An immersed energy storage battery pack and methods of use thereof

Abstract

The application provides an immersed energy storage battery pack and a use method thereof, and belongs to the field of energy storage battery packs. The immersed energy storage battery pack comprises a shell filled with immersed liquid; a cover plate is arranged on the top of the shell; a liquid cooling pipe is arranged below the liquid level of the immersed liquid; a gap is arranged between the liquid level of the immersed liquid and the lower surface of the cover plate; a gas hole is horizontally arranged on the lower surface of the cover plate and is flush with the liquid level of the immersed liquid; a recovery port is horizontally arranged on the top of the side wall of the shell and is flush with the liquid level of the immersed liquid and is aligned with the gas hole; the gas hole and the recovery port are communicated with the gap; the gas hole blows gas to the bubbles floating on the liquid level of the immersed liquid and pushes the bubbles to move to the recovery port. The gas hole blows away the bubbles on the liquid level and makes the bubbles flow to the recovery port, so that the bubbles on the liquid level are effectively blown away and eliminated, the effect of the contact between the immersed liquid and the liquid cooling pipe is avoided, the air pressure in the gap is reduced by eliminating the bubbles, and the swelling and explosion of the battery pack are avoided.

Description

Technical Field

[0001] This invention relates to the field of energy storage battery pack technology, and in particular to an immersion energy storage battery pack and its usage method. 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] However, a common problem with current immersion cooling systems is that the immersion fluid generates numerous tiny bubbles during the heating process. These bubbles rise to the surface of the fluid as its density decreases, accumulating on the surface. The presence of these bubbles not only affects the contact between the immersion fluid and the liquid cooling plate but also increases the pressure inside the battery pack, potentially causing it to burst. Current solutions involve adding defoaming agents to the immersion fluid, but these agents, in turn, reduce the fluid's heat exchange performance. Summary of the Invention

[0004] In view of this, the present invention proposes an immersion energy storage battery pack and its usage method to solve the problem that air bubbles on the surface of the immersion liquid not only affect the contact effect between the immersion liquid and the liquid cooling plate, but also increase the pressure inside the battery pack, leading to the battery pack bursting.

[0005] The technical solution of this invention is implemented as follows: This invention provides an immersion energy storage battery pack, including a shell with an open top and filled with immersion liquid; a cover plate, which covers the top of the shell and forms a closed space with the shell; and a liquid cooling pipe, which is hung below the cover plate and located below the surface of the immersion liquid; wherein, a gap is left between the surface of the immersion liquid and the lower surface of the cover plate; a vent is horizontally opened on the lower surface of the cover plate, and the vent is flush with the surface of the immersion liquid; a recovery port is horizontally opened on the top of the side wall of the shell, which is flush with the surface of the immersion liquid and aligned with the vent, and both the vent and the recovery port are connected to the gap; the vent blows air onto the air bubbles floating on the surface of the immersion liquid and pushes the air bubbles toward the recovery port.

[0006] Based on the above technical solutions, preferably, the system also includes a gas delivery mechanism disposed outside the housing; a liquid storage tank disposed outside the housing and storing the immersion liquid; and a delivery pump. The housing has a liquid inlet at its bottom. The gas delivery mechanism is connected to a gas vent and delivers gas to the vent. The liquid storage tank is connected at both ends to a recovery port and a liquid inlet, respectively. One-way valves are installed between the liquid storage tank and the recovery port, and between the liquid storage tank and the liquid inlet, to allow the immersion liquid to flow unidirectionally from the recovery port into the liquid storage tank, and to allow the immersion liquid to flow unidirectionally from the liquid storage tank into the liquid inlet. The delivery pump is connected between the liquid storage tank and the liquid inlet, and pumps the immersion liquid from the liquid storage tank into the housing.

[0007] More preferably, a number of pores are arranged horizontally and linearly, with a pore diameter of 0.5-1.0 mm and a spacing of 5-8 mm between adjacent pores.

[0008] More preferably, the output pressure of the gas transmission mechanism is 0.1-0.3MPa, and the transmission flow rate of the gas transmission mechanism is 8-15L / min.

[0009] More preferably, it also includes a pressure sensor disposed on the lower surface of the cover plate and located within the gap; wherein the pressure sensor is used to detect pressure changes within the gap.

[0010] More preferably, a cavity is formed above the surface of the immersion liquid stored in the storage tank, and a delivery pipe is connected between the top of the storage tank and the recovery port. The end of the delivery pipe passes through the storage tank and is inserted into the cavity. An exhaust port is provided on the side of the top of the storage tank, which is connected to the cavity. An air extraction mechanism is connected to the exhaust port, which extracts air outward through the exhaust port and creates a negative pressure state inside the cavity.

[0011] Based on the above technical solutions, preferably, the lower surface of the cover plate is set as an inclined surface, and the distance between the end of the inclined surface near the recovery port and the surface of the immersion liquid is greater than the distance between the end of the inclined surface away from the recovery port and the surface of the immersion liquid.

[0012] More preferably, the angle of inclination of the inclined plane relative to the horizontal plane is no greater than 5 degrees.

[0013] More preferably, the two ends of the inclined surface extend along the length of the shell.

[0014] On the other hand, the present invention also provides a method for using an immersion energy storage battery pack. The method includes the following steps: Step 1, a battery is loaded into the casing and immersed in an immersion liquid. The battery heats up, causing bubbles to form in the immersion liquid and rise to the surface, filling the gaps. At this point, a pressure sensor detects an increase in pressure within the gaps, and the gas supply mechanism and the gas extraction mechanism are activated. Step 2, the gas supply mechanism blows air onto the liquid surface through air holes, causing the bubbles to flow towards the recovery port. The gas extraction mechanism creates a negative pressure environment within the cavity and draws air from the recovery port. Step 3, a pressure sensor detects a decrease in pressure within the gaps, and the gas supply mechanism and the gas extraction mechanism are shut off.

[0015] The submersible energy storage battery pack and its method of use of the present invention have the following advantages over the prior art:

[0016] (1) The present invention blows away the air bubbles on the liquid surface through the air hole and makes the air bubbles flow towards the recovery port, which can effectively blow away and eliminate the air bubbles on the liquid surface, thus avoiding the air bubbles from affecting the contact effect between the immersion liquid and the liquid cooling pipe. At the same time, by eliminating the air bubbles, the air pressure in the gap can also be reduced, thereby preventing the battery pack from bulging and bursting.

[0017] (2) The present invention sets the lower surface of the cover plate as an inclined surface, which can fill the shell with the immersion liquid as much as possible and reduce the surface area of ​​the immersion liquid, so that the bubbles can be gathered together. This not only helps to fully blow away the bubbles, but also reduces the space volume of the gap, increases the filling ratio of the immersion liquid and reduces the impact of pressure changes in the gap on the battery pack. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a perspective view of the battery pack of the present invention;

[0020] Figure 2 This is a side sectional view of the battery pack of the present invention;

[0021] Figure 3 For the present invention Figure 2 Enlarged view of point A in the middle;

[0022] Figure 4 For the present invention Figure 2 Enlarged view of point B in the middle.

[0023] In the diagram: 1. Shell; 100. Gap; 101. Recovery port; 102. Liquid inlet; 2. Cover plate; 201. Air hole; 202. Inclined surface; 3. Liquid cooling pipe; 4. Gas delivery mechanism; 5. Liquid storage tank; 501. Cavity; 502. Exhaust port; 6. Delivery pump; 7. Pressure sensor; 8. Delivery pipe; 9. Vacuuming mechanism. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, combined with Figure 2 The present invention provides an immersion energy storage battery pack, comprising a housing 1, a cover plate 2, and a liquid cooling pipe 3.

[0026] The casing 1 is open at the top and filled with an immersion liquid. Air bubbles float on the surface of the immersion liquid, and a gap 100 exists between the liquid surface and the lower surface of the cover plate 2, thus the air bubbles are located within this gap. The immersion liquid is typically an insulating liquid containing fluorinated carbon compounds, with a dielectric strength ≥40kV / 2.5mm. The surface tension of the immersion liquid is generally no greater than that of water (i.e., <72mN / m).

[0027] The cover plate 2 is placed on top of the housing 1 and forms a closed space with the housing 1. The lower surface of the cover plate 2 has a horizontally opened air hole 201, which is flush with the liquid surface of the immersion liquid; the top of the side wall of the housing 1 has a horizontally opened recovery port 101, which is flush with the liquid surface of the immersion liquid and aligned with the air hole 201. Both the recovery port 101 and the air hole 201 are connected to the gap 100.

[0028] The liquid cooling pipe 3 is suspended below the cover plate 2 and located below the surface of the immersion liquid; a cooling medium flows through the liquid cooling pipe 3; the liquid cooling pipe 3 adopts a serpentine multi-channel structure to increase the flow length and flow time of the cooling medium, thereby improving the heat exchange efficiency between the liquid cooling pipe 3 and the immersion liquid. The cooling medium is a 50% ethylene glycol pure aqueous solution. Ethylene glycol pure aqueous solution has a higher specific heat capacity and can absorb more heat, which is conducive to heat exchange and cooling.

[0029] When the above technical solution is adopted, several batteries are arranged in a matrix and loaded in the casing 1 and completely immersed in the immersion liquid. The heat generated by the batteries will cause the immersion liquid to absorb heat. According to the principle of thermal expansion and contraction, the immersion liquid will absorb heat and its density will decrease. Therefore, the immersion liquid with high temperature at the bottom will rise to the top, while the immersion liquid with low temperature at the top will sink to the bottom due to its higher density. At the same time, the high temperature immersion liquid will also sink back to the bottom after heat exchange and cooling with the liquid cooling pipe 3 located at the top of the battery. In this way, the convection circulation inside the immersion liquid is realized. During the convection circulation process, although the surface tension of the immersion liquid is lower than that of water, it is still difficult to avoid the generation of bubbles. The accumulation of a large number of tiny bubbles will reduce the contact area between the immersion liquid and the liquid cooling pipe, and will also increase the internal pressure of the battery pack. Moreover, because the surface tension is lower, the bubbles generated are more numerous and finer, making them more difficult to eliminate. To address this issue, the solution adopts the method of blowing air onto the surface of the immersion liquid through the air hole 201 and pushing the bubbles toward the recovery port 101. By blowing the purging air into the recovery port 101, the bubbles on the surface of the immersion liquid are removed as much as possible.

[0030] exist Figure 2 In a preferred embodiment shown, the system further includes a gas delivery mechanism 4, a liquid storage tank 5, and a delivery pump 6.

[0031] The bottom of the shell 1 is provided with a liquid inlet 102.

[0032] The gas delivery mechanism 4 is located outside the housing 1. The gas delivery mechanism 4 is connected to the air vent 201 and delivers airflow to the air vent 201. The gas delivery mechanism 4 can be a small air pump.

[0033] The storage tank 5 is located outside the housing 1 and stores the submerged liquid. Since the function of the storage tank 5 is to temporarily store the submerged liquid so that a small amount of recovered submerged liquid can flow back into the housing 1, the storage tank 5 is typically a small tank, not requiring a large space in the energy storage battery pack. The two ends of the storage tank 5 are connected to the recovery port 101 and the inlet port 102, respectively. One-way valves are installed between the storage tank 5 and the recovery port 101, and between the storage tank 5 and the inlet port 102, respectively, allowing the submerged liquid to flow unidirectionally from the recovery port 101 into the storage tank 5, and from the storage tank 5 into the inlet port 102.

[0034] The transfer pump 6 is connected between the storage tank 5 and the inlet 102. The transfer pump 6 pumps the immersion liquid in the storage tank 5 into the housing 1.

[0035] When the above technical solution is adopted, the air hole 201 blows the air bubbles into the recovery port 101, so that the air bubbles, along with a small amount of immersion liquid, enter the storage tank 5 through the recovery port 101 for recovery. After the air bubbles naturally defoam in the storage tank 5, they can be pumped back into the housing 1 by the transfer pump 6, so as to avoid the reduction of the total amount of immersion liquid in the housing 1 and the resulting pressure change in the battery pack.

[0036] exist Figure 3 In a preferred embodiment shown, several vents 201 are arranged horizontally and linearly, thereby effectively sweeping away bubbles across the entire liquid surface. The gas velocity can be calculated using Bernoulli's equation, i.e., gas velocity v = √(2ΔP / ρ). Assuming that the thrust required to move the bubbles in an open environment is ΔP = 0.1 MPa, and the air density is ρ ≈ 1.2 kg / m³,... 3 We can calculate that v≈129m / s. However, it is foreseeable that the required airflow velocity for the purge bubble movement in the battery pack design will be much smaller than this theoretical value; for example, the required airflow velocity may only be 0.1-0.5m / s. Therefore, it is necessary to limit the airflow of the purge bubble by restricting the aperture of the vent 201. Then, according to the actual effective flow velocity correction formula Q=n·A·v eff Assuming the flow rate of the bubble moving with the immersion liquid is Q = 10 L / min, and assuming the required flow rate v of pore 201... eff ≈0.85m / s. Assuming the number of pores 201 n=50, the radial cross-section A of pore 201 can be calculated, and the pore diameter of pore 201 can be converted to approximately 1.0mm. Therefore, it is reasonable to limit the pore diameter D of pore 201 to 0.5-1.0mm in this scheme. At the same time, the arrangement spacing S of several pores 201 can satisfy the empirical formula S≤2√(v·t·D), where t is the bubble detachment time and is assumed to be approximately 0.1s. Then it can be known that the spacing S of adjacent pores 201 ≤7.8mm. It is reasonable for this scheme to limit the range to 5-8mm.

[0037] exist Figure 2 In a preferred embodiment shown, the output pressure of the gas delivery mechanism 4 is 0.1-0.3 MPa, and the delivery flow rate of the gas delivery mechanism 4 is 8-15 L / min. Since the vent 201 is flush with the surface of the immersion liquid, a small amount of immersion liquid may enter the vent 201 and cause blockage under the action of capillary action. Therefore, it is necessary to provide a certain pressure and flow rate through the gas delivery mechanism 4 to blow out the immersion liquid in the vent 201.

[0038] exist Figure 3 In a preferred embodiment shown, a pressure sensor 7 is also included. The pressure sensor 7 is disposed on the lower surface of the cover plate 2 and located within the gap 100. The pressure sensor 7 detects the pressure change within the gap 100 in real time, thereby indirectly monitoring the accumulation of air bubbles within the gap 100 and controlling the opening and closing of the gas delivery mechanism 4.

[0039] exist Figure 4In a preferred embodiment shown, in addition to the airflow through the vent 201 blowing the bubbles towards the recovery port 101, the recovery port 101 also needs to have a certain negative pressure suction to fully draw in the bubbles and a small amount of submerged liquid and bring them into the storage tank 5. Therefore, a cavity 501 is formed above the liquid surface of the submerged liquid stored in the storage tank 5. A delivery pipe 8 is connected between the top of the storage tank 5 and the recovery port 101, and the end of the delivery pipe 8 passes through the storage tank 5 and is inserted into the cavity 501. An exhaust port 502 is provided on the side of the top of the storage tank 5. The exhaust port 502 is connected to the cavity 501, and a suction mechanism 9 is connected to the exhaust port 502. The suction mechanism 9 draws air out through the exhaust port 502 and creates a negative pressure state inside the cavity 501. The negative pressure state of the cavity 501 forces the recovery port 101 to generate suction to draw away the bubbles and a small amount of submerged liquid. Meanwhile, the immersion liquid in the storage tank 5 is pumped back to the shell 1 through its bottom outlet, which avoids the return of air bubbles that may remain on the surface of the liquid in the storage tank 5 without natural defoaming to the shell 1.

[0040] exist Figure 2 In a preferred embodiment shown, the lower surface of the cover plate 2 is configured as a slope 202. The distance between the end of the slope 202 near the recovery port 101 and the surface of the immersion liquid is greater than the distance between the end of the slope 202 away from the recovery port 101 and the surface of the immersion liquid. The slope 202 makes the gap 100 form a triangle that is smaller at the top and larger at the bottom. Since the recovery port 101 is close to the top of the gap 100, the immersion liquid can fill the housing 1 as much as possible and reduce the surface area of ​​the immersion liquid, so that the air bubbles can be gathered together, which helps to fully purge and remove the air bubbles. At the same time, it also minimizes the spatial volume of the gap 100, increases the filling ratio of the immersion liquid, and reduces the impact of pressure changes in the gap on the battery pack.

[0041] exist Figure 3 In a preferred embodiment shown, the inclination angle of the inclined plane 202 relative to the horizontal plane is no greater than 5 degrees. The inclination angle of the inclined plane 202 should not be too large, otherwise it will significantly compress the internal volume of the battery pack and increase the overall thickness of the battery pack.

[0042] exist Figure 2 In a preferred embodiment shown, the two ends of the inclined surface 202 extend along the length of the housing 1, which also helps to reduce the spatial volume of the gap 100.

[0043] like Figure 1 As shown, combined with Figure 2 The present invention provides a method for using an immersed energy storage battery pack, employing any of the above embodiments of an immersed energy storage battery pack, comprising the following steps:

[0044] Step 1: The battery is installed in the casing 1 and immersed in the immersion liquid. The battery heats up, causing bubbles to form in the immersion liquid and float to the surface of the immersion liquid, filling the gap 100 with bubbles. At this time, the pressure sensor 7 detects that the pressure in the gap 100 has increased, and the gas supply mechanism 4 and the gas extraction mechanism 9 are started.

[0045] Step 2: The gas delivery mechanism 4 blows air onto the liquid surface through the air hole 201 and causes the air bubbles to flow towards the recovery port 101; the air extraction mechanism 9 creates a negative pressure environment in the cavity 501 and causes the recovery port 101 to draw in the air bubbles.

[0046] Step 3: The pressure sensor 7 detects a decrease in pressure within gap 100, and shuts off the gas supply mechanism 4 and the gas extraction mechanism 9.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An immersed energy storage battery pack, characterized by, The utility model relates to a liquid cooling device, including: a shell (1) which is open at the top and filled with immersion liquid; a cover plate (2) which covers the top of the shell (1) and forms an enclosed space with the shell (1); a liquid cooling pipe (3) which is hung below the cover plate (2) and below the liquid level of the immersion liquid; a gas delivery mechanism (4) which is arranged outside the shell (1); a liquid storage tank (5) which is arranged outside the shell (1) and stores immersion liquid; a delivery pump (6); wherein a gap (100) is left between the liquid level of the immersion liquid and the lower surface of the cover plate (2); the lower surface of the cover plate (2) is horizontally provided with a gas hole (201) which is flush with the liquid level of the immersion liquid; the top of the side wall of the shell (1) is horizontally provided with a recovery port (101) which is flush with the liquid level of the immersion liquid and aligned with the gas hole (201), the gas hole (201) and the recovery port (101) are both in communication with the gap (100), and the bottom of the shell (1) is provided with a liquid inlet (102); the lower surface of the cover plate (2) is provided as an inclined surface (202), the distance between the inclined surface (202) near one end of the recovery port (101) and the liquid level of the immersion liquid is greater than the distance between the inclined surface (202) away from the other end of the recovery port (101) and the liquid level of the immersion liquid; the gas hole (201) blows gas to the gas bubbles floating on the liquid level of the immersion liquid and pushes the gas bubbles to move towards the recovery port (101); the gas delivery mechanism (4) is in communication with the gas hole (201), and the gas delivery mechanism (4) delivers gas flow to the gas hole (201); the liquid storage tank (5) is in communication with the recovery port (101) and the liquid inlet (102) at both ends, respectively, and one-way valves are arranged between the liquid storage tank (5) and the recovery port (101) and between the liquid storage tank (5) and the liquid inlet (102), respectively, so that the immersion liquid flows from the recovery port (101) to the liquid storage tank (5) in one direction and the immersion liquid flows from the liquid storage tank (5) to the liquid inlet (102) in one direction; the delivery pump (6) is connected between the liquid storage tank (5) and the liquid inlet (102), and the delivery pump (6) pumps the immersion liquid in the liquid storage tank (5) into the shell (1).

2. The submerged energy storage battery pack of claim 1, wherein: A plurality of the gas holes (201) are arranged horizontally and linearly, the diameter of the gas hole (201) is 0.5-1.0 mm, and the distance between adjacent gas holes (201) is 5-8 mm.

3. The submerged energy storage battery pack of claim 2, wherein: The output pressure of the gas delivery mechanism (4) is 0.1-0.3 MPa, and the delivery flow rate of the gas delivery mechanism (4) is 8-15 L / min.

4. The submerged energy storage battery pack of claim 1, wherein, Further including: a pressure sensor (7) which is arranged on the lower surface of the cover plate (2) and located in the gap (100); wherein the pressure sensor (7) is used to detect the pressure change in the gap (100).

5. The submerged energy storage battery pack of claim 4, wherein: An empty cavity (501) is formed above the liquid level of the immersion liquid stored in the liquid storage tank (5), a delivery pipe (8) is in communication between the top of the liquid storage tank (5) and the recovery port (101), and the end of the delivery pipe (8) penetrates through the liquid storage tank (5) and is inserted into the empty cavity (501). The side of the top of the liquid storage tank (5) is provided with an exhaust port (502), the exhaust port (502) is communicated with the cavity (501), the exhaust port (502) is connected with the air extraction mechanism (9), the air extraction mechanism (9) extracts air outward through the exhaust port (502) and forms a negative pressure state in the cavity (501).

6. The submerged energy storage battery pack of claim 1, wherein: The inclination angle of the inclined surface (202) relative to the horizontal plane is not greater than 5 degrees.

7. The submerged energy storage battery pack of claim 1, wherein: The two ends of the inclined surface (202) extend along the length direction of the shell (1).

8. A method of using an immersed energy storage battery pack, characterized by: The submerged energy storage battery pack of claim 5 comprises the following steps, Step one, the shell (1) is loaded with batteries, and the batteries are immersed in the immersion liquid, the battery heating forms bubbles in the immersion liquid and floats to the liquid surface of the immersion liquid, the gap (100) is filled with the bubbles, at this time, the pressure sensor (7) detects that the pressure in the gap (100) increases, and the air conveying mechanism (4) and the air extraction mechanism (9) are started; Step two, the air conveying mechanism (4) blows air to the liquid surface through the air hole (201), and the bubbles flow to the recovery port (101); the air extraction mechanism (9) forms a negative pressure environment in the cavity (501), and the recovery port (101) sucks the bubbles; Step three, the pressure sensor (7) detects that the pressure in the gap (100) decreases, and the air conveying mechanism (4) and the air extraction mechanism (9) are closed.

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