

[0012] Preferably, the material of the cooling rack includes aluminum.

[0013] Preferably, the number of sub-pipes is 6.

[0014] Preferably, the parallel spacing between any two adjacent sub-pipes is the same.

[0015] Preferably, the cross-section of the sub-pipe is a square with side length D*D. The length of the battery cell is 20D, the height is 20D, and the parallel spacing is 1.66D. Wherein, D is a preset reference length.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The battery pack is cooled by combining a phase change material with liquid cooling. The phase change sheet can absorb a large amount of heat when the battery generates heat, delay the temperature rise, reduce the load of the liquid cooling system, and improve the energy consumption of the thermal management system. After the liquid cooling system is started, the coolant can quickly take away the heat stored in the phase change sheet, restart the phase change sheet, and ensure that the battery pack can still maintain a stable operating temperature under high-temperature or high-load conditions. In addition, the parallel sub-pipes attached to the side surface of the battery pack can make the coolant evenly distributed on the side surface of the battery pack during circulation, improve the heat dissipation performance and control efficiency of the thermal management system. At the same time, the simple structure is convenient for production and can reduce the manufacturing cost of the thermal management system. Brief Description of the Drawings

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0018] Figure 1 FIG. [0000036] is a schematic structural diagram of a novel hybrid cooling battery thermal management system provided by an embodiment of the present application;

[0019] Figure 2 FIG. [0000037] is a multi-view schematic diagram of a novel hybrid cooling battery thermal management system provided by an embodiment of the present application, where (a) is a top view, (b) is a bottom view, (c) is a front view, and (d) is a side view. Detailed Description of the Embodiments

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0022] It should also be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0023] It should be further understood that the term " / and / " used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0024] Liquid-cooled batteries have significant advantages as energy storage batteries, mainly reflected in aspects such as efficient thermal management capabilities, stable performance, long lifespan, and high safety. The liquid-cooling system can quickly and evenly absorb and dissipate heat by circulating a coolant (such as an ethylene glycol aqueous solution), ensuring that the battery operates within an appropriate temperature range, thereby effectively preventing performance degradation and lifespan shortening caused by overheating or overcooling of the battery. Compared with the air-cooling system, the liquid-cooling system has higher heat dissipation efficiency, especially suitable for energy storage scenarios with high energy density and high power requirements, and can significantly improve the charge-discharge efficiency and energy utilization rate of the battery. In addition, the liquid-cooling system can also reduce the uneven heat distribution inside the battery pack through precise temperature control, avoid safety hazards caused by local overheating, and further improve the reliability and safety of the system. The long lifespan of liquid-cooled batteries benefits from their optimized thermal management, which can effectively delay battery aging, reduce capacity decay, and thus lower the long-term operating cost of the energy storage system.

[0025] However, the energy consumption of the liquid-cooling system is relatively high, especially under high-temperature or high-load conditions, which may have a certain impact on the overall energy efficiency of the system (such as electric vehicles, server clusters) where it is located.

[0026] Phase change materials (PCMs) have unique advantages and limitations as thermal management solutions for energy storage batteries. Their advantages are mainly reflected in their efficient heat absorption and release capabilities: phase change materials can absorb a large amount of heat when undergoing a phase change within a specific temperature range, thereby effectively reducing the battery temperature and keeping the battery pack within an appropriate operating temperature range, avoiding overheating or overcooling problems. At the same time, their passive thermal management characteristics do not require external energy input, reducing system complexity and energy consumption. In addition, phase change materials have the advantages of being lightweight, having no moving parts, and high reliability, and are suitable for energy storage systems that are sensitive to space and weight. However, phase change materials also have some disadvantages: firstly, their thermal conductivity is usually low, which may lead to uneven heat distribution and requires combination with other thermal conductive materials to improve overall performance; secondly, the heat capacity of phase change materials is limited, and they may not be able to continuously and effectively cool down under extremely high temperatures or long-term high-load conditions; finally, the cost of phase change materials is relatively high, and their long-term stability and cycle service life still need to be further verified. In general, to improve performance,

[0027] The present invention combines a phase change material with liquid cooling to achieve long-term and effective performance control of batteries in a battery thermal management system. By combining the high-efficiency heat absorption capacity of the phase change material with the active heat dissipation performance of the liquid cooling system, more accurate and efficient temperature control can be achieved. When the battery temperature rises, the phase change material absorbs a large amount of heat, delaying the temperature rise and reducing the load on the liquid cooling system. After the liquid cooling system is started, the coolant can quickly remove the heat stored in the phase change material, ensuring that the battery pack can maintain a stable operating temperature under high-temperature or high-load conditions. This hybrid thermal management method not only improves the overall heat dissipation efficiency of the system, but also reduces the energy consumption and operating frequency of the liquid cooling system, thereby extending the battery life and improving safety. In addition, the passive thermal management characteristics of the phase change material reduce the dependence on external energy, while the flexibility of the liquid cooling system makes up for the deficiency of the phase change material in thermal conductivity, enabling the system to operate reliably in extreme environments. The present invention aims to invent a new type of high-efficiency phase change material and liquid cooling hybrid cooling system, providing a set of reliable, efficient, and low-energy-consuming battery solutions for future energy storage batteries.

[0028] An embodiment of the present application provides a battery thermal management system with a new type of hybrid cooling, which includes: a battery pack 11, a cooling rack 12, and a phase change sheet 13.

[0029] The cooling rack 12 includes a first main pipe, a second main pipe, and a plurality of parallel sub-pipes. Each sub-pipe is respectively connected to the first main pipe and the second main pipe; the coolant inlet of the cooling rack 12 (not shown in the figure) is located in the first main pipe, and the coolant outlet of the cooling rack 12 (not shown in the figure) is located in the second main pipe. The cooling rack 12 is used for the circulation of the coolant; the first main pipe and the second main pipe are respectively arranged on opposite sides of the battery pack 11, and the side surface of the sub-pipe is attached to the side surface of the battery pack 11; the phase change sheet 13 is attached to the side surfaces of the sub-pipe and the battery pack 11.

[0030] Preferably, as Figure 1 shown in the specific example of, the cooling rack 12 includes a first cooling rack and a second cooling rack. The first main pipe of the first cooling rack and the first main pipe of the second cooling rack are fixedly connected, and the second main pipe of the first cooling rack and the second main pipe of the second cooling rack are fixedly connected; the first cooling rack and the second cooling rack after being fixedly connected surround the battery pack. Such a structure facilitates the assembly and manufacture of the thermal management system.

[0031] It can be understood that in some other possible implementations, the thermal management system only includes one cooling rack 12; specifically, the first main pipe of the first cooling rack and the first main pipe of the second cooling rack in Figure 1 can be regarded as an integral first main pipe. The first main pipe is respectively connected to six sub-pipes on the left and right sides, and is connected to the second main pipe on the opposite side through the 12 sub-pipes (inFigure 1 The second main pipeline of the first cooling rack and the second main pipeline of the second cooling rack are regarded as a whole).

[0032] Preferably, the first main pipeline, the second main pipeline and all sub-pipelines are integrally formed; that is, the cooling rack 12 is integrally formed.

[0033] Preferably, the projection of the cooling rack 12 on the horizontal plane is rectangular. In this case, the space occupied by the cooling rack 12 and the battery pack 11 can be regarded as a rhombic prism, which is more convenient for the spatial layout when multiple battery packs 11 are jointly powered, and improves the space utilization rate of the system.

[0034] Preferably, the material of the cooling rack includes aluminum. When manufacturing batteries using phase change materials, the overweight cooling rack during the forming process is likely to damage the structure of the battery pack 11 or the comparison sheet 13, causing safety problems. To solve this problem, a lighter cooling rack is needed.

[0035] It can be understood that the thermal management system further includes a cooling unit (not shown in the figure), which is used to cool the coolant and input the cooled coolant into the cooling rack 12 through the coolant inlet of the first main pipeline; under the pumping action of the cooling unit, the cooled coolant reaches the second main pipeline through each sub-pipeline and returns to the cooling unit through the coolant outlet of the second main pipeline.

[0036] Among them, the battery pack 11 includes 4 sides, and the first main pipeline and the second main pipeline are respectively arranged on two opposite sides of the battery pack 11, so that the sub-pipelines can be attached to a larger area of the side of the battery pack 11, so that the coolant flowing in the sub-pipelines can fully absorb the heat dissipated by the battery. It can be understood that the first main pipeline and the second main pipeline can be arranged on two relatively narrow opposite sides of the battery pack 11, or can be arranged on two relatively wide sides. Preferably, as Figure 1 shown in the specific example, the first main pipeline and the second main pipeline are arranged on two relatively narrow opposite sides of the battery pack 11 for setting phase change sheets.

[0037] It can be understood that the fitting described in this document refers to the fitting in the mechanical field, that is, connecting or assembling two or more mechanical components in a tight, flat and mutually contacting manner to achieve specific functions or meet certain performance requirements.

[0038] Optionally, the side of the sub-pipeline is fixedly connected to the side of the battery pack 11 by bonding or other means.

[0039] Optionally, the cooling rack 12 and the phase change sheet 13 form a frame as Figure 1 shown, and the internal space of the frame is adapted to the size of the battery pack 11, so that the frame can wrap the battery pack 11.

[0040] Preferably, as in Figure 1 In the specific example shown, the number of sub-pipes is 6. Through calculation and experiment, setting 6 sub-pipes can keep the cross-sectional size of the sub-pipes at a reasonable level, ensure the heat absorption efficiency when the system performs active liquid cooling, and at the same time, the coolant can evenly cover the battery pack 11.

[0041] Preferably, the parallel spacing between any two adjacent sub-pipes is the same. In this way, when the system performs active liquid cooling, the coolant can evenly cover the battery pack 11.

[0042] Among them, as in Figure 1 The shown cooling rack has a simple structure and low manufacturing cost. At the same time, it can prevent the excessive cooling pipes from increasing the heat dissipation energy consumption and affecting the service life during the production and use of the battery pack 11.

[0043] Preferably, as in Figure 1 shown, the battery pack 11 includes a copper battery pack busbar 114, 4 positive plates 112, 4 negative plates 113 and 4 battery cells 111. The 4 battery cells 111 are arranged in parallel at intervals; each battery cell 111 is respectively connected to the positive plate 112 and the negative plate 113 in a one-to-one correspondence; for two adjacent battery cells 111, the positive plate 112 connected to one of them is connected to the negative plate 113 connected to the other through the copper battery pack busbar 114.

[0044] It can be understood that for the sake of simplicity of the drawings, Figure 1 not all components and labels are connected by straight lines in

[0045] Among them, the battery cell 111 is connected to the external power consumption system through the positive and negative electrode tabs and the copper battery pack busbar 114.

[0046] The design of this thermal management system refers to the physical parameters of phase change materials, the cooling efficiency of cooling pipes, and the manufacturing process and related safety issues of the battery pack. With the goal of making the most efficient use of the latent heat of phase change materials and the optimal heat dissipation performance (including integrity and timeliness), the optimal overall size is calculated.

[0047] For details, please refer to Figure 2 , Figure 2 which is a multi-view schematic diagram of a novel hybrid-cooling battery thermal management system provided by an embodiment of this application. Among them, (a) is a top view, (b) is a bottom view, (c) is a front view, and (d) is a side view.

[0048] As in Figure 2 shown, preferably, the cross-section of the sub-pipe is a square with side length D*D. The length of the battery cell is 20D, the height is 20D, and the parallel spacing is 1.66D; among them, D is a preset reference length.

[0049] Among them, the coolant inlet of the first main pipeline and the coolant outlet of the second main pipeline are 2D higher than the battery cell.

[0050] Among them, the length of the battery cell is 20D, and the width including the two side sub-pipelines is 22D; the overall width of the battery pack including the battery pack 11 and the cooling rack 12 is 22D.

[0051] Preferably, the phase change sheet 13 has a length of 22D, a width of D, and a height of the parallel spacing, or the distance between the sub-pipeline closest to both ends of the battery cell and the corresponding end. In this way, a structure as shown in Figure 1 and Figure 2 can be formed, and the side surface of the phase change sheet 13 and the side surface of the sub-pipeline form a plane.

[0052] In some other possible implementations, the sub-pipeline can surround the battery pack 11. More specifically, the inner edge of the projection of the sub-pipeline on the horizontal plane is adapted to the outer edge of the projection of the battery pack 11 on the horizontal plane.

[0053] Preferably, the phase change material filled in the phase change sheet 13 includes n-heptane. The reason for choosing n-heptane is that it has an appropriate phase change temperature, high heat absorption capacity, chemical stability, and low cost. Specifically, the phase change temperature range of n-heptane (about -90°C to -54°C) enables it to effectively absorb heat during high-temperature operation of the battery, delay the temperature rise, and reduce the risk of thermal runaway; at the same time, its high latent heat value (about 140 kJ / kg) ensures efficient heat storage and release capabilities, can absorb a large amount of heat in a short time, and significantly improves the thermal management efficiency of the battery. In addition, n-heptane has good chemical stability, is not easy to react with battery materials, is non-toxic and non-corrosive, and has high use safety. Compared with other phase change materials, n-heptane has a lower cost and is easy to obtain, making it suitable for large-scale commercial applications. These advantages make n-heptane a very promising phase change material for battery cooling, which can effectively improve the thermal management performance and safety of the battery system.

[0054] In the embodiments of the present application, the battery pack is cooled by combining the phase change material with liquid cooling. The phase change sheet can absorb a large amount of heat when the battery generates heat, delay the temperature rise, reduce the load of the liquid cooling system, and improve the energy consumption of the thermal management system; after the liquid cooling system is started, the coolant can quickly take away the heat stored in the phase change sheet, restart the phase change sheet, and ensure that the battery pack can still maintain a stable working temperature under high-temperature or high-load conditions. In addition, the sub-pipelines arranged in parallel and attached to the side of the battery pack can make the coolant evenly distributed on the side of the battery pack when circulating, improve the heat dissipation performance and control efficiency of the thermal management system, and at the same time, the simple structure is convenient for production and can reduce the manufacturing cost of the thermal management system.

[0055] Those of ordinary skill in the art can realize that the units of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components of each example have been generally described according to their functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0056] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0057] In several embodiments provided by the embodiments of the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in an electrical, mechanical, or other form.

[0058] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0059] In addition, the functional units in each embodiment of the present invention can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0060] When the above-mentioned functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, read-only memories (ROMs), random access memories (RAMs), mobile hard disks, magnetic disks, or optical discs that can store program codes.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered within the scope of the claims and the description of the present invention.

Claims

1. A new hybrid cooling battery thermal management system, characterized in that: The system comprises: a battery pack, a cooling rack and a phase change sheet; The cooling rack comprises a first main pipe, a second main pipe and a plurality of sub-pipes parallel to each other, each of the sub-pipes being connected to the first main pipe and the second main pipe respectively; a coolant inlet of the cooling rack is located in the first main pipe, a coolant outlet of the cooling rack is located in the second main pipe, and the cooling rack is used for circulating coolant; the first main pipe and the second main pipe are respectively arranged on two opposite sides of the battery pack, and the side of the sub-pipe is in contact with the side of the battery pack; The phase change sheet is arranged in contact with the side surfaces of the sub-pipe and the battery pack.

2. The system according to claim 1, characterized in that The cooling rack comprises a first cooling rack and a second cooling rack, the first main pipeline of the first cooling rack is fixedly connected to the first main pipeline of the second cooling rack, and the second main pipeline of the first cooling rack is fixedly connected to the second main pipeline of the second cooling rack; The first cooling rack and the second cooling rack that are fixedly connected surround the battery pack.

3. The system according to claim 1 or 2, characterized in that: The battery pack includes a copper battery pack busbar, four positive electrode sheets, four negative electrode sheets and four battery cells, wherein the four battery cells are arranged in parallel with each other; each of the battery cells is connected to the positive electrode sheet and the negative electrode sheet in a one-to-one correspondence; for two adjacent battery cells, the positive electrode sheet connected to one of them and the negative electrode sheet connected to the other are connected through the copper battery pack busbar.

4. The system according to claim 3, characterized in that The phase change material filled in the phase change sheet includes n-heptane.

5. The system according to claim 3, characterized in that The material of the cooling rack includes aluminum.

6. The system according to claim 3, characterized in that The number of sub-pipelines is 6.

7. The system according to claim 3, characterized in that The parallel spacing between any two adjacent sub-pipelines is the same.

8. The system according to claim 7, characterized in that The cross section of the sub-pipeline is a square with a side length of D*D, the length of the battery cell is 20D, the height is 20D, and the parallel spacing is 1.66D; wherein D is a preset reference length.

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