A cold plate temperature control system and method with bifurcated flow channel coupled with a thermal storage medium

Abstract

The application discloses a cold plate temperature control system and method coupled with branched flow channels and heat storage medium, and relates to the field of battery thermal management. A 3-5 level branched channel network is opened in the battery cold plate substrate. The distance between adjacent levels of branched channels gradually decreases along the direction of the cooling medium from the inlet to the outlet. Each of the substrate solid areas between the two adjacent levels of branched channels is provided with a closed filling cavity. The filling cavity and the branched channel are not communicated with each other and are separated by a heat-conducting thin wall formed by the substrate body. A porous metal framework block is fixed in the cavity. The framework block is segmented into multiple sections along the flow direction. The porosity of each section gradually decreases along the flow direction, corresponding to the same direction of the gradually decreasing level distance. The application also provides a temperature control method using the cold plate and the temperature control circuit outside the plate. The cooling and heating modes are switched according to the temperature signal. The application synchronously enhances the heat exchange of the flow channel and the phase change heat storage capacity along the flow direction, has good plate surface uniformity, and can realize cooling peak cutting and heating valley filling.

Description

Technical Field

[0001] This invention relates to the field of battery thermal management technology, specifically to a cold plate temperature control system and method for a bifurcated flow channel coupled with a heat storage medium. Background Technology

[0002] With the rapid development of new energy vehicles and the energy storage industry, lithium-ion batteries have become the mainstream power source and energy storage carrier due to their high energy density, long cycle life, and low self-discharge rate. Batteries generate a large amount of heat under high-rate discharge and fast-charging conditions, requiring a thermal management system to control their temperature within a suitable range. In low-temperature environments, batteries need preheating to prevent lithium plating during charging and to ensure discharge capacity. Liquid cooling plates, due to their strong heat exchange capacity and compact structure, have become a core component of battery thermal management. The form of the internal flow channels of the cooling plate directly determines the temperature uniformity of the plate surface and the system energy consumption.

[0003] In terms of flow channel structure, bifurcated or tree-like flow channels are used to enhance heat transfer in cold plates due to their symmetrical flow and large heat transfer area. For example, there are reports of leaf vein bifurcated microchannel cold plates; there are also branched bifurcated variable cross-section liquid cooling plates, which are improved by gradually decreasing the width of the flow channel from the inlet to the outlet, and the spacing between the branch channels on the same side is the same; there are also battery cold plates that divide the flow direction into regions, so that the number of parallel flow channels increases along the flow path, and the increasing number of flow channels compensates for the temperature rise of the coolant along the flow path; and there are biomimetic leaf stem type flow channel cold plates, in which the angle between the branches and the main stem gradually decreases along the flow direction, so as to arrange more branch channels in the later section. The above schemes improve the heat transfer capacity of the cold plate along the flow path from the perspectives of variable cross-section, variable number of flow channels, and variable branch angle.

[0004] In the coupling of phase change thermal storage and liquid cooling, there are sandwich-type phase change material cold plates that combine phase change materials in a sandwich form with a liquid cooling structure; gradient melting point schemes that use phase change materials with different melting points arranged periodically and matched with liquid cooling pipes; systems that set phase change material filling cavities in the cold plate and configure water tanks and valve groups to achieve dual-mode switching; low-temperature heating devices that switch between radiator branches, phase change thermal storage branches and electric heaters through valves on the same cold plate and the same water pump, and control according to the two stages of phase change material melting and heat storage and solidification and heat release; and battery cooling devices that use welded sealed cavities filled with phase change materials to achieve dual-mode cooling and heat preservation. In terms of filling structure, there are phase change cold plates with porous carbon or foam metal as the skeleton, paraffin-like materials as the filling medium and a welded sealed cover plate, as well as phase change cold plates that are divided into multiple unit cavities in the box groove, with phase change blocks placed in each unit cavity and sealed. In academic research, there are also published documents reporting on gradient porosity foam metal and paraffin composite structures with decreasing porosity along the flow direction of the cooling medium, which have smaller temperature differences in battery packs than uniform porosity schemes.

[0005] It can be seen that in the prior art, the schemes for controlling the density of the bifurcation channels along the flow path and the schemes for controlling the porosity or filling density of the phase change skeleton along the flow path are proposed independently. There are no reports of coordinating the gradual densification of the bifurcation channel spacing and the gradient of the skeleton's heat storage capacity along the flow path in the same direction. At the same time, there are no reports of a structure in which the phase change material filling cavity is embedded in the substrate solid region between the bifurcation channel network and separated from the flow path by a thermally conductive thin wall formed by the substrate body. In addition, there is still room for further improvement in the bidirectional utilization of the phase change heat storage capacity in both the cooling peak shaving and the low-temperature valley filling directions. In view of this, this application is made.

[0006] In view of the above, this application is hereby submitted. Summary of the Invention

[0007] The technical problem to be solved by this invention is: addressing the issues of large instantaneous heat generation during battery fast charging, temperature differences along the flow direction of the liquid cooling plate and the difficulty in utilizing phase change heat storage media in low-temperature environments where battery preheating is required. This invention provides a cold plate temperature control system and method with bifurcated flow channels coupled with heat storage media, enabling the heat exchange capacity of the cold plate's flow channels and the phase change heat storage capacity to be synergistically matched along the flow direction, improving the temperature uniformity of the plate surface, and realizing bidirectional utilization of cooling peak shaving and heating valley filling.

[0008] The technical solution adopted by the present invention to solve its technical problem is: a cold plate temperature control system with bifurcated flow channel coupled heat storage medium is provided, the temperature control system includes a battery cold plate and an external temperature control circuit connected to the battery cold plate. The battery cooling plate includes a substrate with a multi-level branching channel network within it. The number of branching levels is 3 to 5. The branching channel network has an inlet for the cooling medium to flow in and an outlet for the cooling medium to flow out. Along the direction of the cooling medium flow from the inlet to the outlet, the spacing between adjacent branching channels gradually decreases. Each of the substrate solid areas between two adjacent branching channels is provided with a closed filling cavity. The filling cavity and the branching channel are not interconnected and are separated by a thermally conductive thin wall formed by the substrate body material. The filling cavities are arranged alternately with the branching channels at each level along the substrate surface. A porous metal skeleton block is fixed inside the filling cavity, and the pores of the skeleton are filled with an organic phase change heat storage medium. The porous metal skeleton block is divided into multiple segments along the flow direction of the cooling medium. The inlet segment uses a large-pore foam metal with high porosity, and the outlet segment uses a dense foam metal with low porosity. The porosity of each intermediate segment gradually decreases, so that the porosity gradient of the skeleton corresponds to the gradual decrease in the spacing between the branching levels along the same flow direction. The heat exchange capacity on the flow channel side and the heat storage capacity on the heat storage side are synchronously enhanced along the flow direction.

[0009] The external temperature control circuit includes a main supply pipe, a main return pipe, a circulating pump, a cooling branch, a heating branch, a commutation device, a temperature sensor, and a controller. The cooling branch and the heating branch are connected in parallel and selectively connected to the external temperature control circuit via the commutation device. The temperature sensor collects temperature signals, and the controller controls the commutation device to switch between the cooling branch and the heating branch based on the temperature signals. This invention also provides a battery cold plate constituting the above-described temperature control system, and a method for controlling the temperature of the cold plate using the above-described temperature control system.

[0010] Preferably, along the flow direction of the cooling medium, the spacing between adjacent bifurcation channels decreases according to an arithmetic or geometric law; when decreasing according to a geometric law, the spacing between the next bifurcation channel and the previous bifurcation channel is 0.6 to 0.9 times the spacing between the previous bifurcation channel and the bifurcation channel before that.

[0011] Preferably, each level of bifurcation channel is a Y-shaped two-way bifurcation channel, and the number of branches after each level of bifurcation channel is twice that before the bifurcation. The number of branches of the nth level bifurcation channel is 2 to the power of n. There is a direct current channel between adjacent levels of bifurcation channels, and there are straight channels between the inlet and the first level bifurcation channel and between the last level bifurcation channel and the outlet.

[0012] Preferably, along the flow direction of the cooling medium from inlet to outlet, the porosity of the porous metal skeleton block decreases from 90% to 95% to 60% to 75%, and the filling density of the phase change heat storage medium increases in the opposite direction along the flow direction.

[0013] Preferably, the thickness of the thermally conductive thin wall is 0.5 mm to 3 mm; the porous metal skeleton block is made of foamed aluminum, foamed copper or sintered metal porous material, and is fixed in the filling cavity by interference fit or bonding.

[0014] Preferably, the organic phase change heat storage medium is a paraffin-based phase change material with a phase change temperature of 20°C to 40°C; the cavity opening is sealed by a cover plate, and the cover plate and the substrate are sealed together by vacuum brazing or friction stir welding.

[0015] Preferably, the cooling branch includes an air-cooled radiator and a fan that drives airflow through the air-cooled radiator, or the cooling branch includes a plate heat exchanger that exchanges heat with the vehicle's air conditioning refrigerant circuit.

[0016] Preferably, the heating branch includes a PTC electric heater, which is connected in series in the heating branch to heat the cooling medium.

[0017] Preferably, the reversing device is any one of the following three options: an interlocked electric two-way valve is provided on each of the cooling branch and the heating branch; an electric three-way valve is provided on the main supply pipe or the main return pipe with two branch interfaces respectively connected to the two branches; or a four-way reversing valve is provided in the circuit to allow one of the two branches to be connected by reversing.

[0018] Preferably, a circulating pump is arranged in the plate external temperature control loop, the loop is filled with a single cooling medium, and the cooling medium is ethylene glycol antifreeze solution; an expansion tank is connected to the common pipe section on the inlet side of the circulating pump.

[0019] Preferably, the temperature sensor is attached to the surface of the battery or the surface of the cold plate; the controller is a battery management system or an independent temperature controller; and the circulating pump is a variable pump with adjustable rotating speed.

[0020] Preferably, the bifurcated channel network comprises first, second, third, fourth and fifth bifurcated channels connected in sequence, and adjacent two levels are connected through inter-bifurcated direct channels.

[0021] Preferably, the cold plate is at least two and is attached to the opposite sides of the battery in pairs, the inlet of each cold plate is connected to the main flow channel, the main flow channel has a main flow channel inlet and a main flow channel outlet, the outlet of each cold plate is connected to the main flow channel outlet, and the main flow channel is connected in series in the plate external temperature control loop.

[0022] Preferably, the filling cavity is a plurality of, and the plurality of filling cavities and the bifurcated channels of each level are alternately arranged along the surface of the substrate, and each filling cavity is located in the substrate solid region between adjacent bifurcated channels and / or inter-bifurcated direct channels.

[0023] The application also provides a cold plate temperature control method of bifurcated flow channel coupled with heat storage medium, comprising the following steps:

[0024] S1, collecting the temperature signal of the battery or the cold plate by the temperature sensor and transmitting it to the controller.

[0025] S2, when the temperature is greater than or equal to the upper threshold value, the controller controls the reversing device to connect the cooling branch to the loop, the system enters the cooling mode, the circulating pump drives the cooling medium to flow in the bifurcated channel network to absorb heat, the phase change heat storage medium in the filling cavity absorbs the peak heat of the battery and melts to store heat, and the gradually decreasing bifurcated level spacing and the skeleton porosity decreasing in the same direction compensate for the heat transfer temperature difference attenuation caused by the temperature rise of the cooling medium along the flow direction.

[0026] S3, when the temperature is less than or equal to the lower threshold value, the controller controls the reversing device to connect the heating branch to the loop, the system enters the heating mode, the heating mode includes the heating stage and the heat preservation stage, in the heating stage, the heated cooling medium flows through the bifurcated channel network to release heat and melt the phase change heat storage medium, the gradually decreasing level spacing and the skeleton porosity decreasing in the same direction compensate for the heat transfer temperature difference caused by the temperature drop of the heating medium along the flow direction, in the heat preservation stage, the circulating pump and the heating branch stop working, the phase change heat storage medium solidifies to release heat, and the heat is slowly released through the porous metal skeleton block and the heat-conducting thin wall to heat the battery.

[0027] S4. When the temperature is between the lower and upper thresholds, the circulation pump stops or runs at a low flow rate, and the system goes into standby mode.

[0028] Preferably, the upper threshold is 35°C and the lower threshold is 5°C, and the battery temperature is maintained at around 15°C during the heat preservation stage.

[0029] Preferably, the melting is considered complete when the temperature of the cooling medium or the cold plate reaches the upper limit of the phase change temperature of the phase change heat storage medium and is maintained for a set time during the heat charging stage, and then the process transitions to the heat preservation stage. During the heat preservation stage, the heat charging is restarted when the temperature drops to the restart temperature. In the cooling mode, the fan speed of the air-cooled radiator increases in tandem with the increase of the temperature of the cooling medium.

[0030] The beneficial effects of this invention are:

[0031] 1. The spacing between adjacent bifurcation channels gradually decreases along the flow direction, which increases the heat exchange area of ​​the channel wall per unit length in the rear section of the cold plate. This compensates for the attenuation of heat exchange temperature difference caused by the temperature rise (cooling mode) or temperature drop (heating mode) of the cooling medium along the flow path. This feature is symmetrically effective in both cooling and heating modes.

[0032] 2. The porosity and / or the density of the phase change heat storage medium in the porous metal skeleton block are distributed in a gradient along the flow direction, and the gradient direction is consistent with the direction of the gradual increase in the interstage spacing. This makes the heat transfer capacity on the flow channel side and the heat storage capacity on the heat storage side simultaneously enhanced along the flow direction. The two gradients work together, and the temperature uniformity of the plate surface is better than that of the single gradient scheme.

[0033] 3. The filling cavity is embedded in the substrate solid area between the bifurcated channels. The thermally conductive thin wall formed by the substrate body is separated from the flow channel. The heat transfer path between the heat storage medium and the cooling medium is short and the response is fast. Moreover, the filling cavity and the flow channel are not interconnected, so there is no risk of liquid cross-contamination.

[0034] 4. The external temperature control circuit adopts a single circulation pump, single working fluid and parallel dual branch switching architecture, with fewer components and simpler control, and is structurally simpler than the multi-tank and multi-pump scheme.

[0035] 5. The heating mode is divided into two stages: heat charging and heat preservation. The phase change heat storage medium reduces peaks during cooling and fills valleys during heating, making bidirectional use. During the heat preservation stage, neither the pump nor the heater works, reducing the frequency of PTC start-stop and system energy consumption. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the overall structure of the cold plate provided in an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the bifurcated channel network and filling cavity arrangement after removing the cover plate, provided in an embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of the cross-sectional structure of the filling cavity provided in an embodiment of the present invention.

[0039] Figure 4 This is a schematic diagram of the curves showing the dual gradient distribution of porosity and thermal storage medium filling density along the flow direction for the porous metal skeleton block provided in an embodiment of the present invention.

[0040] Figure 5 This is a schematic diagram of an external temperature control circuit system provided in an embodiment of the present invention.

[0041] Figure 6 The diagram shows three commutation device schemes provided in the embodiments of the present invention.

[0042] Figure 7 This is a flowchart illustrating the heating mode's charging and heat preservation stages as provided in an embodiment of the present invention.

[0043] Figure 8 This is a schematic diagram of the cold plate being assembled with the main flow equalization channel inside the battery pack, as provided in an embodiment of the present invention.

[0044] Explanation of reference numerals in the attached diagram: 1. Cold plate; 101. Inlet; 102. Outlet; 103. Heat storage medium zone; 1031. Porous metal skeleton block; 1032. Heat storage medium; 104. Straight channel; 105. First-stage bifurcation channel; 106. Second-stage bifurcation channel; 107. Third-stage bifurcation channel; 108. Fourth-stage bifurcation channel; 109. Fifth-stage bifurcation channel; 110. Direct current channel between bifurcations; 2. Battery; 201. Electrode; 3. Main flow equalization channel; 301. Main flow equalization channel. 302. Main flow channel inlet; 4. Liquid supply main pipe; 5. Liquid return main pipe; 6. Circulation pump; 7. Cooling branch; 71. Air-cooled radiator; 72. Fan; 73. Plate heat exchanger; 8. Heating branch; 81. PTC electric heater; 9. Reversing device; 91. Electric two-way valve A; 92. Electric two-way valve B; 10. Expansion tank; 11. Temperature sensor; 12. Controller; 13. Cover plate; 14. Filling cavity; 15. Thermally conductive thin wall. Detailed Implementation

[0045] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0046] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in this application and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or," as used herein, refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0047] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with specific embodiments.

[0048] In some embodiments of the present application, a cold plate temperature control system is provided, which includes a cold plate 1 and an off-plate temperature control circuit. The cold plate 1 includes a substrate, and a multi-stage branched channel network is formed in the substrate. The branched channel network has 3 to 5 stages of branching, and has an inlet 101 for the cooling medium to flow in and an outlet 102 for the cooling medium to flow out. The distance between adjacent stages of branched channels gradually decreases in the direction of the cooling medium flowing from the inlet 101 to the outlet 102. A closed filling cavity 14 is formed in the solid area of the substrate between the branched channels, and the filling cavity 14 and the branched channels are not in communication with each other, and are separated by a heat-conducting thin wall 15 formed by the substrate material. A porous metal framework block 1031 is fixed in the filling cavity 14, and the pores of the porous metal framework block 1031 are filled with a phase change heat storage medium 1032. The porosity of the porous metal framework block 1031 and / or the filling density of the phase change heat storage medium 1032 are gradiently distributed in the direction of the cooling medium flow, and the gradient change direction is consistent with the direction of the gradually decreasing distance between adjacent stages of branched channels. The off-plate temperature control circuit includes a liquid supply main pipe 4, a liquid return main pipe 5, a circulating pump 6, a cooling branch 7, a heating branch 8, a switching device 9, a temperature sensor 11 and a controller 12. The cooling branch 7 and the heating branch 8 are connected in parallel between the liquid supply main pipe 4 and the liquid return main pipe 5, and are selectively connected to the circuit through the switching device 9. The controller 12 controls the switching device 9 to switch according to the temperature signal.

[0049] In the implementation process, the base plate of the cold plate 1 is made of a metal material with good thermal conductivity, such as 3003 or 6061 aluminum alloy. The flow channel groove and the cavity groove can be milled on the upper and lower plate bodies respectively, and then the two plate bodies are overlapped and vacuum brazed. Alternatively, the cold plate can be manufactured by using an extruded profile in combination with milling and friction stir welding. The bifurcated channel network is distributed on the base plate in the form of leaf veins. The inlet 101 is arranged at one end of the base plate, and the outlet 102 is arranged at the other end of the base plate. The cooling medium enters the straight channel 104 from the inlet 101, flows through each level of bifurcated channels in sequence, and then flows out from the outlet 102. The filling cavity 14 is provided with a groove in the solid area between adjacent channels when the flow channel groove is processed. The groove bottom and groove wall are the heat-conducting thin walls 15 separated from the flow channel. The prefabricated porous metal skeleton block 1031 is fixed in the groove, and then the molten phase change heat storage medium 1032 is vacuum filled. After the phase change heat storage medium 1032 seeps into the skeleton pores, the cover plate 13 is used to seal and weld the cavity opening. As shown in Figure 5 In the plate external temperature control circuit, the liquid supply main pipe 4 distributes the cooling medium to each cold plate 1, the liquid return main pipe 5 collects the return water of each cold plate 1, the cooling branch 7 is used to dissipate the heat of the circuit, the heating branch 8 is used to increase the temperature of the medium in the circuit, and the two branches are arranged in parallel and are selectively connected by the reversing device 9. The temperature sensor 11 is attached to the surface of the battery 2 or the cold plate 1 to collect the temperature. The controller 12 issues control instructions to the reversing device 9, the circulating pump 6, and the branch components according to the preset threshold value.

[0050] By using the above technical scheme, the interval between the levels gradually decreases along the flow direction, so that the channel heat exchange area per unit length of the rear section of the cold plate increases. The skeleton porosity and the filling density of the heat storage medium change gradiently along the same direction, so that the heat storage density of the rear section of the cold plate increases synchronously. The flow channel heat exchange and the phase change heat storage are synergistically enhanced along the flow direction. The filling cavity and the flow channel are separated by the body thin wall, the heat transfer path is short, and the liquids do not mix with each other. The plate external circuit switches the temperature by using the parallel double branch, and the cooling and heating conditions share the same cold plate and the same medium. The system is simple in structure.

[0051] In some preferred embodiments of the present application, the interval between adjacent bifurcated channels decreases according to an arithmetic progression or a geometric progression along the flow direction of the cooling medium. When the interval decreases according to a geometric progression, the interval between the bifurcated channel of the rear level and the bifurcated channel of the front level is 0.6 to 0.9 times the interval between the bifurcated channel of the front level and the bifurcated channel of the level before the front level.

[0052] In the specific implementation process, the distance between the first-level branch channel and the second-level branch channel is d1, and the distances of subsequent levels are d2, d3, and d4 respectively. When decreasing according to an arithmetic progression, the distances between adjacent levels differ by a fixed difference Δd, i.e., d2 = d1 - Δd, d3 = d2 - Δd, d4 ​​= d3 - Δd; when decreasing according to a geometric progression, d2 = q·d1, d3 = q·d2, d4 = q·d3, where the common ratio q is selected between 0.6 and 0.9, preferably between 0.75 and 0.85. The spacing sequence is determined during the cold plate flow channel layout design and is formed in one step during processing through a milling program or extrusion die, without the need for additional components. When the common ratio q is less than 0.6, the subsequent channel arrangement is too dense, and the flow resistance increases rapidly; when q is greater than 0.9, the gradual decrease is insufficient, and the effect of compensating for the temperature difference along the flow path is not obvious. For cold plates with 3 to 5 bifurcations, when designed according to the above range, the interstage spacing near the last stage is about 0.3 to 0.6 times that of the first stage, and the channel density of the outlet section is significantly higher than that of the inlet section.

[0053] By adopting the above technical solution, the gradual reduction law of the stage spacing is clear and quantifiable, which makes it easy for designers to directly lay out according to the length of the cold plate and the heat exchange requirements; the magnitude of the proportional reduction gradually increases along the flow direction, which matches the trend of the near exponential change of the cooling medium temperature along the flow path, and allows the heat exchange area of ​​the later stage to be strengthened in a targeted manner under the condition of limited increase in flow resistance.

[0054] In some preferred embodiments of this application, each level of bifurcation channel is a Y-shaped two-way bifurcation channel. After each level of bifurcation, the number of channel branches is twice that before the bifurcation, and the number of branches of the nth level bifurcation channel is 2 to the power of n. Adjacent level bifurcation channels are connected by inter-bifurcation DC channels 110, and straight channels 104 are connected between the inlet 101 and the first level bifurcation channel, as well as between the last level bifurcation channel and the outlet 102.

[0055] In practical implementation, the two branches of the Y-shaped bifurcation are arranged symmetrically about the direction of incoming flow. The angle between the two branches at the bifurcation point can be 30 to 60 degrees, allowing the flow to smoothly separate at the bifurcation point. The direct current channel 110 between the bifurcation points connects the ends of each branch of the previous stage with the bifurcation node of the next stage, rectifying and equalizing the incoming flow to prevent the velocity distribution from becoming skewed after the bifurcation. The cross-section of the straight channel 104 and the bifurcation channel can be rectangular or circular, with a hydraulic diameter of 1 mm to 5 mm. Each channel is arranged at the same depth within the substrate. Taking a 5-stage bifurcation as an example, the number of branches at each stage is 2, 4, 8, 16, and 32, respectively. The end of the final branch flows into the outlet cavity through the straight channel for confluence and then flows out through the outlet 102, thus forming a symmetrical network of "step-by-step bifurcation and step-by-step confluence". The number of bifurcation stages can also be 3 or 4, selected according to the length of the cold plate along the flow direction and the total heat exchange area requirement.

[0056] Using the above technical solution, the Y-shaped bifurcation structure has symmetrical flow and uniform flow distribution among branches; the direct current channel between branches suppresses eddies and deflections at the bifurcation points, reducing the overall pressure drop of the network; the number of branches increases with the number of stages and the spacing between stages gradually decreases, so that the rear section of the cold plate can be improved in terms of both the number of channels and the arrangement density, and the heat exchange area density is greatly increased.

[0057] In some preferred embodiments of this application, along the flow direction of the cooling medium from inlet 101 to outlet 102, the porosity of the porous metal skeleton block 1031 decreases from 90% to 95% to 60% to 75%, and the filling density of the phase change heat storage medium 1032 increases in the opposite direction along the flow direction.

[0058] In the specific implementation process, the porous metal skeleton block 1031 can be composed of multiple sections of foam metal blocks with different porosities spliced ​​along the flow direction: the inlet section uses large-pore foam with a porosity of 90% to 95%, such as aluminum foam with a porosity of 10 PPI to 20 PPI; the outlet section uses dense foam with a porosity of 60% to 75%, such as small-pore copper foam with a porosity of 40 PPI or above, or pressed sintered metal; the porosity of each intermediate section gradually transitions, and the skeleton block is pressed or bonded into the filling cavity 14 as a whole. The skeleton block can also be made into a continuously variable porosity blank by integral foaming followed by segmented compression, or by gradient powder spreading and sintering. After the skeleton is fixed, molten paraffin-based heat storage medium is poured into the cavity under vacuum conditions, so that the medium fully penetrates the skeleton pores; after the pouring solidifies, the mass of the heat storage medium per unit volume is the filling density. The outlet section, with its low porosity, has a high proportion of metal skeleton, resulting in greater thermal conductivity and sensible heat capacity. The latent heat of phase change per unit volume that can participate in buffering is also increased as designed. The inlet section, with its high porosity, has a large proportion of medium volume, resulting in a large total heat storage and low flow resistance. The packing density increases in reverse order, meaning that the heat storage capacity per unit volume gradually increases along the flow direction.

[0059] Using the above technical solution, the inlet section has a low cooling medium temperature and a large heat exchange temperature difference. The high porosity skeleton combined with a large-capacity heat storage medium can meet the heat exchange and peak shaving requirements of this section. The outlet section has a high cooling medium temperature and a small heat exchange temperature difference. The dense skeleton enhances thermal conductivity, and the higher filling density provides more latent heat buffer. It is consistent with the direction of the gradually decreasing interstage spacing, so that the heat exchange gradient on the flow channel side and the heat storage gradient on the heat storage side are superimposed in the same direction, and the plate surface temperature distribution is further flattened.

[0060] In some preferred embodiments of this application, the thickness of the thermally conductive thin wall 15 is 0.5 mm to 3 mm; the porous metal skeleton block 1031 is made of foamed aluminum, foamed copper or sintered metal porous material, and is fixed in the filling cavity 14 by interference fit or bonding.

[0061] In the specific implementation process, the thermally conductive thin wall 15 is a solid partition wall retained by the substrate body between the filling cavity 14 and the adjacent branched channels. When milling the cavity groove on the substrate, the thickness of the groove bottom and groove wall is controlled between 0.5mm and 3mm, preferably 1mm to 2mm. If the wall thickness is too small, it is easy to mill through during processing and the pressure resistance is insufficient. If the wall thickness is too large, the thermal resistance of the partition wall increases and the response slows down. For aluminum alloy substrates, when the wall thickness is within 2mm, its thermal resistance can be ignored relative to the thermal resistance of the heat storage medium side. The porous metal skeleton block 1031 is prefabricated according to the shape of the filling cavity 14, with an interference allowance of 0.1mm to 0.3mm in its outer dimensions, and is pressed into the cavity and fixed by elastic clamping; alternatively, thermally conductive structural adhesive can be used for bonding, and the adhesive layer simultaneously fills the microscopic gap between the skeleton and the cavity wall. Foamed aluminum has low density and low cost, making it suitable for general operating conditions; foamed copper has a higher thermal conductivity, making it suitable for outlet sections with higher heat flux densities; sintered porous metal materials can be made into gradient blanks with continuously varying porosity along the flow direction, suitable for applications with strict gradient requirements. The skeleton block also constrains the heat storage medium within the cavity, preventing macroscopic flow after the medium melts and is adsorbed in the pores.

[0062] Using the above technical solution, the thermally conductive thin wall provides a low thermal resistance heat transfer interface while ensuring that the flow channel and the filling cavity are not interconnected; the skeleton block is reliably fixed, and the heat storage medium does not flow or form voids in the cavity during repeated melting and solidification, thus ensuring the thermal conductivity and long-term cycle stability of the composite structure.

[0063] In some preferred embodiments of this application, the organic phase change heat storage medium 1032 is a paraffin-based phase change material with a phase change temperature of 20°C to 40°C; the cavity opening of the filling cavity 14 is sealed by a cover plate 13, and the cover plate 13 and the substrate are sealed together by vacuum brazing or friction stir welding.

[0064] In practical implementation, paraffin-based phase change materials can be ordinary paraffin, modified paraffin, or a composite wax of paraffin and fatty acids. The melting point should be selected according to the optimal operating temperature range of the battery: for high-temperature cooling and peak reduction, a grade with a melting point of 30℃ to 35℃ can be selected; for low-temperature heat preservation, a grade with a melting point of 20℃ to 25℃ can be selected. If necessary, a small amount of expanded graphite or metal powder can be added to the paraffin to assist in heat conduction, while the main heat conduction enhancement is undertaken by the porous metal skeleton. The cover plate 13 is made of aluminum alloy thin plate of the same material as the substrate and is placed on the step reserved at the cavity opening. Vacuum brazing can be completed in the same furnace as the composite of the upper and lower flow channel plates, resulting in dense welds suitable for mass production. Friction stir welding is a solid-state welding method with low heat input and small deformation, suitable for sealing each cavity on a large plate. The heat storage medium can be injected before sealing, or a liquid injection hole can be reserved on the cover plate, and after welding, vacuum injection can be carried out through the liquid injection hole before sealing.

[0065] Using the above technical solution, paraffin-based media have a large latent heat, low supercooling, stable chemical properties, wide availability, and low cost; welding and sealing make the filling cavity a fully enclosed cavity, so that the heat storage medium does not leak, oxidize, or absorb water, and its service life is consistent with that of the cold plate body.

[0066] In some preferred embodiments of this application, the cooling branch 7 includes an air-cooled radiator 71 and a fan 72 that drives air to flow through the air-cooled radiator 71; or, the cooling branch 7 includes a plate heat exchanger 73 that exchanges heat with the vehicle air conditioning refrigerant circuit.

[0067] In practical implementation, when using the air-cooled solution, the air-cooled radiator 71 is an automotive aluminum tube-and-strip or stacked radiator, connected in series on the cooling branch between the supply main pipe 4 and the return main pipe 5. The fan 72 is located on one side of the radiator and its speed is adjusted by the controller 12. The cooling medium dissipates heat to the ambient air within the radiator. This solution is suitable for driving conditions with moderate ambient temperature and moderate heat dissipation requirements. When using the plate heat exchanger 73 (i.e., the chiller), the cooling medium flows through a loop on one side of the heat exchanger, while the low-temperature refrigerant output from the evaporator of the vehicle's air conditioning system flows on the other side. The cooling medium is cooled to near or even below the ambient temperature by absorbing heat through refrigerant evaporation. This solution is suitable for high-power heat dissipation during fast charging and high-temperature environmental conditions. Either solution can be selected or configured simultaneously in the same system, selected or used in series by the controller 12 according to the operating conditions.

[0068] The above technical solutions offer advantages such as simple structure, low cost, and easy maintenance for air-cooled systems, and strong cooling capacity and low lower limit of cooling medium temperature, which can cover fast charging and high-temperature scenarios. The system can be flexibly selected according to vehicle model positioning.

[0069] In some preferred embodiments of this application, the heating branch 8 includes a PTC electric heater 81, which is connected in series in the heating branch 8 and heats the cooling medium in the circuit.

[0070] In practical implementation, the PTC electric heater 81 adopts a vehicle-grade positive temperature coefficient water heater, and its heating power is selected according to the low-temperature heating requirements of the battery pack. The heater body is connected in series in the pipe section of the heating branch 8, and the circulating pump 6 drives the cooling medium to flow through the heated surface and be heated. The PTC element has a self-limiting temperature characteristic that the resistance increases with the temperature, so it will not heat up indefinitely even if the control fails. The heating branch 8 is only energized and operates during the charging phase of the heating mode. During the heat preservation phase, the PTC electric heater 81 and the circulating pump 6 stop together.

[0071] Using the above technical solution, PTC heating has a fast response, simple temperature control, and good inherent safety. Since the phase change heat storage medium stores a large amount of latent heat during the charging stage and releases it slowly during the heat preservation stage, PTC does not need to run continuously throughout the low temperature period, and its start-stop frequency and cumulative energy consumption are significantly reduced.

[0072] In some preferred embodiments of this application, the reversing device 9 is any one of the following three schemes: Scheme 1, each of the cooling branch 7 and the heating branch 8 is provided with an electric two-way valve 91 and 92, and the two electric two-way valves are interlocked to open and close; Scheme 2, the liquid supply main pipe 4 or the liquid return main pipe 5 is provided with an electric three-way valve, and the two branches of the electric three-way valve are respectively connected to the cooling branch 7 and the heating branch 8; Scheme 3, the external temperature control circuit is provided with a four-way reversing valve, and the four-way reversing valve connects the cooling branch 7 or the heating branch 8 to the circuit by reversing.

[0073] In the specific implementation process, in Scheme 1, the electric two-way valve 91 is connected in series in the cooling branch 7, and the electric two-way valve 92 is connected in series in the heating branch 8. The controller 12 controls the two valves to open and close, and sets an electrical interlock. When cooling is needed, valve 91 is open and valve 92 is closed; when heating is needed, the opposite is true. The structure is simple and the cost is low. In Scheme 2, the common interface of the electric three-way valve is connected to the main supply pipe 4 or the main return pipe 5. The two branch interfaces are connected to the two branches respectively. The opening ratio of the two branches is changed by the valve core rotation angle. In addition to full switching, a small-ratio mixed flow can also be achieved, and the transition is smoother. In Scheme 3, the four-way reversing valve completes the on / off switching of the two branches in one reversal. The number of pipes is minimized and the switching action is fast. All three reversing devices are installed on the external pipes of the plate, without changing the flow channel and filling cavity structure inside the cold plate 1.

[0074] Using the above technical solutions, the specific form of the reversing device can be selected according to the vehicle's thermal management architecture and cost targets. The two-way interlocking scheme is economical, the three-way scheme has proportional adjustment capability, and the four-way scheme has rapid switching, simple piping, and the system is not sensitive to valve type and has strong adaptability.

[0075] In some preferred embodiments of this application, an external temperature control circuit is provided with a circulating pump 6, and the circuit is filled with a single cooling medium, namely ethylene glycol antifreeze; an expansion tank 10 is connected to the common pipe section on the inlet side of the circulating pump 6.

[0076] In practical implementation, the cooling mode and heating mode share the same circulating pump 6 and the same cooling medium. The circulating pump 6 is an automotive electric centrifugal water pump, connected in series on a common pipe section before the main supply pipe 4. The concentration of ethylene glycol antifreeze is selected according to the lowest ambient temperature; for example, when the ambient temperature is as low as -25°C, an ethylene glycol aqueous solution with a volume fraction of approximately 50% can be used. The expansion tank 10 is connected to the common pipe section on the suction side of the circulating pump 6. It is used to accommodate the expansion volume of the cooling medium after heating, compensate for the contraction of the medium, and serve as an interface for system water injection and venting. A liquid level sensor can be installed in the tank to indicate liquid replenishment. The main supply pipe 4 and the main return pipe 5 are common headers connecting all the cold plates 1 in parallel.

[0077] The above technical solution reduces the number of circuit components, lowers costs, and simplifies control logic, significantly simplifying the structure compared to solutions with multiple hot water storage tanks and multiple pumps. The expansion tank ensures stable pump inlet pressure, prevents cavitation, and buffers system pressure changes with temperature.

[0078] In some preferred embodiments of this application, the temperature sensor 11 is attached to the surface of the battery 2 or the surface of the cold plate 1; the controller 12 is a battery management system or an independent temperature controller; and the circulation pump 6 is a variable pump with adjustable speed.

[0079] In the specific implementation process, the temperature sensor 11 adopts an NTC thermistor or a PT100 platinum resistance thermometer, which can be arranged at multiple points within the battery module, and the highest or average temperature is used as the control basis. The sensor probe is attached to the surface of the large surface of the battery 2 or the substrate of the cold plate 1, and thermal grease is applied at the contact point to reduce the contact thermal resistance. The controller 12 can be directly converted into the battery management system (BMS), using its existing battery temperature, state of charge, and state of charge information to make thermal management decisions, or an independent temperature controller can be used. The circulating pump 6 adopts an adjustable speed electronic water pump. In cooling mode, it runs at high speed when the medium temperature is high and at low speed when the temperature is close to the lower limit. In standby mode, it runs at a small flow rate or stops. During the heating and charging stage, the flow rate is adjusted according to the melting rate of the heat storage medium. The controller 12 is electrically connected to the commutation device 9, the fan 72, the PTC electric heater 81, and the circulating pump 6.

[0080] By adopting the above technical solution, the temperature acquisition location is close to the controlled object, and the control basis is accurate; the pump speed is adjusted according to the operating conditions to match the flow rate with the heat exchange demand, avoiding the ineffective energy consumption of the fixed speed pump under low demand conditions and reducing the parasitic power consumption of the system.

[0081] In some preferred embodiments of this application, the branch channel network includes a first-level branch channel 105, a second-level branch channel 106, a third-level branch channel 107, a fourth-level branch channel 108, and a fifth-level branch channel 109 connected in sequence, and adjacent branch channels are connected by a branch DC channel 110.

[0082] In the specific implementation process, the cooling medium enters the first-stage bifurcation channel 105 from the inlet 101 via the straight channel 104, where it splits into two at the first-stage bifurcation node. The two branches are then transported to the bifurcation node of the second-stage bifurcation channel 106 via the inter-bifurcation direct current channel 110, where they each split into two again. This process continues through the third-stage bifurcation channel 107, the fourth-stage bifurcation channel 108, and finally the fifth-stage bifurcation channel 109, resulting in a total of 32 branches across five stages. Each stage of the bifurcation channel is arranged sequentially along the flow direction, with the spacing between adjacent stages (d1, d2, d3, d4) decreasing sequentially (d1 > d2, d2 > d3, d3 > d4). The ends of the fifth-stage branches converge into the outlet cavity via a straight channel for merging and exit through the outlet 102. The bifurcation channels, the inter-bifurcation direct current channel 110, and the straight channel 104 are arranged on the same plane of the substrate, collectively forming a blade-like cross-linked bifurcation network. When the number of branching levels is 3 or 4, the flow path organization is the same, only the total number of branches and the network density are different.

[0083] Using the above technical solution, the total area of ​​the channel wall of the five-level branching network is large and the coverage of the plate surface is uniform; the direct current channel between the branches ensures that the flow is fully developed before each branch and that the flow rate of each branch is equal; the gradually decreasing inter-level spacing makes the five-level area with the densest channel correspond exactly to the outlet section with the highest temperature of the cooling medium, and the position of heat exchange compensation corresponds to the position of temperature difference attenuation.

[0084] In some preferred embodiments of this application, there are at least two cold plates 1, which are attached to each other on opposite sides of the battery 2. The inlet 101 of each cold plate 1 is connected to the main flow equalization channel 3. The main flow equalization channel 3 has a main flow equalization channel inlet 301 and a main flow equalization channel outlet 302. The outlet 102 of each cold plate 1 is connected to the main flow equalization channel outlet 302. The main flow equalization channel 3 is connected in series in the external temperature control circuit.

[0085] In the specific implementation process, battery 2 is a square lithium-ion cell with electrodes 201 at its top and bottom ends respectively. A cold plate 1 is attached to each of the two large surfaces of each cell, with thermally conductive structural adhesive or a thermally conductive pad applied between the cold plate surface and the cell surface to form a symmetrical heat exchange structure. The main flow equalization channel 3 is a header or distribution chamber spanning the battery module. After the cooling medium enters through the inlet 301 of the main flow equalization channel, it is evenly distributed to the inlets 101 of each cold plate 1. The return water from the outlets 102 of each cold plate 1 flows into the outlet 302 of the main flow equalization channel, and then returns to the cooling branch 7 or heating branch 8 of the external temperature control circuit via the return manifold 5. The flow cross-section of the main flow equalization channel 3 is designed according to the number of parallel cold plates, ensuring that the pressure at the inlet of each cold plate 1 is basically the same.

[0086] By adopting the above technical solution, the double-sided plate arrangement allows both large surfaces of the cell to participate in heat exchange simultaneously, resulting in a small temperature gradient in the cell thickness direction. The main flow equalization channel ensures consistent flow distribution among the parallel cold plates in the module, avoiding temperature differences between individual cells caused by uneven flow, which is beneficial to the consistency and cycle life of the assembled batteries.

[0087] In some preferred embodiments of this application, there are multiple filling cavities 14, and the multiple filling cavities 14 are arranged alternately with the various levels of branch channels along the surface of the substrate. Each filling cavity 14 is located in the substrate body area between adjacent branch channels and / or inter-branch DC channels 110.

[0088] In the specific implementation process, on the spread surface of the substrate, the branched channel network and the filling cavities 14 are arranged in an alternating array of "channel-cavity-channel": a filling cavity 14 is opened in the solid area between every two adjacent channels or two adjacent clusters of channels. The planar shape of the cavity is determined by the shape of the solid area and can be elongated, spindle-shaped, or rhomboid. Along the flow direction, the channels in the outlet section are densely arranged, and the filling cavities 14 are correspondingly narrow and dense; the channels in the inlet section are sparsely arranged, and the filling cavities 14 are wide and sparse. Each filling cavity 14 can be sealed by its own cover plate 13, or it can be sealed by a single integral cover plate 13. The porosity of the skeleton block in each cavity takes a gradient value according to the flow direction position of the cavity, so that the porosity of the entire plate skeleton changes continuously and gradually along the flow direction.

[0089] Using the above technical solution, the filling cavity is embedded between the flow channels, and the heat storage medium is separated from the nearest channel by only a thin thermally conductive wall 15. The heat transfer distance between the heat storage medium and the cooling medium is very short everywhere, and the response speed of heat storage and heat extraction is fast. The alternating array enables the battery heat at any position on the plate to be absorbed by the heat storage medium or carried away by the cooling medium nearby, and there is no heat exchange dead zone.

[0090] In some embodiments of this application, a cold plate temperature control method is provided, using the aforementioned cold plate temperature control system. The method includes steps S1 to S4. S1: The temperature signal of the battery 2 or the cold plate 1 is acquired by the temperature sensor 11 and transmitted to the controller 12. S2: When the temperature corresponding to the temperature signal is greater than or equal to the upper limit threshold, the controller 12 controls the reversing device 9 to connect the cooling branch 7 to the external temperature control circuit, and the system enters the cooling mode. The circulating pump 6 drives the cooling medium to flow and absorb heat in the bifurcation channel network. The phase change heat storage medium 1032 in the filling cavity 14 absorbs the peak heat of the battery 2 and melts and stores heat. The gradually decreasing spacing between adjacent bifurcation channels along the flow direction, together with the porosity of the porous metal skeleton block 1031 and / or the filling density of the phase change heat storage medium 1032 that varies in the same direction, jointly compensate for the attenuation of the heat transfer temperature difference caused by the temperature rise of the cooling medium along the flow path. S3. When the temperature corresponding to the temperature signal is less than or equal to the lower threshold, the controller 12 controls the reversing device 9 to connect the heating branch 8 to the external temperature control circuit, and the system enters the heating mode. The heating mode includes a charging stage and a heat preservation stage. In the charging stage, the heated cooling medium flows through the bifurcated channel network to release heat, causing the phase change heat storage medium 1032 to melt and store heat. The gradually decreasing interstage spacing and the unidirectional gradient distribution of skeleton porosity and / or filling density compensate for the heat transfer temperature difference attenuation caused by the temperature drop along the heating medium. In the heat preservation stage, the circulating pump 6 and the heating branch 8 stop working, the phase change heat storage medium 1032 solidifies and releases heat, and the heat is slowly released through the porous metal skeleton block 1031 and the thermally conductive thin wall 15 to heat the battery 2. S4. When the temperature corresponding to the temperature signal is between the lower threshold and the upper threshold, the circulating pump 6 stops running or runs at a small flow rate, and the system is in standby mode.

[0091] In the specific implementation process, the heat generated by battery 2 in cooling mode is first transferred to the filling cavity 14 through the substrate and thermally conductive thin wall 15. Some of the heat is absorbed by the phase change heat storage medium 1032 in the form of latent heat of fusion, and the instantaneous large heat flow such as fast charging is smoothed out. At the same time, the cooling medium in the branch channel continuously carries the heat to the external cooling branch 7 for dissipation. After the heat flow returns, the heat storage medium solidifies and the heat storage capacity is restored. As the cooling medium continuously absorbs heat along the way and the temperature gradually increases, the heat exchange temperature difference in the inlet section is large and the heat exchange temperature difference in the outlet section is small. The gradually decreasing interstage spacing makes the outlet section channel denser and the heat exchange area larger. The decreasing porosity of the skeleton and the increasing filling density make the heat storage density in the outlet section greater. The two gradients act in the same direction, smoothing out the temperature difference between the inlet and outlet sections of the plate. During the charging phase of the heating mode, the PTC electric heater 81 heats the cooling medium and sends it into the cold plate 1. The hot medium flows along the same branched network and releases heat. At this time, the medium temperature gradually decreases along the path, with the inlet section being hot and the outlet section being cool. The gradually decreasing interstage spacing and the skeleton gradient make the heat exchange area and heat storage density of the outlet section larger, compensating for the heat exchange capacity attenuation caused by the temperature drop of the hot medium along the path. The phase change heat storage medium 1032 melts and stores heat uniformly throughout the entire plate. After melting, the heat preservation stage begins. The circulating pump 6 stops and the heating branch 8 is closed. The phase change heat storage medium 1032 slowly solidifies in the cavity. The released latent heat diffuses through the porous metal skeleton block 1031 and is then uniformly transferred to the battery 2 through the thermally conductive thin wall 15, so that the battery maintains its temperature without pump consumption or heating power consumption.

[0092] Using the above technical solution, the same group of bifurcated networks and the same group of filling cavities can reduce peaks in cooling mode and fill valleys in heating mode, allowing for bidirectional utilization of the phase change heat storage medium; the dual gradient structure compensates for the temperature rise along the medium during cooling and the temperature drop along the medium during heating, symmetrically improving the temperature uniformity of the plate surface in both modes, and this temperature uniformity is guaranteed by the internal structure of the plate, not depending on the specific form of the external valve group; during the heat preservation stage, neither the pump nor the heater works, resulting in low energy consumption at low temperatures.

[0093] In some preferred embodiments of this application, the upper threshold is 35°C and the lower threshold is 5°C, and the temperature of battery 2 is maintained at around 15°C during the heat preservation stage.

[0094] In practical implementation, the above thresholds can be calibrated according to the battery system and vehicle requirements: the suitable operating temperature range for power lithium-ion batteries is approximately 15℃ to 35℃, therefore the starting temperature for cooling mode is set at 35℃, which can be calibrated between 30℃ and 40℃; the starting temperature for heating mode is set at 5℃, which can be calibrated between 0℃ and 10℃; the target temperature of 15℃ for heat preservation is taken near the lower limit of the battery's allowable charging temperature, so that the battery can be directly charged after the heat preservation is completed. To avoid frequent operation of valves and pumps when the temperature fluctuates near the threshold, a hysteresis is set in the control, for example, the cooling cut-off temperature is about 2℃ lower than the starting temperature, and the heating cut-off temperature is about 1℃ higher than the starting temperature.

[0095] By adopting the above technical solution, the control threshold is matched with the optimal operating window of the lithium battery, and the hysteresis setting reduces the operating frequency of the commutation device 9 and the circulation pump 6, resulting in stable system operation and extended component life.

[0096] In some preferred embodiments of this application, the termination condition of the heat charging stage is that the temperature of the cooling medium or the temperature of the cold plate 1 reaches the upper limit of the phase change temperature of the phase change heat storage medium 1032 and is maintained for a set time. After the phase change heat storage medium 1032 is determined to have melted, the heat storage stage is entered. During the heat storage stage, when the temperature drops to the restart temperature between the lower limit threshold and the phase change temperature, the circulation pump 6 and the heating branch 8 are restarted to enter the heat charging stage. In the cooling mode, when the cooling branch 7 uses the air-cooled radiator 71, the speed of the fan 72 matched with the air-cooled radiator 71 increases in conjunction with the increase of the cooling medium temperature.

[0097] In practical implementation, to simplify sensor configuration, the temperature of the heat storage medium can be inferred from the temperature of the loop cooling medium or the cold plate substrate instead of measuring the temperature of the heat storage medium separately. During the charging stage, when the outlet temperature of the heating medium or the temperature of the cold plate rises above the upper limit of the phase change temperature of the heat storage medium (e.g., 40°C) and remains there for 3 to 10 minutes, it indicates that the heat storage medium in the cavity has completely melted and the heat storage is complete. The controller 12 then stops the PTC electric heater 81 and the circulating pump 6 and enters the heat preservation stage. During the heat preservation stage, the heat storage medium solidifies and releases heat, and the plate temperature slowly decreases. When the temperature drops back to the restart temperature (e.g., 10°C to 12°C), the charging stage is restarted to replenish the stored heat. In the cooling mode, the fan 72 adjusts its speed in segments according to the temperature of the cooling medium or by PID control. It runs at low speed when the temperature is low to reduce noise and at full speed when the temperature is high to ensure heat dissipation.

[0098] The above technical solution allows for the inference of phase change state using easily measurable medium temperature or plate temperature, eliminating the need for in-cavity sensors, resulting in reliable control and low cost; the restart logic ensures uninterrupted heat supply during the heat preservation stage; and the fan speed linkage achieves a balance between heat dissipation capacity and noise and energy consumption.

[0099] The synergistic arrangement of the gradually decreasing interstage spacing and the decreasing porosity of the skeleton along the flow direction simultaneously enhances the heat transfer capacity on the flow channel side and the phase change heat storage capacity on the filling cavity side along the flow direction of the cooling medium. In cooling mode, the gradually denser branched channels along the flow continuously increase the heat transfer area and improve the convective heat transfer intensity in the later section, while the gradually denser porous metal skeleton correspondingly improves the thermal conductivity and sensible heat buffering capacity of the later filling cavity. Together, they compensate for the attenuation of heat transfer temperature difference caused by the temperature rise of the cooling medium along the flow path, making the heat transfer intensity between the plate surface and the cooling medium tend to be balanced, and the temperature uniformity of the plate surface is significantly improved. In heating mode, the synergistic dual gradients in the same direction also have a compensating effect on the attenuation of heat transfer capacity caused by the temperature drop of the heating medium along the flow path, and the temperature rise of the plate surface is more uniform. The cooling and heating modes share the same circulating pump and the same cooling medium. A switching device allows for bidirectional utilization of cooling peaks and heating valleys by switching between the cooling and heating branches. The increased flow resistance caused by the denser channel design is concentrated in the later stages, which can be mitigated by matching the hydraulic dimensions of the branched channels with the operating range of the circulating pump, without affecting normal system operation. During the heat preservation phase, the circulating pump and heating branch stop working. The latent heat released by the solidification of the phase change heat storage medium is slowly released through the porous metal skeleton and thermally conductive thin walls, delaying the decrease in battery temperature without consuming pumping and heating energy.

[0100] This application achieves simultaneous enhancement of flow channel heat exchange capacity and phase change heat storage capacity along the flow direction by setting a branched channel network with 3 to 5 levels in the cold plate substrate, gradually reducing the spacing between adjacent branched channels along the flow direction, embedding closed filling cavities separated by thermally conductive thin walls in the solid area between channels, and fixing porous metal skeleton blocks and phase change heat storage medium with fixed porosity and / or filling density gradient distribution along the same direction in the cavity. Combined with parallel cooling and heating branches outside the plate, the application achieves bidirectional utilization of cooling peak shaving and heating valley filling, with good plate surface temperature uniformity, simple system structure, and low low-temperature energy consumption.

[0101] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A cold plate temperature control system for a bifurcated flow channel coupled with a heat storage medium, characterized in that, Includes a battery cold plate and an external temperature control circuit connected to the battery cold plate; The battery cold plate includes a substrate, within which a multi-level branching channel network is formed, the branching channel network having 3 to 5 levels; the branching channel network has an inlet (101) for the cooling medium to flow in and an outlet (102) for the cooling medium to flow out; along the direction of the cooling medium flowing from the inlet (101) to the outlet (102), the spacing between adjacent levels of branching channels gradually decreases; each of the substrate solid areas between two adjacent levels of branching channels of the branching channel network is provided with a closed filling cavity (14), the filling cavity (14) being not interconnected with the branching channel. Furthermore, the filling cavity (14) and the bifurcation channel are separated by a thermally conductive thin wall (15) formed of substrate body material; a porous metal skeleton block (1031) is fixed inside the filling cavity (14), and the pores of the porous metal skeleton block (1031) are filled with an organic phase change heat storage medium (1032); the porous metal skeleton block (1031) is divided into multiple segments along the flow direction of the cooling medium, and the porosity of each segment of the skeleton block decreases step by step along the flow direction of the cooling medium, so that the porosity gradient of the porous metal skeleton block corresponds to the gradual decrease in the distance between adjacent bifurcation channels along the same flow direction; The external temperature control circuit includes a main supply pipe (4), a main return pipe (5), a circulating pump (6), a cooling branch (7), a heating branch (8), a reversing device (9), a temperature sensor (11), and a controller (12). The cooling branch (7) and the heating branch (8) are connected in parallel between the main supply pipe (4) and the main return pipe (5) and are selectively connected to the external temperature control circuit via the reversing device (9). The temperature sensor (11) is used to collect temperature signals. The controller (12) controls the reversing device (9) to switch between the cooling branch (7) and the heating branch (8) according to the temperature signals.

2. The cold plate temperature control system for a bifurcated flow channel coupled with a heat storage medium according to claim 1, characterized in that, The battery cold plate includes a substrate, within which a multi-level branching channel network is formed. The branching channel network has 3 to 5 levels of branches. The branching channel network has an inlet (101) for the cooling medium to flow in and an outlet (102) for the cooling medium to flow out. Along the direction of the cooling medium flowing from the inlet (101) to the outlet (102), the spacing between adjacent levels of branching channels gradually decreases. Each adjacent branching channel of the branching channel network has a closed filling cavity (14) within the substrate body area. The filling cavity (14) is not interconnected with the branching channel. Furthermore, the filling cavity (14) and the bifurcation channel are separated by a thermally conductive thin wall (15) formed of substrate body material; a porous metal skeleton block (1031) is fixed in the filling cavity (14), and the pores of the porous metal skeleton block (1031) are filled with an organic phase change heat storage medium (1032); the porous metal skeleton block (1031) is divided into multiple segments along the flow direction of the cooling medium, and the porosity of each segment of the skeleton block decreases step by step along the flow direction of the cooling medium, so that the porosity gradient of the porous metal skeleton block corresponds to the gradual decrease in the distance between adjacent bifurcation channels along the same flow direction.

3. The cold plate temperature control system for a bifurcated flow channel coupled with a heat storage medium according to claim 2, characterized in that, Each level of the bifurcation channel is a Y-shaped two-way bifurcation channel. After each level of bifurcation, the number of channel branches is twice that before the bifurcation. The number of branches of the nth level bifurcation channel is 2 to the power of n. Adjacent level bifurcation channels are connected by a bifurcation direct current channel (110). The inlet (101) is connected to the first level bifurcation channel and the last level bifurcation channel is connected to the outlet (102) by a straight channel (104). The bifurcation channel network includes a first-level bifurcation channel (105), a second-level bifurcation channel (106), a third-level bifurcation channel (107), a fourth-level bifurcation channel (108), and a fifth-level bifurcation channel (109) connected in sequence. Along the flow direction of the cooling medium, the spacing between adjacent level bifurcation channels decreases according to an arithmetic or geometric law. When decreasing according to a geometric law, the spacing between the next level bifurcation channel and the previous level bifurcation channel is 0.6 to 0.9 times the spacing between the previous level bifurcation channel and the next level bifurcation channel.

4. The cold plate temperature control system for a bifurcated flow channel coupled with a heat storage medium according to claim 2, characterized in that, Along the flow direction of the cooling medium from the inlet (101) to the outlet (102), the porosity of the porous metal skeleton block (1031) decreases from 90% to 95% to 60% to 75%, and the filling density of the phase change heat storage medium (1032) increases in the opposite direction along the flow direction.

5. A cold plate temperature control system for a bifurcated flow channel coupled with a heat storage medium according to claim 2, characterized in that, The thickness of the thermally conductive thin wall (15) is 0.5 mm to 3 mm; the porous metal skeleton block (1031) is aluminum foam, copper foam or sintered metal porous material, and the porous metal skeleton block (1031) is fixed in the filling cavity (14) by interference fit or bonding.

6. The cold plate temperature control system for a bifurcated flow channel coupled with a heat storage medium according to claim 2, characterized in that, The organic phase change heat storage medium (1032) is a paraffin-based phase change material with a phase change temperature of 20°C to 40°C. The cavity opening of the filling cavity (14) is sealed by a cover plate (13), and the cover plate (13) is sealed to the substrate by vacuum brazing or friction stir welding. There are multiple filling cavities (14), and multiple filling cavities (14) and various levels of branch channels are arranged alternately along the surface of the substrate. Each filling cavity (14) is located in the substrate body area between adjacent branch channels and / or the direct current channel (110) between branches.

7. The cold plate temperature control system for a bifurcated flow channel coupled with a heat storage medium according to claim 1, characterized in that, The cooling branch (7) includes an air-cooled radiator (71) and a fan (72) that drives airflow through the air-cooled radiator (71), or the cooling branch (7) includes a plate heat exchanger (73) that exchanges heat with the vehicle air conditioning refrigerant circuit; the heating branch (8) includes a PTC electric heater (81), which is connected in series in the heating branch (8) and heats the cooling medium in the circuit; the reversing device (9) is any one of the following three schemes: Scheme 1, each of the cooling branch (7) and the heating branch (8) is provided with an electric two-way valve (91, 92), and the two electric two-way valves are interlocked to open and close; Scheme 2, the main supply pipe (4) or the return pipe An electric three-way valve is provided on the main liquid pipe (5), and the two branches of the electric three-way valve are respectively connected to the cooling branch (7) and the heating branch (8); in the third scheme, a four-way reversing valve is provided in the external temperature control circuit, and the four-way reversing valve connects the cooling branch (7) or the heating branch (8) to the circuit by reversing; the circulating pump (6) is a variable pump with adjustable speed, and the circuit is filled with a single cooling medium, which is ethylene glycol antifreeze, and an expansion tank (10) is connected to the common pipe section on the inlet side of the circulating pump (6); the temperature sensor (11) is attached to the surface of the battery (2) or the surface of the battery cold plate, and the controller (12) is a battery management system or an independent temperature controller.

8. The cold plate temperature control system for a bifurcated flow channel coupled with a heat storage medium according to claim 1, characterized in that, The battery cold plates are at least two and are attached to each other on opposite sides of the battery (2). The inlet (101) of each battery cold plate is connected to the main flow equalization channel (3). The main flow equalization channel (3) has a main flow equalization channel inlet (301) and a main flow equalization channel outlet (302). The outlet (102) of each battery cold plate is connected to the main flow equalization channel outlet (302). The main flow equalization channel (3) is connected in series in the external temperature control circuit.

9. A method for temperature control of a cold plate with a bifurcated flow channel coupled with a heat storage medium, characterized in that, The cold plate temperature control system using a bifurcation channel coupled heat storage medium as described in claim 1 includes the following steps: S1, collecting the temperature signal of the battery (2) or the battery cold plate through the temperature sensor (11) and transmitting the temperature signal to the controller (12); S2, when the temperature corresponding to the temperature signal is greater than or equal to the upper limit threshold, the controller (12) controls the reversing device (9) to connect the cooling branch (7) to the external temperature control circuit, the system enters the cooling mode, the circulating pump (6) drives the cooling medium to flow and absorb heat in the bifurcation channel network, the phase change heat storage medium (1032) in the filling cavity (14) absorbs the peak heat of the battery (2) and melts and stores heat, the gradually decreasing spacing of adjacent bifurcation channels along the flow direction and the porosity of the segmentally decreasing porous metal skeleton block (1031) along the same direction jointly compensate for the heat exchange temperature difference attenuation caused by the temperature rise along the cooling medium; S3, when the temperature corresponding to the temperature signal is less than or equal to the lower limit threshold. When the controller (12) controls the reversing device (9) to connect the heating branch (8) to the external temperature control circuit, the system enters the heating mode. The heating mode includes a charging stage and a heat preservation stage. In the charging stage, the heated cooling medium flows through the bifurcation channel network to release heat, causing the phase change heat storage medium (1032) to melt and store heat. The gradually decreasing spacing between adjacent bifurcation channels and the decreasing skeleton porosity along the same direction compensate for the heat exchange temperature difference attenuation caused by the temperature drop along the heating medium. In the heat preservation stage, the circulating pump (6) and the heating branch (8) stop working, the phase change heat storage medium (1032) solidifies and releases heat, and the heat is slowly released through the porous metal skeleton block (1031) and the thermally conductive thin wall (15) to heat the battery (2). S4. When the temperature corresponding to the temperature signal is between the lower threshold and the upper threshold, the circulating pump (6) stops running or runs at a small flow rate, and the system is in standby mode.

10. The method for controlling the temperature of a cold plate with a bifurcated flow channel coupled with a heat storage medium according to claim 9, characterized in that, The upper limit threshold is 35°C, the lower limit threshold is 5°C, and the temperature of the battery (2) is maintained at around 15°C during the heat preservation stage. The termination condition of the heat charging stage is that the temperature of the cooling medium or the temperature of the battery cold plate reaches the upper limit of the phase change temperature of the phase change heat storage medium (1032) and is maintained for a set time. After the phase change heat storage medium (1032) has melted, the heat preservation stage is entered. During the heat preservation stage, when the temperature drops to the restart temperature between the lower limit threshold and the phase change temperature, the circulating pump (6) and the heating branch (8) are restarted to enter the heat charging stage; in the cooling mode, when the cooling branch (7) adopts an air-cooled radiator (71), the speed of the fan (72) matched with the air-cooled radiator (71) increases in conjunction with the increase of the cooling medium temperature.

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