CN115441087A - Phase-change liquid cooling device for improving consistency of battery modules - Google Patents

Phase-change liquid cooling device for improving consistency of battery modules Download PDF

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Publication number
CN115441087A
CN115441087A CN202211077979.3A CN202211077979A CN115441087A CN 115441087 A CN115441087 A CN 115441087A CN 202211077979 A CN202211077979 A CN 202211077979A CN 115441087 A CN115441087 A CN 115441087A
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China
Prior art keywords
battery
working medium
liquid
immersed
porous
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CN202211077979.3A
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Chinese (zh)
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饶中浩
姜威
刘新健
刘臣臻
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Hebei University of Technology
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Hebei University of Technology
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Priority to CN202211077979.3A priority Critical patent/CN115441087A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/613—Cooling or keeping cold
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H01M10/0404—Machines for assembling batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H01M10/486—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte for measuring temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/617—Types of temperature control for achieving uniformity or desired distribution of temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/62—Heating or cooling; Temperature control specially adapted for specific applications
    • H01M10/625—Vehicles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/655—Solid structures for heat exchange or heat conduction
    • H01M10/6554—Rods or plates
    • H01M10/6555—Rods or plates arranged between the cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/656—Means for temperature control structurally associated with the cells characterised by the type of heat-exchange fluid
    • H01M10/6567—Liquids
    • H01M10/6568—Liquids characterised by flow circuits, e.g. loops, located externally to the cells or cell casings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/656—Means for temperature control structurally associated with the cells characterised by the type of heat-exchange fluid
    • H01M10/6569—Fluids undergoing a liquid-gas phase change or transition, e.g. evaporation or condensation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/244—Secondary casings; Racks; Suspension devices; Carrying devices; Holders characterised by their mounting method
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/249—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders specially adapted for aircraft or vehicles, e.g. cars or trains
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/289—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by spacing elements or positioning means within frames, racks or packs

Abstract

The invention discloses a phase-change liquid cooling device for improving consistency of battery modules. The invention uses the flowing boiling technology to greatly improve the heat transfer performance of the phase change liquid cooling, and the grouping efficiency is up to more than 90%. The invention adopts the gradient spacing, improves the temperature difference between groups caused by natural convection and heat accumulation effect in the traditional battery module design process, reduces the maximum temperature difference of the battery module to below 2 ℃, and has extremely high temperature consistency. The invention can overcome the temperature difference of the battery monomer caused by boundary layer effect and flow field structure in the immersion cooling design process by introducing the porous battery frame and the flow guide assembly, and further improve the temperature consistency.

Description

Phase-change liquid cooling device for improving consistency of battery modules
Technical Field
The invention relates to the field of battery temperature regulation, in particular to a phase-change liquid cooling device for improving the consistency of battery modules.
Background
With the development of economy, the quantity of automobile reserves is rapidly increased, and energy shortage and environmental pollution are brought while the economic development efficiency is accelerated. In order to relieve the situation, the new energy automobile is vigorously developed, and the important significance is achieved. The pure electric vehicle has gradually become the first choice for purchasing new energy vehicles due to the advantages of small pollution, high energy utilization efficiency, low noise, strong comfort and the like.
The safety and the service life of the lithium ion battery pack serving as a power source of the pure electric vehicle become important factors restricting the development of the industry. For safety, a number of vehicle auto-ignition events stem from battery issues. The reason is that the overall temperature of the battery is increased in the working process, a large amount of heat is generated particularly under the condition of high-rate charge and discharge, and if the heat is not conducted out in time, thermal runaway is caused, violent combustion and even explosion occur, so that the battery thermal management system of the electric automobile becomes an indispensable important component.
Existing battery thermal management means include air cooling, liquid cooling, phase change material cooling and the like, but in the face of future high-power batteries, submerged flowing boiling heat is one of the most promising thermal management technologies. Many researches show that compared with the existing heat management means, the heat conduction capacity of the flowing boiling is dozens of times of that of the traditional heat management means, and the temperature rise can be controlled below 5 ℃ under the charge-discharge multiplying power of 5℃ and is far lower than 20 ℃ of the air cooling.
The energy density of the power battery pack of the electric automobile has shown a tendency to increase by several times in recent years with respect to the service life, which also leads to a further increase in the number of internal power batteries. In the charging and discharging process of the power battery pack, due to the arrangement mode of batteries, boundary convection and heat accumulation effect, the discharging temperature of the power batteries is inevitably inconsistent, and further, the charging and discharging internal resistance, voltage and capacity of the power batteries are different. The increasing number of the single batteries of the power battery pack inevitably leads to a wooden barrel effect, namely, the single battery with the lowest capacity limits the integral energy storage capacity of the battery module. The non-uniformity of the local temperature in the discharging process of the battery pack further causes the overcharge and the overdischarge of partial battery monomers, and the butterfly effect is caused by the end of the service life of partial batteries, so that the service life of the battery pack connected with the battery pack in series is influenced.
Therefore, a cooling device for efficiently controlling the temperature and improving the consistency of the battery module is developed for future high-energy-density battery packs, and is very important for prolonging the service life and ensuring the use safety.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a phase-change liquid cooling device for improving the consistency of a battery module.
The invention provides a phase-change liquid cooling device for improving the consistency of battery modules, which is characterized by comprising a porous battery frame, a temperature sensor, a flow guide assembly, an electromagnetic one-way valve, an immersed liquid-cooled battery cabin and a pressure sensor, wherein the porous battery frame is arranged on the outer side of the battery frame;
the bottom in the immersed liquid-cooled battery compartment is provided with a plurality of battery tanks, and each battery tank is internally provided with a power battery; along the arrangement direction of the battery tanks, the distance between two adjacent battery tanks is increased in gradient from the side wall of the immersed liquid-cooled battery compartment to the central position, the distance between the inner side of the side wall of the immersed liquid-cooled battery compartment and the two battery tanks on the outermost side is the smallest, and the distance between the two battery tanks on the central position is the largest;
a porous battery rack is arranged at each battery jar; the porous battery rack is fixed on the bottom in the immersed liquid-cooled battery cabin; the porous battery frames are closely contacted with the respective power batteries and support the power batteries; two ends of the plurality of flow guide assemblies are respectively fixed between two adjacent porous battery racks or between the inner side of the side wall of the immersed liquid-cooled battery cabin and the two outermost porous battery racks and are used for guiding the flow of low-boiling-point working media; each power battery is provided with a temperature sensor for measuring the temperature of each power battery; the immersed liquid-cooled battery cabin is provided with a working medium inlet and a working medium outlet; an electromagnetic one-way valve and a pressure sensor are arranged at the working medium outlet, and the pressure sensor is used for measuring the internal pressure of the immersed liquid-cooled battery compartment and regulating the internal pressure of the immersed liquid-cooled battery compartment by opening and closing the electromagnetic one-way valve;
the flow guide assembly consists of three flow guide plates; the three guide plates are arranged along the vertical direction, and two side walls of the three guide plates are respectively fixed between two adjacent porous battery racks or between the inner side of the side wall of the immersed liquid-cooled battery cabin and the two outermost porous battery racks; the arrangement of the three guide plates obeys logarithmic distribution or Fibonacci spiral distribution.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention greatly improves the heat transfer performance of the phase change liquid cooling by using the flowing boiling technology, and compared with the traditional temperature control mode, the temperature control requirement of high charge-discharge multiplying power of the racetrack can be met by testing. And can use less working medium to carry out the temperature control of the whole working condition to the electric automobile, and then realize that the uniting efficiency reaches more than 90%.
(2) The invention adopts gradient spacing, and improves the temperature difference between groups caused by natural convection and heat accumulation effect in the traditional battery module design process. Theoretical analysis and experiments prove that the boiling state among all power batteries can be regulated and controlled by introducing the gradient intervals, so that the heat taken away by the power batteries through flowing boiling is equivalent to the heat taken away by combining the flowing boiling through heat conduction, the temperature difference among the batteries is remarkably reduced, the maximum temperature difference of the battery modules is reduced to be below 2 ℃, and the temperature consistency is extremely high. The gradient spacing designed by the invention is suitable for any connection mode of series connection, parallel connection or series-parallel connection of the power batteries.
(3) The invention can overcome the temperature difference of the battery monomer caused by boundary layer effect and flow field structure of the working medium in the immersion cooling design process by introducing the porous battery frame and the flow guide assembly. Theoretical analysis and experiments prove that the distribution of the immersed liquid cooling flow field can be improved by the guide assemblies distributed in the logarithmic curve and the Fibonacci spiral line, and sufficient nucleation sites are added while the contact thermal resistance is reduced by matching with the porous battery frame, so that the boiling heat exchange of the low-boiling-point working medium is enhanced, and the temperature consistency is further improved.
(4) The integral design of the immersed liquid-cooled battery compartment enables all parts in the compartment to be in close contact and mutually supported, thereby enhancing the structural rigidity and stability and reducing the contact thermal resistance.
(5) The electromagnetic one-way valve and the pressure sensor are matched with each other, pressure distribution in the bin can be reasonably adjusted, self-driving of the working medium is achieved by utilizing pressure difference in the phase change process, and energy consumption caused by intervention of the pump is reduced.
(6) The liquid cooling method can realize the autonomous circulation of the low-boiling point working medium in the system under the working conditions of low-speed and low-power discharge through the pressure difference generated by the gas-liquid phase change of the low-boiling point working medium, and does not need a circulating pump to provide power. Under the working condition of high-speed and high-power discharge, the circulating pump is used for providing power in an auxiliary mode, and the energy-saving effect is achieved.
Drawings
FIG. 1 is a schematic front view of the overall structure of an embodiment of the present invention;
FIG. 2 is a schematic front view of the overall structure of another embodiment of the present invention;
FIG. 3 is a perspective view of an immersed liquid-cooled battery compartment of the present invention;
FIG. 4 is an installation view of the power cell, porous cell holder and flow directing assembly of the present invention;
FIG. 5 is a flow chart of a phase change liquid cooling method of a power battery according to the present invention;
FIG. 6 is a block diagram of a thermal management system of the present invention;
FIG. 7 is a graph showing the maximum temperature difference of 12 power cells with different gradient pitches according to example 1 of the present invention as a function of the test time;
FIG. 8 is a graph of temperature distribution of 12 power cells with different gradient spacing according to example 1 of the present invention at test times of 40s and 116 s;
fig. 9 is a graph of the average temperature rise of 12 power cells at different pack efficiencies according to example 1 of the present invention as a function of test time;
fig. 10 is a graph of the maximum temperature difference of 12 power cells at different pack efficiencies according to example 1 of the present invention as a function of test time.
In the figure, a power battery 101, a porous battery frame 102, a temperature sensor 103, a flow guide assembly 104, an electromagnetic one-way valve 105, a battery jar 106, an immersed liquid-cooled battery compartment 107, a tab 108, a tab connecting sheet 109, a working medium inlet 110, a working medium outlet 111, a circulating pump 112, a liquid storage tank 113, a one-way valve 114, a pressure sensor 115 and a condenser 116.
Detailed Description
Specific examples of the present invention are given below. The specific examples are only for illustrating the present invention in further detail and do not limit the scope of the claims of the present invention.
The invention provides a phase-change liquid cooling device (liquid cooling device for short) for improving consistency of battery modules, which is characterized by comprising a porous battery frame 102, a temperature sensor 103, a flow guide assembly 104, an electromagnetic one-way valve 105, an immersed liquid cooling battery chamber 107 and a pressure sensor 115;
the bottom in the immersed liquid-cooled battery chamber 107 is provided with a plurality of (preferably, at least three) battery tanks 106, the battery tanks 106 are used for placing the power batteries 101, and each battery tank 106 is internally provided with one power battery 101; the battery jar 106 is a main temperature equalizing component for improving the heat accumulation of the battery module and the natural convection temperature difference of the shell; along the arrangement direction of the battery jars 106, from the side wall of the immersed liquid-cooled battery compartment 107 to the center position, the distance between two adjacent battery jars 106 is increased in gradient, the distance between the inner side of the side wall of the immersed liquid-cooled battery compartment 107 and two outermost battery jars 106 (namely, the first battery jar 106 or the last battery jar 106) is the smallest, and the distance between two battery jars 106 at the center position is the largest;
a porous battery holder 102 is arranged at each battery jar 106; the porous battery holder 102 is fixed on the bottom inside the immersed liquid-cooled battery compartment 107, and the inner wall of the porous battery holder is flush with the wall of the battery jar 106; each porous battery frame 102 is internally provided with a power battery 101 which is tightly contacted with the respective power battery 101 and supports the power battery 101; two ends of the plurality of flow guide assemblies 104 are respectively fixed between two adjacent porous battery racks 102 or between the inner side of the side wall of the immersed liquid-cooled battery compartment 107 and two outermost porous battery racks 102 (namely, the first porous battery rack 102 or the last porous battery rack 102) for guiding the flow of the low-boiling-point working medium; each power battery 101 is provided with a temperature sensor 103 for measuring the temperature of each power battery 101; the immersed liquid-cooled battery compartment 107 is provided with a working medium inlet 110 and a working medium outlet 111; an electromagnetic check valve 105 and a pressure sensor 115 are arranged at the working medium outlet 111, and the pressure sensor 115 is used for measuring the internal pressure of the immersed liquid cooling battery compartment 107 and regulating and controlling the internal pressure of the immersed liquid cooling battery compartment 107 by opening and closing the electromagnetic check valve 105.
Preferably, the battery slots 106 at the same positions on the left and right sides are equally spaced with the center position as the axis of symmetry.
Preferably, the pitch is calculated by the formula f (x) = kx + b, where f (x) is the pitch value of the x-th pitch, k is the gradient, and k is 6% to 45%, and b = (the length of the immersed liquid-cooled battery compartment 107 in the arrangement direction of the battery slots 106-the number of the power batteries 101 ×. The thickness of the power batteries 101)/2), so that the pitch gradually increases from the minimum pitch to the maximum pitch with a gradient of 6% to 45%, and the pitches are distributed in an arithmetic progression. In this embodiment, the minimum distance is 1-6 mm, which can meet the temperature control requirement of high load discharge.
Preferably, if the number of the battery slots 106 is n, the number of the diversion assemblies 104 is n +1; when n is an odd number, the two battery slots 106 at the center position are the (n-1/2) th battery slot and the (n + 1/2) th battery slot, or the (n + 1/2) th battery slot and the (n + 3/2) th battery slot; when n is an even number, the two battery slots 106 at the center position are the n/2 th battery slot and the n +2/2 th battery slot.
Preferably, the porous battery frame 102 is used as a main component for fixing the power battery 101 and a main nucleation site, and has a strong pre-tightening force; the porous structure increases boiling nucleation sites and enhances boiling heat transfer; the material is a foam metal with high thermal conductivity, has higher structural strength and PPI (pore density) higher than 2000; the wall thickness is less than 0.5mm.
Preferably, the flow guide assembly 104 is a main component for improving the temperature difference of the single body of the power battery 101 and is composed of three flow guide plates; three guide plates are arranged along the vertical direction, and two side walls of the three guide plates are respectively fixed between two adjacent porous battery racks 102 or between the inner side of the side wall of the immersed liquid-cooled battery bin 107 and the two outermost porous battery racks 102; the arrangement of the three guide plates obeys logarithmic distribution or Fibonacci spiral distribution;
when three guide plates are arranged and obey logarithmic distribution, taking the vertical wall surface of the immersed liquid-cooled battery compartment 107 provided with the working medium inlet 110 as an x axis, taking the upper surface of the bottom surface of the immersed liquid-cooled battery compartment 107 as a y axis, making a logarithmic curve with the bottom number of a, respectively taking coordinate points corresponding to x =1/3a, 2/3a and a on the logarithmic curve, then installing one guide plate according to a line segment formed by the coordinate point corresponding to x =1/3a and the midpoint of the vertical side of the side surface of the porous battery frame 102, installing one guide plate according to a line segment formed by the coordinate point corresponding to x =2/3a and the diagonal point of the side surface of the porous battery frame 102, and installing one guide plate according to a line segment formed by the coordinate point corresponding to x = a and the midpoint of the top edge of the side surface of the porous battery frame 102;
when three guide plates are arranged to obey Fibonacci spiral distribution, a vertical wall surface of the immersed liquid-cooled battery compartment 107 with the working medium inlet 110 is taken as an x axis, an upper surface of the bottom surface of the immersed liquid-cooled battery compartment 107 is taken as a y axis, fibonacci spiral lines are formed, coordinate points corresponding to three points x = F3.5, F3 and F2.5 are respectively taken on the Fibonacci spiral lines, then one guide plate is arranged according to a line segment formed by the coordinate point corresponding to x = F3.5 and a midpoint of a vertical edge of the side surface of the porous battery holder 102, one guide plate is arranged according to a line segment formed by the coordinate point corresponding to x = F3 and a diagonal point of the side surface of the porous battery holder 102, and one guide plate is arranged according to a line segment formed by the coordinate point corresponding to x = F2.5 and a midpoint of a top edge of the side surface of the porous battery holder 102.
Preferably, the working fluid outlet 111 is a tapered outlet such that the flow field around each power cell 101 in the submerged liquid-cooled battery compartment 107 tends to be uniform.
Preferably, the main body of the immersion liquid-cooled battery compartment 107 is made of aluminum alloy, and is divided into a top cover and a compartment body. During assembly and maintenance, the top cover is opened, the power battery 101 is inserted into the porous battery frame 102 with pretightening force, and the power battery and the porous battery frame are in close contact; after the assembly and the overhaul are finished, the top cover and the bin body are fixed through a corrosion-resistant fluororubber sealing ring and a bolt.
Preferably, the walls of the battery well 106 are coated with an insulating coating to insulate the interface of the power battery 101 and the submerged liquid-cooled battery compartment 107.
Preferably, the working medium with low boiling point adopts an insulating, high-stability and flashpoint-free working medium, preferably R141b (monofluorodichloroethane).
Preferably, the tab 108 and the tab connecting sheet 109 of the power battery 101 are opposite to the working medium inlet 110 of the immersed liquid cooling battery compartment 107, so that the tab 108 which generates high heat and various parts connected with the tab are cooled, and the internal temperature difference of the single battery is reduced.
Preferably, the solenoid check valve 105 is mounted at the working medium outlet 111 by a fluoro-rubber seal ring and a self-snap collar.
The invention also provides an immersed flow boiling heat management system (referred to as heat management system for short) of the device, which is characterized by comprising a circulating pump 112, a liquid storage tank 113, a one-way valve 114, a controller and a condenser 116;
liquid working medium with low boiling point is stored in the liquid storage tank 113; a working medium inlet 110 of the immersed liquid cooling battery compartment 107 is communicated with an outlet of a liquid storage tank 113 through a pipeline, and a one-way valve 114 is arranged on the pipeline; the one-way valve 114 realizes that the working medium with low boiling point can only flow to the immersed liquid cooling battery compartment 107 from the liquid storage tank 113, but can not flow to the liquid storage tank 113 from the immersed liquid cooling battery compartment 107; the working medium outlet 111 of the immersed liquid cooling battery chamber 107 is communicated with the inlet of the condenser 116 through a pipeline; the condenser 116 is used for condensing the gasified low-boiling point working medium steam into liquid; the outlet of the condenser 116 is communicated with the inlet of the liquid storage tank 113 through a pipeline; a circulating pump 112 is arranged in the whole circulating pipeline and used as a power source for flowing of a low-boiling-point working medium (in the embodiment, an outlet of the condenser 116 is communicated with an inlet of the liquid storage tank 113 through a pipeline, and the circulating pump 112 is arranged on the pipeline);
the controller is respectively connected with the circulating pump 112, the temperature sensor 103, the electromagnetic one-way valve 105 and the pressure sensor 115 in a communication way.
The invention also provides a phase-change liquid cooling method (short method) of the power battery based on the thermal management system, which is characterized by comprising the following steps:
the battery module is started, and when the controller monitors that the temperature measured by all the temperature sensors 103 is less than 40 ℃, the low-boiling-point working medium enters a self-driving mode; in the self-driving mode, the controller controls the circulation pump 112 and the electromagnetic one-way valve 105 to be closed, and the immersed liquid-cooled battery compartment 107 is in a closed state; the low boiling point working medium in the immersed liquid cooling battery compartment 107 rapidly absorbs heat and undergoes gas-liquid phase change under the action of the porous battery frame 102, the internal pressure of the immersed liquid cooling battery compartment 107 is continuously increased due to the continuous increase of the gas phase until the pressure detected by the pressure sensor 115 reaches the pressure difference required for overcoming the on-way resistance, the controller controls the electromagnetic one-way valve 105 to be opened, the low boiling point working medium in a gas-liquid two-phase coexistence state flows out from the working medium outlet 111 under the driving of the pressure difference, flows through the condenser 116 to become a liquid phase, the liquid low boiling point working medium flows through the liquid storage tank 113 and pushes the liquid low boiling point working medium in the liquid storage tank 113 to flow, enters the immersed liquid cooling battery compartment 107 from the working medium inlet 110 through the one-way valve 114, then flow is redistributed under the action of the battery tank 106 with gradient spacing, the flow is guided through the flow guide assembly 104 until the power battery 101 is immersed in the low boiling point working medium, the heat generated by the power battery 101 is taken away under the action of intensified boiling of the porous battery frame 102, and the electromagnetic cooling battery compartment 107 is closed until the internal pressure is in a stable state, and the electromagnetic cooling one-way valve 105 is closed, and the electromagnetic cooling cycle is completed;
when the controller monitors that the highest value of the temperature measured by all the temperature sensors 103 is more than 40 ℃, the working medium with the low boiling point enters a forced convection mode; in the forced convection mode, the controller controls the circulation pump 112 and the electromagnetic one-way valve 105 to be opened, and the low-boiling-point working medium flows out of the liquid storage tank 113 under the driving of the circulation pump 112 and enters the immersed liquid-cooled battery compartment 107 from the working medium inlet 110 through the one-way valve 114; then, after the flow is redistributed under the action of a battery jar 106 with gradient spacing, the flow is guided by a guide assembly 104 until the power battery 101 is immersed in a working medium with a low boiling point, the heat generated by the power battery 101 is taken away under the action of enhanced boiling heat exchange of a porous battery frame 102, and then the heat flows out of a working medium outlet 111 to complete a cooling cycle; in the forced convection mode, when the controller monitors that the temperature measured by all the temperature sensors 103 is reduced to 20-30 ℃, the controller controls the circulation pump 112 and the electromagnetic one-way valve 105 to be closed, and the low-boiling-point working medium enters the self-driving mode.
Example 1
As shown in fig. 1, in the present embodiment, n =12 power cells 101 are used, and the tab 108 and the tab connecting piece 109 of each power cell 101 are upward (i.e., on the top); the length of the immersed liquid-cooled battery compartment 107 is 400mm, and the thickness of the power battery 101 is 27mm; in this embodiment, the gradually increasing pitches of the gradients of k =0%, 6%, 45%, 81%, and 110% are adopted, for example, the minimum pitch corresponding to the 6% gradient is f (1) =0.06 × 1+5.62=5.68mm. In the embodiment, the low-boiling point working medium adopts R141b, the saturation temperature is 32.1 ℃ under normal pressure, the inlet working medium is in a supercooled state, and the flow speed is 0.01m/s. The flow rate used by the invention is relatively appropriate flow rate applied to the temperature control of the heat flow of the battery.
As can be seen from fig. 7, in the case of different gradient pitches, the temperature difference of each cell undergoes a state of increasing and then decreasing and then gradually approaches to a stable state, and the corresponding flow state gradually transits from supercooling convection to flow boiling.
As can be seen from fig. 8, the inter-group cell temperature distribution in the convection and boiling regions without using the gradient pitch shows a state in which the middle cell temperature is higher than the two sides, but as the pitch gradient gradually increases, the temperature distribution in both the convection region and the boiling region gradually becomes uniform and then changes to a state in which the middle cell temperature is lower than the two sides. Therefore, the battery module has better temperature consistency by taking the k as the distance gradient in the range of 6-45%.
This example tested 73%, 80%, 84%, 98%, and 95% battery efficiency, respectively, as the change in the heat transfer characteristics of the battery module over time, with the battery efficiency calculation formula being the volume of the submerged liquid-cooled battery compartment 107 divided by the volume of the power cells 101.
As can be seen in fig. 9, the internal cell temperature rise in the liquid cooling device transitioning from subcooled convection to boiling conditions remains substantially uniform as the packing efficiency is gradually increased.
As can be seen from FIG. 10, as the packing efficiency increases, the working fluid more easily reaches the boiling state, and the maximum temperature difference between the packs is maintained within 0.8K. Therefore, the gradient spacing and the grouping efficiency of the liquid cooling device can effectively improve the consistency of the battery modules.
The characteristics are tested by taking the track discharge data of the high-performance electric racing car as a reference, and the temperature control performance and the battery consistency can ensure the use requirements of the household electric car.
Example 2
As shown in fig. 2, in this embodiment, the tab 108 and the tab connecting sheet 109 of the power battery 101 are directly opposite to the working medium inlet 110 of the immersion type liquid cooling battery compartment 107, so that the tab 108 which generates high heat and each part connected with the tab are cooled, and the internal temperature difference of the single battery is reduced.
The invention is applicable to the prior art where nothing is said.

Claims (10)

1. A phase-change liquid cooling device for improving consistency of battery modules is characterized by comprising a porous battery frame (102), a temperature sensor (103), a flow guide assembly (104), an electromagnetic one-way valve (105), an immersed liquid-cooled battery chamber (107) and a pressure sensor (115);
a plurality of battery tanks (106) are arranged at the bottom in the immersed liquid-cooled battery cabin (107), and a power battery (101) is placed in each battery tank (106); along the arrangement direction of the battery tanks (106), the gradient of the distance between two adjacent battery tanks (106) is increased from the side wall of the immersed liquid-cooled battery bin (107) to the center position, the distance between the inner side of the side wall of the immersed liquid-cooled battery bin (107) and the two battery tanks (106) at the outermost side is minimum, and the distance between the two battery tanks (106) at the center position is maximum;
a porous battery rack (102) is arranged at each battery groove (106); the porous battery rack (102) is fixed on the bottom in the immersed liquid-cooled battery cabin (107); the porous battery frames (102) are closely contacted with the respective power batteries (101) and support the power batteries (101); two ends of the plurality of flow guide assemblies (104) are respectively fixed between two adjacent porous battery frames (102) or between the inner side of the side wall of the immersed liquid-cooled battery bin (107) and the two outermost porous battery frames (102) and are used for guiding the flow of low-boiling-point working media; each power battery (101) is provided with a temperature sensor (103) for measuring the temperature of each power battery (101); the immersed liquid cooling battery compartment (107) is provided with a working medium inlet (110) and a working medium outlet (111); an electromagnetic one-way valve (105) and a pressure sensor (115) are arranged at the working medium outlet (111), the pressure sensor (115) is used for measuring the internal pressure of the immersed liquid-cooled battery compartment (107) and regulating and controlling the internal pressure of the immersed liquid-cooled battery compartment (107) by opening and closing the electromagnetic one-way valve (105);
the flow guide assembly (104) consists of three flow guide plates; the three guide plates are arranged along the vertical direction, and two side walls of the three guide plates are respectively fixed between two adjacent porous battery racks (102) or between the inner side of the side wall of the immersed liquid-cooled battery cabin (107) and the two outermost porous battery racks (102); the arrangement of the three guide plates obeys logarithmic distribution or Fibonacci spiral distribution.
2. The phase-change liquid cooling device for improving the uniformity of battery modules according to claim 1, wherein the battery grooves (106) at the same positions on the left and right sides have the same pitch with the central position as a symmetry axis.
3. A phase-change liquid cooling device for improving consistency of battery modules according to claim 1, wherein the spacing is calculated by a formula f (x) = kx + b, wherein f (x) is a spacing value of the x-th spacing, k is a gradient, k is 6% to 45%, and b = (length of the immersed liquid-cooled battery compartment-number of power batteries × (thickness of power batteries)/2.
4. The phase-change liquid cooling device for improving the consistency of battery modules according to claim 1, wherein the number of the battery grooves (106) is n, and the number of the flow guide assemblies (104) is n +1; when n is an odd number, the two battery slots (106) at the central position are the (n-1/2) th battery slot and the (n + 1/2) th battery slot, or the (n + 1/2) th battery slot and the (n + 3/2) th battery slot; when n is an even number, the two battery slots (106) at the center position are the n/2 th battery slot and the n +2/2 th battery slot.
5. The phase-change liquid cooling device for improving the consistency of the battery modules according to claim 1, wherein the material of the porous battery frame (102) is high-thermal-conductivity foam metal, and the PPI is higher than 2000; the wall thickness of the porous battery frame (102) is less than 0.5mm; the walls of the battery well (106) are coated with an insulating coating.
6. The phase-change liquid cooling device for improving the consistency of the battery module according to claim 1, wherein when three flow deflectors are arranged according to a logarithmic distribution, a logarithmic curve with the base number a is drawn by taking the vertical wall surface of the immersed liquid-cooled battery compartment (107) provided with the working medium inlet (110) as an x axis and the upper surface of the bottom surface of the immersed liquid-cooled battery compartment (107) as a y axis, coordinate points corresponding to three points x =1/3a, 2/3a and a are respectively taken on the logarithmic curve, one flow deflector is arranged according to a line segment formed by the coordinate point corresponding to x =1/3a and the midpoint of the vertical side of the side surface of the porous battery holder (102), one flow deflector is arranged according to a line segment formed by the coordinate point corresponding to x =2/3a and the diagonal point of the side surface of the porous battery holder (102), and one flow deflector is arranged according to a line segment formed by the coordinate point corresponding to x = a and the midpoint of the top side surface of the porous battery holder (102).
7. The phase-change liquid cooling apparatus for improving the uniformity of a battery module according to claim 1, wherein when three guide plates are arranged so as to follow a fibonacci spiral distribution, coordinate points corresponding to three points x = F3.5, F3 and F2.5 are respectively taken on the fibonacci spiral with the vertical wall surface of the immersed liquid-cooled battery case (107) where the working medium inlet (110) is opened as an x-axis and the upper surface of the bottom surface of the immersed liquid-cooled battery case (107) as a y-axis, and one guide plate is arranged along a line segment formed by the coordinate point corresponding to x = F3.5 and the midpoint of the vertical side of the porous battery holder (102), one guide plate is arranged along a line segment formed by the coordinate point corresponding to x = F3 and the diagonal point of the side of the porous battery holder (102), and one guide plate is arranged along a line segment formed by the coordinate point corresponding to x = F2.5 and the midpoint of the top side of the porous battery holder (102).
8. The phase-change liquid cooling device for improving consistency of battery modules according to claim 1, wherein the working medium outlet (111) is a tapered outlet, so that a flow field around each power battery (101) in the immersed liquid-cooled battery compartment (107) tends to be consistent.
9. An immersed flow boiling heat management system as in any of the devices of claims 1 to 8, wherein the heat management system comprises a circulation pump (112), a tank (113), a one-way valve (114), a controller and a condenser (116);
liquid working medium with low boiling point is stored in the liquid storage tank (113); a working medium inlet (110) of the immersed liquid cooling battery compartment (107) is communicated with an outlet of the liquid storage tank (113) through a pipeline, and a one-way valve (114) is arranged on the pipeline; the one-way valve (114) realizes that the working medium with low boiling point can only flow to the immersed liquid cooling battery compartment (107) from the liquid storage tank (113); a working medium outlet (111) of the immersed liquid cooling battery compartment (107) is communicated with an inlet of the condenser (116) through a pipeline; the condenser (116) is used for condensing the gasified low-boiling point working medium steam into liquid; an outlet of the condenser (116) is communicated with an inlet of the liquid storage tank (113) through a pipeline; a circulating pump (112) is arranged in the whole circulating pipeline;
the controller is respectively connected with the circulating pump (112), the temperature sensor (103), the electromagnetic one-way valve (105) and the pressure sensor (115) in a communication mode.
10. The phase-change liquid cooling method for the power battery based on the heat management system of claim 9 is characterized by comprising the following steps:
when the controller monitors that the temperature measured by all the temperature sensors (103) is less than 40 ℃, the low-boiling point working medium enters a self-driving mode; in a self-driving mode, the controller controls the circulating pump (112) and the electromagnetic one-way valve (105) to be closed, and the immersed liquid-cooling battery compartment (107) is in a closed state; the method comprises the steps that a low-boiling-point working medium in an immersed liquid cooling battery compartment (107) rapidly absorbs heat and generates gas-liquid phase change under the action of a porous battery frame (102), the internal pressure of the immersed liquid cooling battery compartment (107) is continuously increased due to continuous increase of a gas phase until a pressure detected by a pressure sensor (115) is detected by a controller to reach a pressure difference required for overcoming on-way resistance, the controller controls an electromagnetic one-way valve (105) to be opened, the low-boiling-point working medium in a gas-liquid two-phase coexistence state flows out from a working medium outlet (111) under the driving of the pressure difference and is changed into a liquid phase through a condenser (116), the liquid low-boiling-point working medium flows through a liquid storage tank (113) and pushes the liquid low-boiling-point working medium in the liquid storage tank (113) to flow, the liquid low-boiling-point working medium enters the immersed liquid cooling battery compartment (107) from a working medium inlet (110) through a one-way valve (114), then flow is redistributed under the action of a battery tank (106), the flow is guided through a flow guide assembly (104) until the immersed power battery (101) is immersed in the low-boiling-point working medium, the heat of the immersed battery compartment (105) is stably carried away under the action of the porous battery frame (102), and the one-liquid cooling battery compartment, and the internal pressure of the immersed battery compartment is controlled to be closed, and the electromagnetic one-liquid cooling battery compartment (105);
when the controller monitors that the highest value of the temperature measured by all the temperature sensors (103) is more than 40 ℃, the low-boiling point working medium enters a forced convection mode; in a forced convection mode, the controller controls the circulation pump (112) and the electromagnetic one-way valve (105) to be opened, and the low-boiling-point working medium flows out of the liquid storage tank (113) under the driving of the circulation pump (112) and enters the immersed liquid-cooled battery compartment (107) from the working medium inlet (110) through the one-way valve (114); then, after the flow is redistributed under the action of a battery tank (106), the flow is guided by a guide component (104) until the power battery (101) is immersed in a working medium with a low boiling point, the heat generated by the power battery (101) is taken away under the action of enhanced boiling heat exchange of a porous battery rack (102), and then the heat flows out of a working medium outlet (111) to complete a cooling cycle; in the forced convection mode, when the controller monitors that the temperature measured by all the temperature sensors (103) is reduced to 20-30 ℃, the controller controls the circulation pump (112) and the electromagnetic one-way valve (105) to be closed, and the low-boiling-point working medium enters the self-driving mode.
CN202211077979.3A 2022-09-05 2022-09-05 Phase-change liquid cooling device for improving consistency of battery modules Pending CN115441087A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117673567A (en) * 2024-01-30 2024-03-08 东南大学 Immersion liquid cooled battery stack and apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117673567A (en) * 2024-01-30 2024-03-08 东南大学 Immersion liquid cooled battery stack and apparatus
CN117673567B (en) * 2024-01-30 2024-04-05 东南大学 Immersion liquid cooled battery stack and apparatus

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