High heat transfer efficiency battery pack thermal management system and its inlet current collecting panel

Abstract

The application discloses a high heat exchange efficiency battery pack thermal management system and an import current collecting panel thereof; wherein, a flow equalizing structure is constructed in the inside of the import current collecting panel through generative design, including a flow blocking hole plate arranged between an import current collecting cavity and a water inlet main pipe, and a flow dividing fin arranged in the inside of the import current collecting cavity, the density of water permeable holes on the flow blocking hole plate gradually increases along the flow direction of the heat exchange medium in the water inlet main pipe (the density and size of the water permeable holes mainly depend on the fluid pressure difference and flow speed requirement on both sides of the flow blocking hole plate), the flow dividing fin is distributed around the import flow dividing groove in a streamline shape, and has different sizes and shapes at different positions, so that the heat exchange medium can be uniformly dispersed and guided to each heat exchange channel, the heat exchange medium flow in each heat exchange channel between adjacent battery cells is uniform, the flow speed is basically consistent, and the flow resistance is small, the heat exchange efficiency of the battery pack is improved, and the working temperature of the battery pack is conveniently and uniformly controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, in particular to a high heat transfer efficiency battery pack thermal management system and an import current collecting panel thereof. BACKGROUND

[0002] A large amount of heat is generated in the working process of the battery, which causes the temperature to rise. The excessively high temperature will affect the efficiency of the battery and reduce the cycle life of the battery. When the battery is installed in groups, the uneven temperature of the battery pack will cause inconsistent discharge and affect the power output of the battery pack. In order to ensure the use performance, safety and service life of the battery pack, the battery pack must be strengthened for thermal management, so that the battery pack always works in a suitable temperature range. The main functions of the battery pack thermal management include: effectively dissipating heat when the battery temperature is high to prevent thermal runaway accidents; preheating when the battery temperature is low to improve the battery temperature and ensure the charging and discharging performance and safety at low temperature; reducing the temperature difference in the battery pack and inhibiting the formation of local hot spots to prevent the rapid decay of the battery at high temperature and reduce the overall life of the battery pack.

[0003] At present, the battery pack generally adopts a series thermal management system, which has the advantages of simple structure and low manufacturing difficulty. However, the heat transfer effect is poor, the flow resistance is large, and the temperature gradient of the front and rear ends is obvious, which leads to poor control uniformity, affecting the safety, rate performance and cycle life of the battery pack. SUMMARY

[0004] In order to overcome the above problems existing in the prior art, the present application provides a high heat transfer efficiency battery pack thermal management system. The high heat transfer efficiency battery pack thermal management system of the present application has a flow equalizing structure constructed by generative design inside the import current collecting panel, which is used to realize parallel thermal management of the battery pack, so that the heat transfer medium in each heat transfer channel between adjacent battery cells is uniformly distributed, the flow rate is basically consistent, and the flow resistance is small, thereby improving the heat transfer efficiency of the battery pack. Correspondingly, the present application also provides an import current collecting panel for the high heat transfer efficiency battery pack thermal management system of the present application.

[0005] For the battery pack thermal management system, the technical scheme of the present application is:

[0006] The application discloses a high heat exchange efficiency battery pack thermal management system, which comprises an inlet manifold panel and an outlet manifold panel arranged in parallel and a battery pack arranged between the inlet manifold panel and the outlet manifold panel; the battery pack comprises electric cells stacked into one body, and a group of heat exchange channels are arranged between adjacent two electric cells; the inside of the inlet manifold panel is provided with a group of parallel inlet manifold cavities corresponding to the heat exchange channels; the inside of the outlet manifold panel is provided with a group of parallel outlet manifold cavities corresponding to the heat exchange channels; the edge of the inlet manifold panel is provided with an inlet water main communicating with the inlet of the inlet manifold cavities; the edge of the outlet manifold panel is provided with an outlet water main communicating with the outlet of the outlet manifold cavities; the side of the inlet manifold panel in contact with the electric cells is provided with a group of parallel long strip-shaped inlet distribution grooves; the side of the outlet manifold panel in contact with the electric cells is provided with a group of parallel long strip-shaped outlet distribution grooves; the two ends of the heat exchange channels are aligned with the inlet distribution grooves and the outlet distribution grooves respectively, so that the inlet manifold cavities and the outlet manifold cavities distributed on the two sides of the electric cells are communicated.

[0007] The inside of the inlet manifold panel is constructed with a flow uniformizing structure through generative design, which is used for uniformly distributing the heat exchange medium entering the inlet manifold panel to each heat exchange channel; the flow uniformizing structure comprises a flow blocking hole plate arranged between the inlet manifold cavities and the inlet water main, and a group of distribution fins arranged in the inside of the inlet manifold cavities; the flow blocking hole plate is provided with water permeable holes, and the density of the water permeable holes gradually increases along the flow direction of the heat exchange medium in the inlet water main; the distribution fins are distributed around the inlet distribution grooves in a streamline shape.

[0008] The specific steps of the generative design are as follows:

[0009] S1, defining the space in the inside of the inlet manifold panel as the solution domain of the generative design, defining the size and position of the inlet distribution grooves, and defining the size and position of the inlet water main;

[0010] S2, defining the physical parameters and inlet flow rate of the heat exchange medium, and setting the uniformity of the inlet distribution grooves and the pressure drop target;

[0011] S3, arranging an initial flow blocking hole plate beside the inlet water main in the solution domain space, and empirically allocating the original seed positions of the water permeable holes on the flow blocking hole plate and assigning initial sizes; a plurality of distribution fins are arranged around the inlet distribution grooves, the original seed positions of the distribution fins are empirically allocated, and initial lengths, thicknesses and curvatures are assigned; the above optimization parameters (i.e. the positions, lengths, thicknesses and curvatures of the distribution fins, and the positions and sizes of the water permeable holes) are set, and the uniformity of the inlet distribution grooves and the overall flow resistance are set as response variables;

[0012] S4, using Navier-Stokes equation or its derived fluid dynamics control equation to calculate the steady-state fluid distribution and overall pressure drop in the solution domain; after obtaining the steady-state solution, comparing the existing results with the target uniformity and pressure drop, using particle swarm algorithm and genetic algorithm to fill or delete the existing space structure once, generating a new structure, and re-solving;

[0013] S5, repeating the iteration step S4 until the uniformity and pressure drop target of the inlet flow dividing groove are reached, and the flow uniformity structure is completed.

[0014] Compared with the prior art, the high heat exchange efficiency battery pack thermal management system of the application has a flow uniformity structure constructed by generative design in the interior of the inlet flow collecting panel, which is used to realize parallel thermal management of the battery pack, conforms to fluid dynamics, and has low flow resistance; the flow uniformity structure includes a flow blocking hole plate arranged between the inlet flow collecting cavity and the water inlet main pipe and a flow dividing fin arranged in the interior of the inlet flow collecting cavity, wherein the density of the water permeable holes on the flow blocking hole plate gradually increases along the flow direction of the heat exchange medium in the water inlet main pipe (the density and size of the water permeable holes are variable amounts mainly determined by the fluid pressure difference and flow speed requirement on both sides of the flow blocking hole plate. The flow speed and pressure difference near the inlet of the water inlet main pipe are large, and the density of the water permeable holes is small), and the flow dividing fins are distributed around the inlet flow dividing groove in a streamline shape and have different sizes and shapes at different positions, so that the heat exchange medium entering the inlet flow collecting panel can be uniformly dispersed and guided to each heat exchange channel, the flow of the heat exchange medium in each heat exchange channel between the adjacent two battery cells is uniform, the flow speed is basically consistent, and the flow resistance is small, thereby improving the heat exchange efficiency of the battery pack and facilitating precise and uniform control of the working temperature of the battery pack.

[0015] As an optimization, in the aforementioned high heat exchange efficiency battery pack thermal management system, the battery cell includes a set of first battery cells and a set of second battery cells stacked at intervals; a set of flow guide grooves are arranged at intervals on the outer surface of the first battery cell, forming a set of heat exchange channels between the adjacent first battery cell and second battery cell for the flow of heat exchange medium. At this time, the heat exchange medium directly contacts the outer surfaces of the two side battery cells, so that efficient convective heat transfer between the heat exchange medium and the battery cell can be realized, further improving the heat exchange efficiency of the battery pack. A set of flow guide grooves can be constructed on one side of the outer surface of the first battery cell; or a set of flow guide grooves can be constructed on both sides of the outer surface of the first battery cell. When both sides of the first battery cell are provided with flow guide grooves, heat exchange channels can be formed on both sides of the first battery cell and the second battery cell, and the first battery cell and the second battery cell are simultaneously subjected to heat exchange, thereby achieving higher heat exchange efficiency.

[0016] Further, the first and second electric cores are externally provided with hard shells; the hard shells are processed and formed by hot extrusion, milling, adhesive welding or additive manufacturing of metal materials (which can be selected from aluminum, steel and other hard materials with good thermal conductivity). Thus, the electric core has sufficient strength, and the adjacent two electric cores are conveniently installed and fixed. Further, the first and second electric cores can be fixed as a whole by welding and other rigid connection methods. At this time, the operation is simple, and the connection firmness is high.

[0017] As an optimization, in the aforementioned high heat exchange efficiency battery pack thermal management system, steel belts or screws are arranged on two sides of the battery pack perpendicular to the stacking direction of the first and second electric cores to constrain internal stress. In use, the electric core can be prevented from swelling while maintaining the structural stability of the heat exchange channel.

[0018] As an optimization, in the aforementioned high heat exchange efficiency battery pack thermal management system, the distance between the adjacent two inlet branch grooves can be 5-50 mm, and the distance between the adjacent two outlet branch grooves can be 5-50 mm. Thus, the battery pack can have high heat transfer performance.

[0019] As an optimization, in the aforementioned high heat exchange efficiency battery pack thermal management system, the shape of the water-permeable hole can be circular, square or special-shaped. At this time, the manufacturing is convenient.

[0020] As an optimization, in the aforementioned high heat exchange efficiency battery pack thermal management system, the inlet and outlet collecting panels can be integrally formed by additive manufacturing of a high polymer material. Thus, the inlet and outlet collecting panels have the characteristics of light weight, high strength and high temperature resistance.

[0021] As an optimization, in the aforementioned high heat exchange efficiency battery pack thermal management system, the inlet and outlet collecting panels are connected to the battery pack by gluing, screwing, riveting or inserting, and are sealed by sealing glue to fixedly connect the inlet and outlet collecting panels and the battery pack as a whole. At this time, the structure is simple and easy to assemble.

[0022] For the inlet collecting panel, the technical solution of the application is:

[0023] The import current collecting panel of high heat exchange efficiency battery pack thermal management system, the inside of the import current collecting panel is provided with a group of parallel import current collecting cavities, the edge is provided with an import water main pipe communicated with the import current collecting cavity, one surface of the import current collecting panel is provided with a group of parallel long strip import shunt grooves; the inside of the import current collecting panel is constructed with a flow equalizing structure through generative design; the flow equalizing structure includes a flow blocking hole plate between the import current collecting cavity and the import water main pipe, and a group of shunt fins in the import current collecting cavity; the flow blocking hole plate is provided with water permeable holes, the density of the water permeable holes gradually increases along the flow direction of the heat exchange medium in the import water main pipe; the shunt fins are distributed around the import shunt groove in streamline shape;

[0024] The specific steps of the generative design are as follows:

[0025] S1, defining the space inside the import current collecting panel as the solution domain of the generative design, defining the size and position of the import shunt groove, and defining the size and position of the import water main pipe;

[0026] S2, defining the physical parameters and inlet flow velocity of the heat exchange medium; setting the uniformity and pressure drop target of the import shunt groove;

[0027] S3, setting the initial flow blocking hole plate beside the import water main pipe in the solution domain space, and empirically allocating the original seed position of the water permeable hole on the flow blocking hole plate and assigning the initial size; setting a plurality of shunt fins around the import shunt groove, empirically allocating the original seed position and assigning the initial length, thickness and curvature; setting the above optimization parameters, and setting the uniformity and overall flow resistance of the import shunt groove as the response variable;

[0028] S4, using Navier-Stokes equation or its derived fluid dynamics control equation to calculate the steady-state fluid distribution and overall pressure drop in the solution domain; after obtaining the steady-state solution, comparing the existing results with the target uniformity and pressure drop, using particle swarm algorithm and genetic algorithm to fill or delete the existing space structure once, generating a new structure, and re-solving;

[0029] S5, repeating the iteration step S4 until the uniformity and pressure drop target of the import shunt groove are reached, and the flow equalizing structure is constructed.

[0030] Compared with the prior art, the high heat exchange efficiency battery pack thermal management system of the application has a flow equalizing structure in the internal part of the inlet flow collecting panel, which is constructed by generative design, and the flow equalizing structure includes a flow blocking hole plate arranged between the inlet flow collecting cavity and the water inlet main pipe and a flow dividing fin arranged in the internal part of the inlet flow collecting cavity, wherein the density of the water permeable holes on the flow blocking hole plate gradually increases along the flow direction of the heat exchange medium in the water inlet main pipe, the flow dividing fin is distributed around the inlet flow dividing groove in a streamline shape and has different sizes and shapes at different positions, so that the heat exchange medium entering the inlet flow collecting panel can flow out uniformly from the inlet flow dividing groove; after the inlet flow collecting panel is applied to the battery pack thermal management system, the heat exchange medium in the internal part of the inlet flow collecting panel can be uniformly divided into each heat exchange channel between the adjacent two battery cells, the flow rate of the heat exchange medium in each heat exchange channel is basically consistent, and the heat exchange efficiency of the battery pack is improved. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structural schematic diagram of the high heat exchange efficiency battery pack thermal management system of the application;

[0032] Figure 2 is a structural schematic diagram of the outlet flow collecting panel in the application;

[0033] Figure 3 is a sectional view of the outlet flow collecting panel in the application;

[0034] Figure 4 is a structural schematic diagram of the inlet flow collecting panel in the application;

[0035] Figure 5 is a sectional view of the inlet flow collecting panel in the application;

[0036] Figure 6 is a distribution schematic diagram of the flow dividing fin in the inlet flow collecting cavity in the application;

[0037] Figure 7 is a structural schematic diagram of the battery pack in the application;

[0038] Figure 8 is a structural schematic diagram of the first battery cell in the application;

[0039] Figure 9 is an assembly schematic diagram of the first battery cell and the second battery cell in the application;

[0040] Figure 10 is a structural schematic diagram of the flow blocking hole plate in the application;

[0041] Figure 11 is a step flow chart of the generative design in the application;

[0042] Figure 12 is a relationship diagram of the PTC resistor and the flow rate.

[0043] The marks in the drawings are: 1 - inlet flow collection panel, 101 - inlet flow collection cavity, 102 - water inlet main pipe, 103 - inlet flow distribution groove, 104 - flow blocking hole plate, 105 - flow distribution fin, 106 - first installation groove, 107 - first partition plate; 2 - outlet flow collection panel, 201 - outlet flow collection cavity, 202 - water outlet main pipe, 203 - outlet flow distribution groove, 204 - second installation groove, 205 - second partition plate; 3 - battery pack, 31 - first electric core, 3101 - flow guide groove, 32 - second electric core, 33 - steel plate; 4 - fixing plate. DETAILED DESCRIPTION

[0044] The application will be further described below in conjunction with the drawings and examples, but not as the basis for limiting the application.

[0045] Reference Figures 1 to 10 The high heat exchange efficiency battery pack thermal management system of the application comprises an inlet flow collection panel 1 and an outlet flow collection panel 2 arranged in parallel, and a battery pack 3 arranged between the inlet flow collection panel 1 and the outlet flow collection panel 2; the battery pack 3 comprises electric cores stacked into one body, and a group of heat exchange channels is arranged between adjacent two electric cores; the interior of the inlet flow collection panel 1 is separated into a group of parallel inlet flow collection cavities 101 by a first partition plate 107 corresponding to each group of heat exchange channels, and the interior of the outlet flow collection panel 2 is separated into a group of parallel outlet flow collection cavities 201 by a second partition plate 205; the long edge of the inlet flow collection panel 1 is provided with a water inlet main pipe 102 in communication with the inlet of the inlet flow collection cavity 101, and the long edge of the outlet flow collection panel 2 is provided with a water outlet main pipe 202 in communication with the outlet of the outlet flow collection cavity 201; the side of the inlet flow collection panel 1 in contact with the electric core is provided with a group of parallel long strip-shaped inlet flow distribution grooves 103, and the side of the outlet flow collection panel 2 in contact with the electric core is provided with a group of parallel long strip-shaped outlet flow distribution grooves 203; the two ends of the heat exchange channels are respectively aligned with the inlet flow distribution grooves 103 and the outlet flow distribution grooves 203, so that the inlet flow collection cavities 101 and the outlet flow collection cavities 201 distributed on both sides of the electric core are communicated;

[0046] The interior of the import manifold panel 1 is constructed with a flow uniformization structure by generative design, for uniformly distributing the heat exchange medium entering the import manifold panel 1 to each heat exchange channel; the flow uniformization structure comprises a flow blocking orifice plate 104 (for flow distribution in a high flow speed area, located beside the main inlet channel) arranged between the import manifold cavity 101 and the water inlet main pipe 102, and a set of flow distribution fins 105 (for flow distribution in a low flow speed area, located around the import flow distribution groove 103) arranged inside the import manifold cavity 101; the flow blocking orifice plate 104 is provided with water permeable holes 1041, the density of the water permeable holes 1041 gradually increases along the flow direction of the heat exchange medium in the water inlet main pipe 102; the flow distribution fins 105 are distributed in a streamline shape around the import flow distribution groove 103;

[0047] The specific steps of the generative design are as follows (see Figure 12 ):

[0048] S1, defining the space where the import manifold panel 1 is located as the solution domain of the generative design, defining the size and position of the import flow distribution groove 103, and defining the size and position of the water inlet main pipe 102;

[0049] S2, defining the physical parameters (i.e. a series of fluid physical parameters) and inlet flow speed of the heat exchange medium (the heat exchange medium can be gas or liquid); setting the uniformity and pressure drop targets of the import flow distribution groove 103;

[0050] S3, arranging an initial flow blocking orifice plate 104 beside the water inlet main pipe 102 in the solution domain space, and empirically allocating original seed positions of the water permeable holes 1041 on the flow blocking orifice plate 104 and assigning initial key parameters such as size; arranging a plurality of flow distribution fins 105 around the import flow distribution groove 103, empirically allocating original seed positions thereof and assigning initial key parameters such as length, thickness, curvature, etc.; setting the above optimization parameters (i.e. the positions, length, thickness, curvature, etc. of the flow distribution fins 105, and the positions, size, etc. of the water permeable holes 1041), and setting the uniformity and overall flow resistance of the import flow distribution groove 103 as response variables;

[0051] S4, using the Navier-Stokes equation or its derived fluid dynamics control equation to calculate the steady-state fluid distribution and overall pressure drop in the solution domain, after obtaining the steady-state solution, comparing the existing results with the target uniformity and pressure drop, using the particle swarm algorithm and genetic algorithm to fill or reduce the existing space structure once, generating a new structure, and re-solving (specifically: first, initialize the particle swarm, set the position and velocity of each particle, represent the solution space of the topological design; second, calculate the fitness function value of each particle, evaluate the performance of the design scheme; then, update the position and velocity of the particles, use the global optimal solution to guide the search direction, and gradually optimize the design scheme);

[0052] S5, repeating the iteration of step S4 until the uniformity and pressure drop targets of the inlet flow splitter 103 are reached, the flow uniformity structure is constructed, and the three-dimensional file of the final inlet flow collector panel 1 is output.

[0053] Embodiment:

[0054] In this embodiment, the battery cell includes a set of first battery cells 31 and a set of second battery cells 32 stacked in intervals; a set of flow guide grooves 3101 is arranged on one side of the first battery cell 31 in intervals, forming a set of heat exchange channels between adjacent first battery cells 31 and second battery cells 32 for the flow of heat exchange medium.

[0055] In this embodiment, the distance between two adjacent inlet flow splitters 103 is 25 mm, and the distance between two adjacent outlet flow splitters 203 is also 25 mm. In this way, the battery pack can have high heat transfer performance.

[0056] In this embodiment, the first battery cell 31 and the second battery cell 32 are both 20 Ah ternary lithium square battery cells, produced and manufactured using a lamination process.

[0057] The material of the hard shell of the battery cell is a 5000 series welded aluminum alloy, and the main components are Zn (0.5-6.1%), Mg (0.1-2.9%), Cu (0.1-2.0%), and the balance of aluminum; it is first formed by hot extrusion, specifically, by passing a preheated aluminum alloy blank through a special-shaped die under high pressure to form a square-sectioned L-shaped profile, with a cross-sectional size of 13 mm x 120 mm and a profile wall thickness of 1.5 mm; the main parameters include extrusion temperature (450 degrees Celsius), extrusion speed (50 mm per second), die temperature (350 degrees Celsius), and extrusion pressure (140 MPa); after hot extrusion, a set of flow guide grooves 3101 are machined on the large-area surface of the profile using a milling process, with a groove width of 18 mm, a groove depth of 1 mm, and an adjacent groove spacing of 1 mm.

[0058] After the hard shell is manufactured, the square battery cell is processed. First, the battery materials are prepared, including the ternary positive material, artificial graphite negative material, and separator film. First, the nickel-cobalt-manganese ternary positive material (NCM811) is mixed with a conductive agent (graphite and carbon black) in a certain proportion; then, a binder (polyacrylic acid or polyvinyl acetate, accounting for about 3% of the total mass of the slurry) and a solvent (N-methyl-2-pyrrolidone) are added to prepare a uniform slurry; the mass ratio of the ternary positive material to the conductive agent is about 96:4; then, the slurry is coated on an aluminum foil current collector, and the coating thickness is controlled by a doctor blade; the coating thickness is between 100-200 μm; next, drying treatment is performed, which is divided into pre-drying and main drying stages, the pre-drying temperature is 100°C, the main drying temperature is 130°C, and the drying time is 80 minutes; finally, the coated electrode sheet is compacted to a thickness of 80 microns by a pressure roller. Next, the positive and negative electrode materials are coated on a conductive substrate and dried and compacted to form an electrode sheet. Then, the electrode sheet and the separator film are alternately stacked and cut to a predetermined size. Next, the stacked electrode sheet is placed in a square hard shell and electrolyte is injected. Finally, the square battery cell is packaged, and charge and discharge tests and aging treatment are performed to ensure stable and reliable cell performance. The entire process is carried out under strict environmental conditions.

[0059] In this embodiment, the first cell 31 and the second cell 32 are fixed by welding; the joint of the most surface of the adjacent cells is sealed after laser welding to fix the first cell 31 and the second cell 32 as a whole.

[0060] Further, on the two sides of the battery pack 3, perpendicular to the stacking direction of the first cell 31 and the second cell 32, a steel belt 33 is provided, which is welded to the side of the first cell 31 and the second cell 32, used to constrain internal stress and prevent cell expansion, while maintaining the structural stability of the heat exchange channel. At this time, the entire battery pack 3 is a load-bearing rigid structure.

[0061] In this embodiment, the energy of the battery pack 3 constructed is 5.2 kilowatt-hours, and the voltage is 120 volts; the size is 590 millimeters x 140 millimeters x 115 millimeters; the mass energy density is 190 watt-hours per kilogram.

[0062] In this embodiment, the inlet current collecting panel 1 is provided with a first mounting groove 106, and the outlet current collecting panel 1 is provided with a second mounting groove 204. During assembly, the lower end of the battery pack 3 welded as a whole is placed in the first mounting groove 106, and the upper end is placed in the second mounting groove 204, and sealing is realized through sealing glue; then two fixing plates 4 are used to connect the two ends of the inlet current collecting panel 1 and the outlet current collecting panel 2 together, and the inner surfaces of the two fixing plates 4 respectively abut against the outer surfaces of the first and last two battery cells; and the two ends of the steel belt 33 are respectively welded and fixed with the two fixing plates 4 on the sides. Thus, the inlet current collecting panel 1, the outlet current collecting panel 2 and the battery pack 3 are fixedly connected as a whole, and at this time, the structure is simple and easy to assemble.

[0063] In this embodiment, the inlet current collecting panel 1 and the outlet current collecting panel 2 are integrally formed by additive manufacturing of high molecular material nylon PA66. Thus, the inlet current collecting panel 1 and the outlet current collecting panel 2 have the characteristics of light weight, high strength and high temperature resistance.

[0064] In the generative design of this embodiment, the size of the inlet current collecting panel 1 is defined as 590 mm x 140 mm x 8 mm, and the size of the inlet water main pipe 102 is 590 mm x 8 mm x 8 mm; the inlet shunt groove 103 is long strip-shaped, and the spacing between adjacent two inlet shunt grooves 103 is 25 mm; the flow blocking hole plate 104 is arranged beside the inlet water main pipe 102, and the shape of the water permeable hole 1041 is circular; the heat exchange medium is ethylene glycol antifreeze, and the main components are ethylene glycol, corrosion inhibitor, antifoaming agent and rust inhibitor; the inlet flow rate of the heat exchange medium is 8 liters per minute; the freezing point of the heat exchange medium is usually between -25℃ and -50℃, the boiling point is generally between 100℃ and 130℃, the density is usually between 1.03 and 1.15 g / cm3, and the dynamic viscosity is usually between 1 and 4 mPa·s, and the specific values are affected by the ethylene glycol concentration, temperature and other components, and are considered in the generative design simulation.

[0065] In order to verify the uniformity of heat dissipation of the battery pack heat management system, the inventors use a self-developed test device to detect the flow rate of the heat exchange medium at different positions in the battery pack heat management system to obtain the overall flow rate distribution; the test device is developed based on the non-invasive flow rate measurement principle of PTC (positive temperature coefficient thermistor).

[0066] The non-invasive flow rate measurement principle based on PTC is to infer the flow rate by measuring the cooling effect of the fluid on the sensor. This method does not require direct contact with the fluid, so it is called non-invasive. The PTC thermistor has a special characteristic that its resistance value changes with temperature, so the flow rate can be inferred according to the change of the resistance value. The basic principle is as follows:

[0067] 1) PTC thermistor is heated to a stable temperature, usually higher than the fluid temperature;

[0068] 2) When the fluid passes through the thermistor, it will have a cooling effect on it, causing the temperature of the thermistor to drop (the cooling effect is proportional to the flow rate, the greater the flow rate, the more obvious the cooling effect);

[0069] 3) Since the resistance value of the PTC thermistor changes with temperature, when the fluid cools the thermistor, the resistance value of the thermistor will also change, which can be detected by measuring the resistance value;

[0070] 4) By collecting the resistance value change data of the thermistor, the fluid flow rate can be derived.

[0071] The specific operation steps of the flow rate test are as follows:

[0072] 1) Calibrate a model of the relationship between the flow rate of the heat exchange medium and the change of the resistance value; connect the two ends of the aluminum flat tube to the water inlet and outlet pipes by brazing, and select cooling water as the heat exchange medium; control the water flow rate through the aluminum flat tube, with a water temperature of 20 degrees Celsius and a speed range of 0 to 50 millimeters per second; press the PTC probe tightly against the surface of the aluminum flat tube; due to the cooling effect of the flowing water, the resistance value of the PTC probe gradually decreases and the current gradually increases, and the resistance value is recorded after it stabilizes;

[0073] 2) Repeat step 1) to obtain the relationship between PTC resistance and flow rate (see Figure 11 ), as the calibration basis for measurement;

[0074] 3) After the battery pack thermal management system of the present application is assembled, all materials inside the battery cell are removed, leaving only the hard shell, which contains a total of 26 thermal management interfaces (i.e. the wall surface of the battery cell in contact with the cooling water);

[0075] 4) Measure the flow rate data at the middle position and near the four corners of each thermal management interface; specifically, insert the heated PTC probe into the battery cell and make it contact with the thermal management interface of the battery cell shell, monitor the change of its resistance value and wait for the value to stabilize, then use the pre-calibrated relationship model to deduce the flow rate.

[0076] The measurement results are shown in Tables 1 and 2:

[0077] Table 1: Flow rate measurement results at the center position of some thermal management interfaces

[0078] Interface number 1 3 5 7 9 Flow rate (mm / s) 25.6 25.3 26.7 22.6 25.6 Interface number 11 13 15 17 19 Flow rate (mm / s) 24.9 23.7 25.8 25.3 24.8 Interface number 21 23 25 Flow rate (mm / s) 23.7 24.4 24.5

[0079] Table 2: Flow rate measurement results at the center and four corners of the 15th thermal management interface

[0080] Position Flow rate (mm / s) Center 25.8 Top left 23.5 Bottom left 24.5 Top right 25.8 Bottom right 26.6

[0081] The general description of the invention involved in the present application and the description of its specific embodiments should not be understood as a limitation on the technical solutions of the invention. Based on the disclosure of the present application, the skilled in the art can add, reduce, split or combine the disclosed technical features in the general description or / and the specific embodiments (including examples) without violating the elements of the invention involved, to form other technical solutions within the protection scope of the present application.

[0082] For example, the main innovative function of the import manifold plate is to evenly disperse the concentrated flow of heat management medium to multiple heat exchange channels between two adjacent battery cells through the internal flow blocking hole plate and flow splitting fin structure, while meeting the requirements of overall volume, weight and flow resistance. Hollow plate-shaped flow splitting structures that meet this requirement are within the protection scope of this patent. Changes to the number, position and size of the flow blocking hole plate and flow splitting fin structure, or the use of only one of the flow blocking hole plate and flow splitting fin structure, are obvious modifications based on this invention patent. In addition, adjustments to the flow direction of the heat management medium, the position, shape and number of inlets and outlets also do not deviate from the protection scope of this invention patent.

[0083] For another example, the preferred battery cell structure in the present invention is a hard-shell square battery cell, but soft-pack battery cells can also be placed in a hard shell or adhered to the surface of a hard metal profile to build a similar heat management system. Such modifications and optimizations are obvious to industry professionals and do not deviate from the protection scope of this invention patent.

Claims

1. A high heat transfer efficiency battery pack thermal management system characterized by: The application relates to a battery pack, which comprises an inlet flow collection panel (1) and an outlet flow collection panel (2) arranged in parallel, and a battery pack (3) arranged between the inlet flow collection panel (1) and the outlet flow collection panel (2); the battery pack (3) comprises electric cells stacked in one body, and a group of heat exchange channels are arranged between two adjacent electric cells; corresponding to each group of heat exchange channels, a group of parallel inlet flow collection cavities (101) are arranged in the interior of the inlet flow collection panel (1), and a group of parallel outlet flow collection cavities (201) are arranged in the interior of the outlet flow collection panel (2); a water inlet main pipe (102) is arranged on the edge of the inlet flow collection panel (1) and communicates with the inlet of the inlet flow collection cavity (101), and a water outlet main pipe (202) is arranged on the edge of the outlet flow collection panel (2) and communicates with the outlet of the outlet flow collection cavity (201); a group of parallel long strip-shaped inlet flow distribution grooves (103) are arranged on the side of the inlet flow collection panel (1) and in contact with the electric cells, and a group of parallel long strip-shaped outlet flow distribution grooves (203) are arranged on the side of the outlet flow collection panel (2) and in contact with the electric cells; the two ends of the heat exchange channels are aligned with the inlet flow distribution grooves (103) and the outlet flow distribution grooves (203) respectively, so that the inlet flow collection cavities (101) and the outlet flow collection cavities (201) distributed on the two sides of the electric cells are communicated; A flow uniformizing structure is constructed in the interior of the inlet flow collection panel (1) through generative design, which is used for uniformly distributing the heat exchange medium entering the inlet flow collection panel (1) to each heat exchange channel; the flow uniformizing structure comprises a flow blocking hole plate (104) arranged between the inlet flow collection cavity (101) and the water inlet main pipe (102), and a group of flow distribution fins (105) arranged in the interior of the inlet flow collection cavity (101); the flow blocking hole plate (104) is provided with water permeable holes (1041), and the density of the water permeable holes (1041) gradually increases along the flow direction of the heat exchange medium in the water inlet main pipe (102); the flow distribution fins (105) are distributed around the inlet flow distribution groove (103) in a streamline shape; The specific steps of the generative design are as follows: S1, defining the space in the interior of the inlet flow collection panel (1) as the solution domain of the generative design, defining the size and position of the inlet flow distribution groove (103), and defining the size and position of the water inlet main pipe (102); S2, defining the physical parameters and inlet flow velocity of the heat exchange medium; setting the uniformity of the inlet flow distribution groove (103) and the pressure drop target; S3, setting an initial flow blocking hole plate (104) beside the water inlet main pipe (102) in the solution domain space, empirically allocating the original seed positions of the water permeable holes (1041) on the flow blocking hole plate (104) and assigning initial sizes; a plurality of flow distribution fins (105) are arranged around the inlet flow distribution groove (103), the original seed positions of the flow distribution fins (105) are empirically allocated, and initial lengths, thicknesses and curvatures are assigned; setting the above optimization parameters, including the positions, lengths, thicknesses and curvatures of the flow distribution fins (105), and the positions and sizes of the water permeable holes (1041), and setting the uniformity of the inlet flow distribution groove (103) and the overall flow resistance as response variables; S4, using Navier-Stokes equation or its derived fluid dynamics control equation to calculate the steady-state fluid distribution and overall pressure drop in the solution domain; after obtaining the steady-state solution, the existing results are compared with the target uniformity and pressure drop, and the particle swarm algorithm and genetic algorithm are used to fill or delete the existing space structure once to generate a new structure and re-solve; S5, repeat step S4 until the uniformity and pressure drop of the inlet flow dividing groove (103) reach the target, and the flow uniformity structure is completed.

2. The high heat transfer efficiency battery pack thermal management system of claim 1, wherein: The battery cell includes a set of first battery cells (31) and a set of second battery cells (32) stacked at intervals; a set of flow guide grooves (3101) is arranged at intervals on the outer surface of the first battery cell (31), and a set of heat exchange channels is formed between adjacent first battery cells (31) and second battery cells (32).

3. The high-efficiency heat transfer battery pack thermal management system of claim 2, wherein: The first battery cell (31) and the second battery cell (32) are both provided with a hard shell, which is processed by hot extrusion, milling, adhesive welding or additive manufacturing.

4. The high-efficiency heat transfer battery pack thermal management system of claim 3, wherein: The first battery cell (31) and the second battery cell (32) are fixed together by a rigid connection mode.

5. The high-efficiency heat transfer cell pack thermal management system of claim 4, wherein: Steel belts or screws are arranged on both sides of the battery pack (3) perpendicular to the stacking direction of the first battery cell (31) and the second battery cell (32) to constrain the internal stress.

6. The high-efficiency heat transfer cell pack thermal management system of claim 1, wherein: The distance between two adjacent inlet flow dividing grooves (103) is 5-50 mm, and the distance between two adjacent outlet flow dividing grooves (203) is also 5-50 mm.

7. The high-efficiency heat transfer cell pack thermal management system of claim 1, wherein: The shape of the water permeable hole (1041) is circular, square or special-shaped.

8. The high-efficiency heat transfer cell pack thermal management system of claim 1, wherein: The inlet flow collecting panel (1) and the outlet flow collecting panel (2) are integrally formed by additive manufacturing of high molecular materials.

9. The high-efficiency heat transfer cell pack thermal management system of claim 8, wherein: The inlet flow collecting panel (1) and the outlet flow collecting panel (2) are connected with the battery pack (3) by adhesive bonding, screwing, riveting or inserting, and are sealed by sealing glue.

10. An inlet current collector panel for a high heat transfer efficiency battery pack thermal management system, characterized by: The inlet flow collecting panel (1) is provided with a set of parallel inlet flow collecting cavities (101) inside, and the edge is provided with an inlet water main pipe (102) in communication with the inlet flow collecting cavities (101); one surface of the inlet flow collecting panel (1) is provided with a set of parallel strip-shaped inlet flow dividing grooves (103); the inlet flow collecting panel (1) is provided with a flow uniformity structure by generative design; the flow uniformity structure includes a flow blocking hole plate (104) arranged between the inlet flow collecting cavities (101) and the inlet water main pipe (102), and a set of flow dividing fins (105) arranged inside the inlet flow collecting cavities (101); the flow blocking hole plate (104) is provided with a water permeable hole (1041), and the density of the water permeable hole (1041) gradually increases along the flow direction of the heat exchange medium in the inlet water main pipe (102); the flow dividing fins (105) are distributed around the inlet flow dividing grooves (103) in a streamline shape. The specific steps of the generative design are as follows: S1, define the space inside the inlet flow collecting panel (1) as the solution domain of the generative design, define the size and position of the inlet flow dividing groove (103), and define the size and position of the inlet water main pipe (102); S2, define the physical parameters of heat exchange medium and inlet flow rate; set the uniformity of inlet flow dividing groove (103) and pressure drop target; S3, set initial flow blocking orifice plate (104) beside inlet water main (102) in solving domain space, and distribute original seed position of water permeable hole (1041) on flow blocking orifice plate (104) and assign initial size according to experience; set multiple flow dividing fins (105) around inlet flow dividing groove (103), distribute original seed position of flow dividing fins (105) according to experience, and assign initial length, thickness and curvature; set the above optimization parameters, including the position, length, thickness and curvature of flow dividing fins (105), and the position and size of water permeable hole (1041), and set the uniformity of inlet flow dividing groove (103) and overall flow resistance as response variables; S4, calculate the steady state fluid distribution and overall pressure drop in solving domain using Navier-Stokes equation or its derived fluid dynamics control equation; after obtaining the steady state solution, compare the existing result with target uniformity and pressure drop, and use particle swarm algorithm and genetic algorithm to fill or delete the existing space structure once, generate new structure, and solve again; S5, repeat iteration step S4 until the uniformity of inlet flow dividing groove (103) and pressure drop target are reached, and the flow uniformity structure is completed.

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