Immersed liquid cooling battery cooling device and energy storage battery pack

Abstract

The utility model provides an immersed liquid cooling battery cooling device and an energy storage battery pack, and belongs to the field of battery liquid cooling, the top of a shell is provided with an exhaust port, and the exhaust port exhausts air above the liquid level of the shell; the cooling pipe is arranged in the shell and located at the top of the battery, and the cooling pipe is immersed below the liquid level of the heat-conducting medium; the air delivery pipe is arranged in the shell and located at the bottom of the battery, and air holes are distributed in the air delivery pipe; clean air is stored in the air storage tank; the bubble generating device is communicated between the air storage tank and the air conveying pipe and conveys high-pressure air flow to the heat conduction medium from bottom to top through the air holes. According to the utility model, high-pressure gas is sprayed from the bottom of the battery from bottom to top through the gas delivery pipe, and bubble flow is formed in gaps of the battery, so that immersion cooling liquid in a flow channel is greatly disturbed, and a thermal boundary layer formed on the surface of a battery pack due to low-speed flowing of the immersion cooling liquid is further damaged; and the convective heat transfer coefficient of the immersion liquid on the surface of the battery pack can be greatly improved, and the cooling capacity of the immersion liquid on the battery side is improved.

Description

Technical Field

[0001] This utility model relates to the field of battery liquid cooling technology, and in particular to an immersion liquid cooling battery cooling device and energy storage battery pack. Background Technology

[0002] In recent years, with the rapid development of electrochemical energy storage technology, immersion liquid-cooled energy storage systems have gradually become the mainstream design solution for large-capacity battery packs due to their efficient heat dissipation capabilities and intrinsic safety. For example, Tesla's patent US20210083221A1 uses the density difference of the immersion liquid caused by battery heating to form a thermal cycle of convection between the upper and lower parts of the immersion liquid. Specifically, the immersion liquid becomes less dense when heated, so the high-temperature immersion liquid rises and comes into contact with the liquid cooling plate set at the top of the immersion liquid. After heat exchange between the high-temperature immersion liquid and the liquid cooling plate, the liquid cools down and falls back to the bottom.

[0003] The current method of cooling batteries by immersion in coolant and natural convection has limited cooling effect. This is because, when the immersion liquid flows over the battery surface, the flow rate is relatively slow, which forms a thick thermal boundary layer on the battery surface. This thermal boundary layer hinders the heat transfer effect of natural convection. Utility Model Content

[0004] In view of this, this utility model proposes an immersion liquid-cooled battery cooling device and energy storage battery pack to solve the problem that the current method of cooling batteries by natural convection cooling with immersion coolant has a very poor cooling effect.

[0005] The technical solution of this utility model is implemented as follows: This utility model provides an immersion liquid-cooled battery cooling device, including a shell, a cooling pipe, a gas supply pipe, a bubble generator, and a gas storage tank; a plurality of batteries are arranged inside the shell, the shell is filled with a heat-conducting medium and the batteries are immersed, and an exhaust port is provided at the top of the shell to discharge air above the liquid surface of the shell; the cooling pipe is arranged inside the shell and located at the top of the batteries, and the cooling pipe is immersed below the liquid surface of the heat-conducting medium; the gas supply pipe is arranged inside the shell and located at the bottom of the batteries, and the gas supply pipe is provided with air holes; clean air is stored in the gas storage tank; the bubble generator is connected between the gas storage tank and the gas supply pipe, and the bubble generator delivers high-pressure airflow to the heat-conducting medium from bottom to top through the air holes.

[0006] Based on the above technical solutions, preferably, it also includes a gas-liquid separation device; a reflux port is opened on the side wall of the shell near the liquid surface of the heat transfer medium; the gas-liquid separation device is connected between the gas storage tank and the exhaust port, and the gas-liquid separation device is also connected to the reflux port. The gas-liquid separation device collects the air discharged from the exhaust port, and after separating the air into gas and liquid phases, the gas-liquid separation device transports the liquid phase back into the shell through the reflux port and transports the gas phase to the gas storage tank.

[0007] In a further preferred embodiment, gaps are left between the dry cell batteries, and several air holes arranged on each air supply pipe are arranged in a row, or several corresponding air holes on each air supply pipe are arranged in a row, with each row of air holes aligned with the gaps.

[0008] Even more preferably, the temperature difference between the battery surface and the heat-conducting medium is adjusted by adjusting the width of the gap.

[0009] Furthermore, the formula for calculating the gap width is:

[0010] S=CL×(gβ△TL 3 / αv) 0.25 ,

[0011] Where C is an empirical constant, L is the height of the battery, g is the gravitational acceleration, β is the thermal expansion coefficient of the heat-conducting medium, ΔT is the temperature difference between the battery surface and the heat-conducting medium, α is the thermal diffusivity of the heat-conducting medium, and v is the viscosity of the immersion coolant.

[0012] Even more preferably, the width of the gap is no more than 10cm.

[0013] More preferably, the gas transmission pipe includes branch pipes and a main pipe, with several branch pipes arranged one-to-one in each gap, and several air holes arranged on the branch pipes; the main pipe is connected to one end of several branch pipes at the same time, one end of the main pipe extends through the shell to the external environment, and the outer end of the main pipe is connected to the gas storage tank through a bubble generating device.

[0014] Based on the above technical solutions, preferably, the pore diameter is 1-2 cm and the spacing between adjacent pores is 3-5 cm.

[0015] Based on the above technical solutions, preferably, the solution also includes a liquid storage tank and a delivery pump; the liquid storage tank is connected to the output and input ends of the cooling pipe, and the liquid storage tank stores cooling water; the delivery pump is connected between the liquid storage tank and the input end of the cooling pipe, and the delivery pump pumps cooling water to the heat exchange pipe.

[0016] On the other hand, this utility model also provides an energy storage battery pack that uses the above-mentioned immersion liquid cooling battery cooling device.

[0017] The immersion liquid-cooled battery cooling device and energy storage battery pack of this utility model have the following advantages over the prior art:

[0018] (1) This utility model sprays high-pressure gas from the bottom of the battery upward through the gas delivery pipe, forming a bubble flow in the gap between the batteries. This will cause a large disturbance to the immersion coolant in the flow channel, thereby destroying the thermal boundary layer formed on the surface of the battery pack due to the low-speed flow of the immersion coolant. This can greatly improve the convective heat transfer coefficient of the immersion coolant on the surface of the battery pack and improve the heat dissipation capacity of the immersion coolant on the battery side.

[0019] (2) Based on the resistance of the flow of high-viscosity oily fluid, this utility model adjusts the optimal gap distance of the battery, thereby effectively destroying the thermal boundary layer formed on the surface of the battery pack due to the low-speed flow of the submerged coolant by the high-pressure airflow. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a perspective view of the immersion-type battery liquid cooling device of this utility model;

[0022] Figure 2 This is a side sectional view of the immersion battery liquid cooling device of this utility model.

[0023] Figure 3 This is a top view of the infusion tube of this utility model.

[0024] In the diagram: 1. Shell; 11. Return port; 12. Exhaust port; 2. Battery; 201. Gap; 3. Cooling pipe; 4. Gas supply pipe; 41. Branch pipe; 42. Main pipe; 401. Air hole; 5. Bubble generator; 6. Gas storage tank; 7. Gas-liquid separator; 8. Liquid storage tank; 9. Transfer pump. Detailed Implementation

[0025] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0026] like Figure 1 As shown, combined with Figure 2 The present invention relates to an immersion liquid-cooled battery cooling device, comprising a housing 1, a cooling pipe 3, a gas supply pipe 4, a bubble generating device 5, and a gas storage tank 6.

[0027] The housing 1 contains several batteries 2, which are filled with a thermally conductive medium that submerges the batteries 2. The thermally conductive medium is either a hydrocarbon oil-based insulating liquid or a fluorinated hydrogen-based insulating liquid. Because the thermally conductive medium is either a hydrocarbon oil-based insulating liquid or a fluorinated hydrogen-based insulating liquid, an exhaust port 12 is provided at the top of the housing 1 to discharge air above the liquid surface.

[0028] Cooling pipe 3 is disposed inside the housing 1 and located at the top of the battery 2, and is immersed in the liquid surface of the heat-conducting medium. Coolant flows through cooling pipe 3, and can be water-cooled or oil-cooled. Cooling pipe 3 adopts a coil structure.

[0029] The gas supply pipe 4 is installed inside the housing 1 and located at the bottom of the battery 2. The gas supply pipe 4 is provided with air holes 401.

[0030] Clean air is stored in the gas storage tank 6. Specifically, inert gases such as nitrogen can be used.

[0031] A bubble generator 5 is connected between the gas storage tank 6 and the gas delivery pipe 4. The bubble generator 5 delivers high-pressure gas flow to the heat transfer medium from bottom to top through the gas port 401. The bubble generator 5 can be a compressor, and a one-way valve is installed at the outlet of the compressor to prevent the heat transfer medium inside the casing 1 from flowing into the compressor. In addition, a one-way valve needs to be installed between the bubble generator 5 and the gas delivery pipe 4 to prevent the heat transfer medium from flowing back into the bubble generator 5 through the gas delivery pipe 4.

[0032] When the above technical solution is adopted, the high-pressure gas is generated by the bubble generator 5 and then injected from the bottom to the top of the gap 201 of the battery 2 through the gas pipe 4 and the gas hole 401 to form a high-pressure bubble flow channel. After the high-pressure gas flows into the gap 201 flow channel of the battery 2, it will cause a large disturbance to the heat-conducting medium fluid in the flow channel, thereby destroying the thermal boundary layer formed on the surface of the battery 2 due to the low-speed flow state of the heat-conducting medium caused by its oiliness and viscosity, etc., thereby greatly improving the convective heat transfer coefficient of the heat-conducting medium on the surface of the battery 2, improving the heat dissipation capacity of the heat conduction mechanism on the side of the battery 2, and meeting the large heat dissipation requirements of the battery 2 during high-rate charging and discharging.

[0033] exist Figure 2 In a preferred embodiment shown, since the high-pressure gas carries some heat-conducting medium out of the exhaust port 12, the outflowing gas cannot directly enter the gas storage tank 6 and needs to be separated into gas and liquid. Therefore, this embodiment also includes a gas-liquid separation device 7.

[0034] A return port 11 is provided on the side wall of the shell 1 near the surface of the heat transfer medium.

[0035] A gas-liquid separator 7 is connected between the gas storage tank 6 and the exhaust port 12. The gas-liquid separator 7 can be a commercially available gas-liquid separator. It is also connected to the return port 11. The gas-liquid separator 7 collects the air discharged from the exhaust port 12. After separating the air into liquid and gas phases, the liquid phase is returned to the housing 1 through the return port 11, while the gas phase is transported back to the gas storage tank 6. The gas discharged from the exhaust port 12 first enters the gas-liquid separator 7 for gas-liquid separation. The separated gas phase is filtered and flows into the gas storage tank 6, while the separated liquid phase flows back into the housing 1.

[0036] exist Figure 2 In a preferred embodiment shown, a gap 201 is left between several batteries 2, and several air holes 401 arranged on each gas pipe 4 are arranged in a row, or several air holes 401 at corresponding positions on each gas pipe 4 are arranged in a row. Each row of air holes 401 is aligned with the gap 201 so that the high-pressure gas will not be obstructed and its ejection flow rate will not be reduced when it is ejected from the air hole 401.

[0037] exist Figure 2 In a preferred embodiment shown, the temperature difference between the surface of the battery 2 and the heat-conducting medium is adjusted by adjusting the width of the gap 201. In fluid mechanics, the Rayleigh number (Ra) of a fluid is a dimensionless number related to buoyancy-driven convection (also known as free convection or natural convection). When the Rayleigh number of a fluid is below a critical value, the main form of heat transfer is conduction; when the Rayleigh number exceeds the critical value, the main form of heat transfer is convection. The Rayleigh number is proportional to the cross-sectional area of ​​the fluid. Therefore, given a fixed length and width of the casing 1, the denser the batteries 2 are arranged inside the casing 1, the smaller the cross-sectional area of ​​the fluid; conversely, the more loosely arranged the batteries 2 are, the larger the cross-sectional area of ​​the fluid. Thus, the Rayleigh number of the heat-conducting medium can be changed by adjusting the width of the gap 201, i.e., the temperature difference between the surface of the battery 2 and the heat-conducting medium can be adjusted.

[0038] exist Figure 2 In a preferred embodiment shown, the formula for calculating the width of the gap 201 is:

[0039] S=CL×(gβ△TL 3 / αv) 0.25 (1)

[0040] Where C is an empirical constant, usually determined experimentally, L is the height of battery 2, g is the gravitational acceleration, β is the thermal expansion coefficient of the heat-conducting medium, ΔT is the temperature difference between the surface of battery 2 and the heat-conducting medium, α is the thermal diffusivity of the heat-conducting medium, and v is the viscosity of the immersion coolant.

[0041] The derivation process of the above calculation formula (1) is as follows:

[0042] First, we assume: 1) The fluid is laminar: Reynolds number is low in natural convection, so the flow is usually assumed to be laminar; 2) Thermal boundary layers do not overlap: The thermal boundary layers of adjacent fins should just touch but not overlap to balance heat dissipation area and flow resistance; 3) Thermal drive is dominant: Buoyancy (caused by temperature difference) is the main driving force of fluid flow.

[0043] Then, based on the above assumptions, the thermal boundary layer thickness can be estimated. In natural convection on a vertical flat plate, the typical expression for the thermal boundary layer thickness δ is:

[0044] δ= L×Ra 0.25 (2)

[0045] The boundary layer thickness decreases as the Rayleigh number increases because stronger buoyancy accelerates fluid flow and compresses the boundary layer.

[0046] Next, the optimal width of gap 201 is derived. Since the boundary layer does not overlap as an assumption, the optimal spacing S should satisfy the condition that the boundary layers of adjacent ribs are exactly in contact, that is,

[0047] S=2δ, (3)

[0048] Substituting equation (2) into equation (3) yields the following equation:

[0049] S = 2L × Ra 0.25 (4)

[0050] Finally, an experimental correction factor is introduced. Through experiments and numerical simulations, it is found that the actual optimal spacing requires a correction factor, which also influences the Rayleigh number calculation formula.

[0051] Ra=gβ△TL 3 / αv, (5)

[0052] The final equation is (1), where C is 2.714. Therefore, the greater the temperature difference, the thinner the boundary layer, and the denser the fins are required. High-viscosity fluids have high flow resistance, requiring larger spacing to avoid flow blockage.

[0053] exist Figure 2 In a preferred embodiment shown, the width of the gap 201 is no greater than 10 cm.

[0054] exist Figure 3 In a preferred embodiment shown, the gas supply pipe 4 includes branch pipes 41 and main pipe 42. A plurality of branch pipes 41 are arranged in each gap 201 in a corresponding manner, and a plurality of air holes 401 are arranged on the branch pipes 41. The main pipe 42 is connected to one end of one of the branch pipes 41. One end of the main pipe 42 extends through the shell 1 to the external environment. The outer end of the main pipe 42 is connected to the gas storage tank 6 through the bubble generating device 5.

[0055] exist Figure 3 In a preferred embodiment shown, the diameter of the pore 401 is 1-2 cm, and the spacing between adjacent pores 401 is 3-5 cm. The size and spacing of the pores 401 will have a certain impact on the destructive effect of the high-pressure gas on the thermal boundary.

[0056] exist Figure 2 In a preferred embodiment shown, the liquid storage tank 8 and the transfer pump 9 are also included.

[0057] The liquid storage tank 8 is connected to the output and input ends of the cooling pipe 3, and the liquid storage tank 8 contains cooling water or cooling oil.

[0058] The transfer pump 9 is connected between the liquid storage tank 8 and the input end of the cooling pipe 3, and pumps cooling water into the heat exchange pipe. The transfer pump 7 is a water pump or an oil pump.

[0059] like Figure 1 As shown, combined with Figure 2 An energy storage battery pack employs the aforementioned immersion liquid cooling battery cooling device.

[0060] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An immersion liquid-cooled battery cooling device, characterized by: The shell (1), the cooling pipe (3), the gas pipe (4), the bubble generating device (5) and the air storage tank (6) are included. A plurality of batteries (2) are arranged in the shell (1), the shell (1) is filled with heat-conducting medium and the batteries (2) are immersed in the heat-conducting medium, an air outlet (12) is arranged at the top of the shell (1), and the air outlet (12) discharges air above the liquid level of the shell (1). The cooling pipe (3) is arranged in the shell (1) and located at the top of the batteries (2), and the cooling pipe (3) is immersed below the liquid level of the heat-conducting medium. The gas pipe (4) is arranged in the shell (1) and located at the bottom of the batteries (2), and a plurality of air holes (401) are arranged on the gas pipe (4). The air storage tank (6) stores clean air. The bubble generating device (5) is connected between the air storage tank (6) and the gas pipe (4), and the bubble generating device (5) sends high-pressure gas flow to the heat-conducting medium from bottom to top through the air holes (401).

2. The submersion liquid-cooled battery cooling device of claim 1, wherein: Further comprising a gas-liquid separation device (7). A backflow port (11) is arranged on the side wall of the shell (1) near the liquid level of the heat-conducting medium. The gas-liquid separation device (7) is connected between the air storage tank (6) and the air outlet (12), and the gas-liquid separation device (7) is also connected with the backflow port (11), the gas-liquid separation device (7) collects air discharged from the air outlet (12), and the gas-liquid separation device (7) separates the air into liquid phase and gas phase, and then sends the liquid phase back to the shell (1) through the backflow port (11) and sends the gas phase to the air storage tank (6).

3. The submersion liquid-cooled battery cooling device of claim 2, wherein: A plurality of gaps (201) are arranged between the batteries (2), a plurality of air holes (401) arranged on each gas pipe (4) form a row, or a plurality of air holes (401) arranged on each gas pipe (4) and corresponding in position form a row, and each row of air holes (401) is arranged in alignment with the gaps (201).

4. The submersion liquid-cooled battery cooling device of claim 3, wherein: The temperature difference between the surface of the battery (2) and the heat-conducting medium is adjusted by adjusting the width of the gap (201).

5. The submersion liquid-cooled battery cooling device of claim 4, wherein: The calculation formula of the width of the gap (201) is, S = CL x (gβ△TL 3 / αv) 0.25 , Wherein, C is an empirical constant, L is the height of the battery (2), g is the acceleration of gravity, β is the thermal expansion coefficient of the heat-conducting medium, ΔT is the temperature difference between the surface of the battery (2) and the heat-conducting medium, α is the thermal diffusion coefficient of the heat-conducting medium, and v is the viscosity of the immersed cooling liquid.

6. The submersion liquid-cooled battery cooling apparatus of claim 4, wherein: The width of the gap (201) is not greater than 10 cm.

7. The submersion liquid-cooled battery cooling device of claim 3, wherein: The gas pipe (4) includes branch pipes (41) and a main pipe (42), A plurality of branch pipes (41) are arranged in each gap (201) one by one, and a plurality of air holes (401) are arranged on the branch pipes (41); The main pipe (42) is connected with one end of a plurality of branch pipes (41) at the same time, one end of the main pipe (42) extends to the outside environment through the shell (1), and the outer end of the main pipe (42) is connected with the air storage tank (6) through the bubble generating device (5).

8. The submersion liquid-cooled battery cooling apparatus of claim 1, wherein: The diameter of the air hole (401) is 1-2 cm, and the distance between adjacent air holes (401) is 3-5 cm.

9. The submersion liquid-cooled battery cooling apparatus of claim 1, wherein: Further comprising a liquid storage tank (8) and a delivery pump (9). The storage tank (8) is connected with the output end and the input end of the cooling pipe (3), and the storage tank (8) stores cooling water; The delivery pump (9) is connected between the storage tank (8) and the input end of the cooling pipe (3), and the delivery pump (9) pumps the cooling water to the heat exchange pipe.

10. An energy storage battery pack characterized by: An immersed liquid-cooled battery cooling device according to any one of claims 1 to 9.

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