Immersed energy storage battery pack and use method thereof

Abstract

The invention provides an immersed energy storage battery pack and a use method thereof, and belongs to the field of energy storage battery packs. The cover plate covers the top of the shell; the liquid cooling pipe is located below the liquid level of the immersion liquid; a gap is reserved between the liquid level of the immersion liquid and the lower surface of the cover plate; an air hole is horizontally formed in the lower surface of the cover plate and is flush with the liquid level of the immersion liquid; a recovery opening is horizontally formed in the top of the side wall of the shell, the recovery opening is flush with the liquid level of the immersion liquid and is aligned to the air hole, and the air hole and the recovery opening are both communicated with the gap; the air hole blows air to bubbles floating on the liquid level of the immersion liquid and pushes the bubbles to move towards the recovery opening. Bubbles on the liquid level are purged through the air holes and flow towards the recovery opening, the bubbles on the liquid level can be effectively blown away and eliminated, the situation that the bubbles affect the contact effect of immersion liquid and the liquid cooling pipe is avoided, meanwhile, the air pressure in the gap can be reduced by eliminating the bubbles, and therefore the battery pack is prevented from bulging and bursting.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage battery packs, and in particular to an immersion-type energy storage battery pack and a method for using the same. Background Art

[0002] In recent years, with the rapid development of electrochemical energy storage technology, immersion liquid cooling energy storage systems have gradually become the mainstream design solution for large-capacity battery packs due to their high heat dissipation capacity and intrinsic safety. For example, in Tesla patent US20210083221A1, a thermal cycle of upward and downward convection of the immersion liquid is formed by the density difference of the immersion liquid caused by battery heating. Specifically, when the immersion liquid is heated and its temperature rises, its density becomes smaller. Therefore, the high-temperature immersion liquid rises and contacts the liquid cooling plate arranged at the top of the immersion liquid. After heat exchange with the liquid cooling plate, the high-temperature immersion liquid cools down and then descends back to the bottom again.

[0003] However, the common problem of current immersion cooling systems is that many tiny bubbles will be generated during the heating process of the immersion liquid. The bubbles float upward with the high-temperature immersion liquid whose density becomes smaller and gather on the liquid surface of the immersion liquid. The presence of bubbles not only affects the contact effect between the immersion liquid and the liquid cooling plate, but also increases the pressure inside the battery pack, resulting in the explosion of the battery pack. The current solution is to add an antifoaming substance to the immersion liquid, but the antifoaming substance will reduce the heat exchange performance of the immersion liquid. Summary of the Invention

[0004] In view of this, the present invention provides an immersion-type energy storage battery pack and a method for using the same, which are used to solve the problem that the bubbles existing on the liquid 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, resulting in the explosion of the battery pack.

[0005] The technical solution of the present invention is realized as follows: The present invention provides an immersion-type energy storage battery pack, including a housing with an open top and filled with an immersion liquid inside; a cover plate covering the top of the housing and enclosing a closed space with the housing; a liquid cooling pipe hanging below the cover plate and located below the liquid surface of the immersion liquid; wherein, there is a gap between the liquid surface of the immersion liquid and the lower surface of the cover plate; the lower surface of the cover plate is horizontally provided with air holes, and the air holes are flush with the liquid surface of the immersion liquid; a recovery port is horizontally provided at the top of the side wall of the housing, and the recovery port is flush with the liquid surface of the immersion liquid and aligned with the air holes, and both the air holes and the recovery port are communicated with the gap; the air holes blow air to the bubbles floating on the liquid surface of the immersion liquid and push the bubbles to move towards the recovery port.

[0006] Based on the above technical solutions, preferably, it further includes a gas transmission mechanism arranged outside the housing; a liquid storage tank arranged outside the housing and storing immersion liquid; a delivery pump; wherein, a liquid inlet is opened at the bottom of the housing; the gas transmission mechanism is communicated with the air holes, and the gas transmission mechanism conveys air flow to the air holes; both ends of the liquid storage tank are respectively communicated with the recovery port and the liquid inlet, and one-way valves are respectively arranged between the liquid storage tank and the recovery port and between the liquid storage tank and the liquid inlet, so that the immersion liquid flows unidirectionally from the recovery port into the liquid storage tank, and the immersion liquid flows 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 the delivery pump pumps the immersion liquid in the liquid storage tank into the housing.

[0007] More preferably, a plurality of air holes are arranged horizontally and linearly, the aperture of the air holes is 0.5 - 1.0 mm, and the distance between adjacent air holes is 5 - 8 mm.

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

[0009] More preferably, it further includes a pressure sensor arranged on the lower surface of the cover plate and located in the gap; wherein, the pressure sensor is used to detect the pressure change in the gap.

[0010] More preferably, a cavity is formed above the liquid level of the immersion liquid stored in the liquid storage tank, a delivery pipe is communicated between the top of the liquid storage tank and the recovery port, and the end of the delivery pipe passes through the liquid storage tank and is inserted into the cavity; an exhaust port is opened on the side surface of the top of the liquid storage tank, the exhaust port is communicated with the cavity, and an air extraction mechanism is connected to the exhaust port, and the air extraction mechanism extracts air outward through the exhaust port and makes the inside of the cavity in a negative pressure state.

[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 close to the recovery port and the liquid level of the immersion liquid is greater than the distance between the end of the inclined surface far from the recovery port and the liquid level of the immersion liquid.

[0012] More preferably, the inclination angle of the inclined surface relative to the horizontal plane is not greater than 5 degrees.

[0013] More preferably, both ends of the inclined surface extend along the length direction of the housing.

[0014] On the other hand, the present invention also provides a method for using an immersion energy storage battery pack. By using the above-mentioned immersion energy storage battery pack, the method includes the following steps. Step 1: Load the battery into the housing and immerse the battery in the immersion liquid. The heat generated by the battery causes bubbles to form in the immersion liquid and float to the liquid surface of the immersion liquid. The gap is filled with bubbles. At this time, when the pressure sensor detects an increase in the pressure in the gap, the air supply mechanism and the air extraction mechanism are started. Step 2: The air supply mechanism blows air through the air holes towards the liquid surface and makes the bubbles flow towards the recovery port. The air extraction mechanism creates a negative pressure environment in the cavity and sucks the bubbles through the recovery port. Step 3: When the pressure sensor detects a decrease in the pressure in the gap, the air supply mechanism and the air extraction mechanism are closed.

[0015] The immersion energy storage battery pack and its usage method of the present invention have the following beneficial effects compared with the prior art:

[0016] (1) By blowing the bubbles on the liquid surface through the air holes and making the bubbles flow towards the recovery port, the present invention can effectively blow away and eliminate the bubbles on the liquid surface, avoiding the influence of the bubbles on the contact effect between the immersion liquid and the liquid cooling pipe. At the same time, by eliminating the bubbles, the air pressure in the gap can also be reduced, thereby avoiding the swelling and bursting of the battery pack.

[0017] (2) By setting the lower surface of the cover plate as an inclined surface, the present invention can make the immersion liquid fill the housing as much as possible and reduce the area of the immersion liquid surface, so that the bubbles can gather together. This not only helps to fully blow away and remove the bubbles, but also reduces the space volume of the gap, improves the filling ratio of the immersion liquid, and reduces the influence of the pressure change in the gap on the battery pack. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

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

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

[0021] Figure 3 For the present invention Figure 2 The enlarged view of part A in

[0022] Figure 4 For the present invention Figure 2 The enlarged view of part B in

[0023] In the figure: 1. Housing; 100. Gap; 101. Recovery port; 102. Liquid inlet; 2. Cover plate; 201. Air hole; 202. Inclined surface; 3. Liquid cooling pipe; 4. Gas transmission mechanism; 5. Liquid storage tank; 501. Cavity; 502. Exhaust port; 6. Delivery pump; 7. Pressure sensor; 8. Delivery pipe; 9. Air extraction mechanism. Specific implementation mode

[0024] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] As Figure 1 shown, in combination with Figure 2 , an immersion energy storage battery pack of the present invention includes a housing 1, a cover plate 2 and a liquid cooling pipe 3.

[0026] Among them, the top of the housing 1 is open and the inside is filled with immersion liquid. Bubbles float on the liquid surface of the immersion liquid. There is a gap 100 between the liquid surface of the immersion liquid and the lower surface of the cover plate 2. Therefore, the bubbles are located in the gap 100. The immersion liquid usually adopts an insulating liquid containing fluorocarbon compounds, and the dielectric strength ≥ 40 kV / 2.5 mm. The surface tension of the immersion liquid usually does not exceed the surface tension of water (i.e., < 72 mN / m).

[0027] The cover plate 2 is covered on the top of the housing 1 and encloses a closed space with the housing 1. A gas hole 201 is horizontally opened on the lower surface of the cover plate 2, and the gas hole 201 is flush with the liquid surface of the immersion liquid; a recovery port 101 is horizontally opened at the top of the side wall of the housing 1, the recovery port 101 is flush with the liquid surface of the immersion liquid and is aligned with the gas hole 201, and both the recovery port 101 and the gas hole 201 are communicated with the gap 100.

[0028] The liquid cooling pipe 3 is hung below the cover plate 2 and is located below the liquid 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, and the ethylene glycol pure aqueous solution has a larger specific heat capacity and can absorb more heat, which helps to carry out heat exchange cooling.

[0029] When the above technical solution is adopted, a number of batteries will be arranged in a matrix and loaded in the shell 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 heat absorption of the immersion liquid will reduce its density, so the high-temperature immersion liquid at the bottom will rise to the top, while the low-temperature immersion liquid 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 in contact with the liquid cooling tube 3 located at the top of the battery, thereby realizing convection circulation inside the immersion liquid. During the convection circulation process, although the tension of the immersion liquid is smaller than that of water, it is still difficult to avoid the generation of bubbles; the aggregation of a large number of tiny bubbles will reduce the contact area between the immersion liquid and the liquid cooling tube, and at the same time increase the internal pressure of the battery pack; and because the tension is smaller, the bubbles generated are more numerous and finer, and therefore more difficult to eliminate; based on this problem, the method adopted in this scheme is to blow air onto the liquid surface of the immersion liquid through the air hole 201 and push the bubbles to move toward the recovery port 101, and by blowing the purge bubbles into the recovery port 101, the bubbles on the liquid surface of the immersion liquid are removed as much as possible.

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

[0031] A liquid inlet 102 is provided at the bottom of the housing 1 .

[0032] The gas delivery mechanism 4 is disposed outside the housing 1. The gas delivery mechanism 4 is connected to the air hole 201, and the gas delivery mechanism 4 delivers air flow to the air hole 201. The gas delivery mechanism 4 can be a small air pump.

[0033] The liquid storage tank 5 is arranged outside the shell 1 and stores immersion liquid. Since the function of the liquid storage tank 5 is to temporarily store the immersion liquid so that a small amount of recovered immersion liquid can flow back into the shell 1, the liquid storage tank 5 usually adopts a small tank body and does not need to occupy a large space of the energy storage battery pack. The two ends of the liquid storage tank 5 are respectively connected to the recovery port 101 and the liquid inlet 102, and a one-way valve is respectively arranged between the liquid storage tank 5 and the recovery port 101 and between the liquid storage tank 5 and the liquid inlet 102, so that the immersion liquid can flow unidirectionally from the recovery port 101 to the liquid storage tank 5, and the immersion liquid can flow unidirectionally from the liquid storage tank 5 to the liquid inlet 102.

[0034] 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 housing 1 .

[0035] When the above technical solution is adopted, the air hole 201 blows the bubbles into the recovery port 101, so that the bubbles enter the liquid storage tank 5 along with a small amount of immersion liquid through the recovery port 101 for recovery. After the bubbles are naturally defoamed in the liquid storage tank 5, they can be pumped back into the shell 1 through the delivery pump 6 to avoid the total amount of immersion liquid in the shell 1 from reducing and causing pressure changes in the battery pack.

[0036] In Figure 3 In a preferred embodiment shown, a plurality of air holes 201 are arranged horizontally and linearly, so as to effectively blow the bubbles on the entire liquid surface. According to Bernoulli's equation, the gas flow velocity can be calculated, that is, the gas flow velocity v = √(2ΔP / ρ). Assuming that the thrust ΔP required to blow the bubbles to move in an open environment is 0.1 MPa and the air density ρ ≈ 1.2 kg / m 3 , it can be calculated that v ≈ 129 m / s. It can be foreseen that in the battery pack design, the required value of the air flow velocity for blowing the bubbles to move will be much smaller than this theoretical value. For example, the required air flow velocity may only be 0.1 - 0.5 m / s. Therefore, it is necessary to limit the aperture of the air holes 201 to limit the air flow for blowing the bubbles. Then, according to the actual effective flow velocity correction formula Q = n·A·v eff , assuming that the flow velocity Q of the bubbles moving with the immersion liquid is 10 L / min, assuming the required flow velocity v eff ≈ 0.85 m / s of the air holes 201, and assuming the number of holes n of the air holes 201 is 50, the radial cross-section A of the air holes 201 can be calculated, and then the aperture of the air holes 201 is approximately 1.0 mm. Therefore, it is reasonable to limit the aperture D of the air holes 201 to 0.5 - 1.0 mm in this solution; at the same time, the arrangement spacing S of the plurality of air holes 201 can satisfy the empirical formula S ≤ 2√(v·t·D), where t is the bubble detachment time and is assumed to be about 0.1 s. Then, the spacing S between adjacent air holes 201 can be known to be S ≤ 7.8 mm, and the limited range in this solution is 5 - 8 mm, which is reasonable.

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

[0038] In Figure 3 In a preferred embodiment shown, it further includes a pressure sensor 7. The pressure sensor 7 is arranged on the lower surface of the cover plate 2 and is located in the gap 100; the pressure change in the gap 100 is detected in real time through the pressure sensor 7 to indirectly monitor the aggregation of bubbles in the gap 100, so as to control the opening and closing of the gas transmission mechanism 4.

[0039] In Figure 4In a preferred embodiment shown, in addition to the air flow through the air holes 201 blowing the bubbles to flow towards the recovery port 101, the recovery port 101 also needs to have a certain negative pressure suction force to fully suck the bubbles and a small amount of immersion liquid into the liquid storage tank 5. Therefore, a cavity 501 is formed above the liquid level of the immersion liquid stored in the liquid storage tank 5. A delivery pipe 8 is connected between the top of the liquid storage tank 5 and the recovery port 101, and the end of the delivery pipe 8 passes through the liquid storage tank 5 and is inserted into the cavity 501; an exhaust port 502 is provided on the side of the top of the liquid storage tank 5, and the exhaust port 502 is connected to the cavity 501. An air extraction mechanism 9 is connected to the exhaust port 502. The air extraction mechanism 9 extracts air outwards through the exhaust port 502 and makes the inside of the cavity 501 in a negative pressure state. The negative pressure state of the cavity 501 forces the recovery port 101 to generate suction to suck away the bubbles and a small amount of immersion liquid. At the same time, the immersion liquid in the liquid storage tank 5 is pumped back to the housing 1 through its bottom outlet, thus avoiding the bubbles that may still remain on the liquid surface in the liquid storage tank 5 from returning to the housing 1 without natural defoaming.

[0040] In Figure 2 a preferred embodiment shown, the lower surface of the cover plate 2 is provided as an inclined surface 202. The distance between the end of the inclined surface 202 close to the recovery port 101 and the immersion liquid level is greater than the distance between the end of the inclined surface 202 far from the recovery port 101 and the immersion liquid level. The inclined surface 202 makes the gap 100 form a triangle with a smaller upper part and a larger lower part, and the recovery port 101 is close to the top of the gap 100. Therefore, it can make the immersion liquid fill the housing 1 as much as possible and reduce the area of the immersion liquid surface, so that the bubbles can gather and help to fully blow away the bubbles; at the same time, it also reduces the space volume of the gap 100 as much as possible, improves the filling ratio of the immersion liquid and reduces the influence of the pressure change in the gap on the battery pack.

[0041] In Figure 3 a preferred embodiment shown, the inclination angle of the inclined surface 202 relative to the horizontal plane is not greater than 5 degrees. The inclination of the inclined surface 202 should not be too large, otherwise it will greatly compress the internal volume of the battery pack and also increase the overall thickness of the battery pack.

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

[0043] As Figure 1 shown, in combination with Figure 2 , a method for using an immersion type energy storage battery pack of the present invention, using an immersion type energy storage battery pack of any of the above embodiments, includes the following steps:

[0044] Step 1: Load the battery into the housing 1 and immerse the battery in the immersion liquid. The heat generated by the battery causes bubbles to form in the immersion liquid and rise to the liquid surface of the immersion liquid. The gap 100 is filled with bubbles. At this time, the pressure sensor 7 detects an increase in pressure in the gap 100, and the air delivery mechanism 4 and the air extraction mechanism 9 are started.

[0045] Step 2: The air delivery mechanism 4 blows air towards the liquid surface through the air holes 201 and makes the bubbles flow towards the recovery port 101; the air extraction mechanism 9 creates a negative pressure environment in the cavity 501 and sucks the bubbles at the recovery port 101.

[0046] Step 3: When the pressure sensor 7 detects a decrease in pressure in the gap 100, the air delivery mechanism 4 and the air extraction mechanism 9 are turned off.

[0047] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An immersion energy storage battery pack, characterized in that: include: A shell (1) having an open top and an interior filled with an immersion liquid; A cover plate (2), which is arranged on the top of the shell (1) and forms a closed space with the shell (1); A liquid cooling pipe (3) is hung below the cover plate (2) and is located below the liquid surface of the immersion liquid; Wherein, a gap (100) is left between the liquid surface of the immersion liquid and the lower surface of the cover plate (2); The lower surface of the cover plate (2) is provided with a horizontal air hole (201), and the air hole (201) is flush with the liquid surface of the immersion liquid; A recovery port (101) is horizontally opened at the top of the side wall of the shell (1), the recovery port (101) is flush with the liquid surface of the immersion liquid and aligned with the air hole (201), and the air hole (201) and the recovery port (101) are both connected to the gap (100); The air holes (201) blow air toward the bubbles floating on the surface of the immersion liquid, and push the bubbles to move toward the recovery port (101).

2. The submerged energy storage battery pack according to claim 1, characterized in that: Also includes: A gas delivery mechanism (4) is arranged outside the housing (1); A liquid storage tank (5), arranged outside the housing (1) and storing immersion liquid; Delivery pump (6); Wherein, a liquid inlet (102) is provided at the bottom of the shell (1); The gas delivery mechanism (4) is in communication with the air hole (201), and the gas delivery mechanism (4) delivers air flow to the air hole (201); The two ends of the liquid storage tank (5) are respectively connected to the recovery port (101) and the liquid inlet (102); one-way valves are respectively provided between the liquid storage tank (5) and the recovery port (101) and between the liquid storage tank (5) and the liquid inlet (102), so that the immersion liquid can flow from the recovery port (101) to the liquid storage tank (5) in one direction, and the immersion liquid can flow 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 housing (1).

3. The submerged energy storage battery pack according to claim 2, characterized in that: The plurality of air holes (201) are arranged horizontally and linearly, the aperture of the air holes (201) is 0.5-1.0 mm, and the spacing between adjacent air holes (201) is 5-8 mm.

4. The submerged energy storage battery pack according to claim 3, characterized in that: 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.

5. The submerged energy storage battery pack according to claim 2, characterized in that: Also includes: A pressure sensor (7) is arranged on the lower surface of the cover plate (2) and is located in the gap (100); The pressure sensor (7) is used to detect pressure changes in the gap (100).

6. The submerged energy storage battery pack according to claim 2, characterized in that: A cavity (501) is formed above the liquid level of the immersion liquid stored in the liquid storage tank (5), a delivery pipe (8) is connected between the top of the liquid storage tank (5) and the recovery port (101), and an end of the delivery pipe (8) passes through the liquid storage tank (5) and is inserted into the cavity (501); An exhaust port (502) is provided on the side of the top of the liquid storage tank (5), the exhaust port (502) is in communication with the cavity (501), and an exhaust mechanism (9) is connected to the exhaust port (502), the exhaust mechanism (9) exhausts air outwards through the exhaust port (502) to form a negative pressure state inside the cavity (501).

7. An immersion energy storage battery pack according to any one of claims 1 to 6, characterized in that: The lower surface of the cover plate (2) is arranged as an inclined surface (202), and the distance between the end of the inclined surface (202) close to the recovery port (101) and the surface of the immersion liquid is greater than the distance between the end of the inclined surface (202) far from the recovery port (101) and the surface of the immersion liquid.

8. The submerged energy storage battery pack according to claim 7, characterized in that: The inclination angle of the inclined surface (202) relative to the horizontal plane is not greater than 5 degrees.

9. The submerged energy storage battery pack according to claim 7, characterized in that: Both ends of the inclined surface (202) extend along the length direction of the shell (1).

10. A method for using an immersion energy storage battery pack, characterized in that: Using the submerged energy storage battery pack described in claim 6, The following steps are included: Step 1: A battery is loaded into the housing (1) and immersed in the immersion liquid. The battery generates heat to form bubbles in the immersion liquid and the bubbles float to the liquid surface of the immersion liquid. The gap (100) is filled with bubbles. At this time, the pressure sensor (7) detects that the pressure in the gap (100) increases, and the gas supply mechanism (4) and the gas extraction mechanism (9) are activated. Step 2: the gas delivery mechanism (4) blows gas toward the liquid surface through the air hole (201) and causes the bubbles to flow toward the recovery port (101); the gas extraction mechanism (9) creates a negative pressure environment in the cavity (501) and causes the recovery port (101) to extract the bubbles; Step three, detecting through the pressure sensor (7) that the pressure in the gap (100) is reduced, and closing the gas supply mechanism (4) and the gas extraction mechanism (9).

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