Immersed battery liquid cooling device and energy storage battery pack

Abstract

The invention provides an immersed battery liquid cooling device and an energy storage battery pack, and belongs to the field of battery liquid cooling, the immersed battery liquid cooling device comprises a heat exchange tube, the heat exchange tube is arranged in a shell and located at the top of a battery, and the heat exchange tube is immersed below the liquid level of a heat-conducting medium; the infusion tube is arranged in the shell and located at the bottom of the battery, and through holes are distributed in the infusion tube. The circulating pump pumps the heat-conducting medium; a backflow opening is formed in the position, close to the liquid level of the heat-conducting medium, of the side wall of the shell and communicates with the liquid conveying pipe through a circulating pump, and the heat-conducting medium at the bottom of the shell is sucked through the through hole and then conveyed to the top of the shell through the backflow opening through the circulating pump. The immersion liquid flows through gaps of batteries from top to bottom to form cooling runners, the low-temperature immersion liquid continuously exchanges heat with a battery pack heating in the charging and discharging process, the heat-carrying high-temperature immersion liquid is conveyed by the circulating pump to flow back to the top of the box body again, the heat exchange pipe cools the backflow immersion liquid, and the process is repeated. And the low-temperature immersion liquid can uniformly and quickly flow through the surface of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of battery liquid cooling, and particularly to an immersion battery liquid cooling device and an energy storage battery pack. Background Art

[0002] In recent years, with the rapid development of electrochemical energy storage technology, the immersion liquid cooling energy storage system has gradually become the mainstream design solution for large-capacity battery packs due to its high-efficiency heat dissipation ability and intrinsic safety. For example, in Tesla Patent US20210083221A1, a thermal cycle of upward and downward convection of the immersion liquid is formed due to 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 between the high-temperature immersion liquid and the liquid cooling plate, the temperature drops, and then it descends back to the bottom again.

[0003] Currently, relying on the natural convection cooling method of the immersion coolant to cool the battery has limited cooling effect. The reason is that when the battery undergoes high-rate charge and discharge, a large amount of heat is generated. The position where the high-temperature immersion liquid rises and exchanges heat with the descending low-temperature immersion liquid is in the middle of the battery, resulting in a serious loss of the cooling capacity of the low-temperature immersion liquid when it descends to the bottom of the battery, and further leading to a large temperature difference between the top and bottom of the battery, which affects the use of the battery. Summary of the Invention

[0004] In view of this, the present invention provides an immersion battery liquid cooling device and an energy storage battery pack to solve the problem of poor cooling effect of currently relying on the natural convection cooling method of the immersion coolant to cool the battery.

[0005] The technical solution of the present invention is realized as follows: The present invention provides an immersion battery liquid cooling device, which is arranged in the housing of the battery pack. A number of batteries are arranged in the housing and filled with a heat-conducting medium to immerse the batteries. The device includes a heat exchange tube, which is arranged in the housing and located at the top of the batteries, and the heat exchange tube is immersed below the liquid level of the heat-conducting medium; an infusion tube, which is arranged in the housing and located at the bottom of the batteries, and through holes are arranged on the infusion tube; a circulation pump, which is used to pump the heat-conducting medium; wherein, a return port is arranged at a position on the side wall of the housing close to the liquid level of the heat-conducting medium, and the return port is connected to the infusion tube through the circulation pump. The heat-conducting medium at the bottom of the housing is sucked through the through holes by the circulation pump and then conveyed to the top of the housing through the return port.

[0006] On the basis of the above technical solution, preferably, it further includes a liquid storage tank, which is connected to the output end and the input end of the heat exchange tube, and cooling water is stored in the liquid storage tank; a delivery pump, which is connected between the liquid storage tank and the input end of the heat exchange tube, and the delivery pump pumps cooling water to the heat exchange tube; wherein, the temperature difference between the battery surface and the heat-conducting medium is adjusted by adjusting the total delivery volume of the delivery pump per unit time.

[0007] More preferably, a gap is left between adjacent batteries; a plurality of through holes arranged on each infusion tube are in a column, or a plurality of through holes corresponding to each other on each infusion tube are in a column, and each column of through holes is aligned with the gap.

[0008] More preferably, the calculation formula for the total amount of delivery of the delivery pump per unit time is

[0009] q a =Q(A△T) -1 ×(ρul) -1 / 2 ×μ -1 / 6 ×c p 1 / 3 ×λ -2 / 3 ×A0×n×k -1 ,

[0010] wherein, Q is the heat generated during the charge and discharge process of the battery, A is the contact area between the battery and the heat-conducting medium, △T is the temperature difference between the battery surface and the heat-conducting medium, ρ is the density of the heat-conducting medium, l is the height of the battery, u is the flow velocity of the heat-conducting medium in the gap, μ is the viscosity of the heat-conducting medium, c p is the specific heat capacity of the heat-conducting medium, λ is the thermal conductivity of the heat-conducting medium, A0 is the horizontal cross-sectional area of the gap, n is the number of columns of through holes, and k is an empirical constant.

[0011] More preferably, the flow velocity of the heat-conducting medium in each gap is adjusted by adjusting the pumping flow velocity of the circulation pump.

[0012] More preferably, the infusion tube includes a plurality of branch tubes, which are respectively arranged in each gap, and a plurality of through holes are arranged on the branch tubes; a main tube, which is simultaneously connected to one end of a plurality of branch tubes, one end of the main tube passes through the housing and extends to the external environment, and the outer end of the main tube is connected to the return port through a circulation pump.

[0013] More preferably, the distance between adjacent through holes in each column is 3-5 cm.

[0014] More preferably, the width of the gap is not greater than 10 cm.

[0015] Based on the above technical solutions, preferably, the aperture of the through hole is 1-2 cm.

[0016] On the other hand, the present invention also provides an energy storage battery pack, which includes the above-mentioned immersion battery liquid cooling device, and further includes a housing and a plurality of batteries arranged in the housing.

[0017] The immersion battery liquid cooling device and the energy storage battery pack of the present invention have the following

[0018] Beneficial effects:

[0019] (1) In the present invention, the immersion coolant inside the box body is driven by a circulation pump, so that the immersion liquid flows through the gaps between the batteries from top to bottom to form a cooling channel. The low-temperature immersion liquid continuously exchanges heat with the battery pack generating heat during the charge and discharge process and takes away the heat of the battery. The high-temperature immersion liquid carrying heat is transported back to the top of the box body by the circulation pump, and the heat exchange tube cools the returned immersion liquid and repeats the above process, enabling the low-temperature immersion liquid to flow through the battery surface evenly and quickly, and avoiding weakening the cooling effect due to the heat exchange position being in the middle of the battery.

[0020] (2) The present invention adjusts the temperature difference between the battery surface and the heat-conducting medium by adjusting the total amount of liquid transported by the delivery pump per unit time, thereby controlling the flow rate of the heat-conducting medium in the gap, and can accurately adjust the cooling rate according to the design requirements, which helps to improve the cooling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 is a perspective view of the immersion battery liquid cooling device of the present invention;

[0023] Figure 2 is a schematic side-sectional structure view of the immersion battery liquid cooling device of the present invention;

[0024] Figure 3 is a perspective view of the infusion tube of the present invention.

[0025] In the figure: 1. Housing; 11. Return port; 62. Battery; 201. Gap; 3. Heat exchange tube; 4. Infusion tube; 41. Branch pipe; 42. Main pipe; 401. Through hole; 5. Circulation pump; 6. Liquid storage tank; 7. Delivery pump. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] As Figure 1 shown, in combination with Figure 2 , an immersion battery liquid cooling device of the present invention includes a heat exchange tube 3, an infusion tube 4, and a circulation pump 5.

[0028] Among them, the immersion battery liquid cooling device is arranged in the housing 1 of the battery pack. A plurality of batteries 2 are arranged in the housing 1 and filled with a heat-conducting medium to immerse the batteries 2. A return port 11 is arranged at a position on the side wall of the housing 1 close to the liquid level of the heat-conducting medium. The heat-conducting medium is a hydrocarbon oil-based insulating liquid or a fluorohydrocarbon oil-based insulating liquid.

[0029] The heat exchange tube 3 is arranged in the housing 1 and located above the battery 2. The heat exchange tube 3 is immersed below the liquid level of the heat-conducting medium. A coolant flows through the heat exchange tube 3, and water cooling or oil cooling can be adopted. The heat exchange tube 3 adopts a coil structure.

[0030] The liquid delivery pipe 4 is arranged in the housing 1 and located at the bottom of the battery 2. Through holes 401 are arranged on the liquid delivery pipe 4.

[0031] The circulation pump 5 is used to pump the heat-conducting medium; the return port 11 is connected to the liquid delivery pipe 4 through the circulation pump 5. The heat-conducting medium at the bottom of the housing 1 is sucked through the through holes 401 by the circulation pump 5 and then transported to the top of the housing 1 through the return port 11.

[0032] When the above technical solution is adopted, the heat-conducting medium in the housing 1 flows by the driving of the circulation pump 5 arranged outside the housing 1. The circulation pump 5 sucks the heat-conducting medium in the housing 1 through the liquid delivery pipe 4, so that the heat-conducting medium above the housing 1 cooled by the heat exchange tube 3 flows through the gaps 201 between adjacent batteries from top to bottom. Since the heat-conducting medium that has completed heat exchange below the housing 1 has been sucked away by the circulation pump 5, the low-temperature heat-conducting medium flowing from top to bottom forms a cooling flow path in the gap 201. When the heat-conducting medium flows in the gap 201, it exchanges heat with the battery 2 that generates heat during the charge and discharge process and takes away the heat of the battery 2; the heat-conducting medium below the housing 1 enters the liquid delivery pipe 4 through the through holes 401 on the upper surface of the liquid delivery pipe 4 at the bottom of the battery 1, so as to lead out the high-temperature heat-conducting medium outside the housing 1. Through the transportation of the circulation pump 5 and via the return port 11, the heat-conducting medium after heat exchange is re-transported to the heat exchange tube 3 arranged at the top of the housing 1, and the heat exchange tube 3 cools the returned heat-conducting medium. During the heat exchange process, the high-temperature heat-conducting medium after heat exchange is led out of the housing 1, and the low-temperature heat-conducting medium continuously flows in the flow path of the gap 201. Therefore, the heat exchange area between the high-temperature heat-conducting medium and the low-temperature heat-conducting medium will not be located in the middle of the battery 2, and thus the problem that the heat exchange capacity of the low-temperature heat-conducting medium is severely weakened when it flows to the bottom of the battery 2 will not occur, which ensures that the low-temperature heat-conducting medium has a good and continuous heat exchange and cooling effect.

[0033] In Figure 2 In a preferred embodiment shown, a liquid storage tank 6 and a delivery pump 7 are further included.

[0034] Among them, the liquid storage tank 6 is connected to the output end and the input end of the heat exchange tube 3, and cooling water is stored in the liquid storage tank 6.

[0035] The delivery pump 7 is a water pump, which is connected between the liquid storage tank 6 and the input end of the heat exchange tube 3. The delivery pump 7 pumps cooling water to the heat exchange tube 3. In order to effectively cool the battery 2, it is necessary to ensure that the heat-conducting medium has a high flow rate in the gap 201. However, the flow rate is difficult to accurately measure. Therefore, in actual operation of this embodiment, the temperature difference between the surface of the battery 2 and the heat-conducting medium is adjusted by adjusting the total delivery volume of the delivery pump 7 per unit time. The greater the total delivery volume of the delivery pump 7 per unit time, the faster the flow rate of the heat-conducting medium in the gap 201, and the better the cooling effect.

[0036] In Figure 2 In a preferred embodiment shown, a gap 201 is left between adjacent batteries 2; several through holes 401 arranged on each infusion tube 4 are in a column, or several through holes 401 at corresponding positions on each infusion tube 4 are in a column, and each column of through holes 401 is aligned with the gap 201, so that the heat-conducting medium will not be hindered when entering the through holes 401 and the flow rate of the heat-conducting medium will not be reduced.

[0037] In Figure 2 In a preferred embodiment shown, the calculation formula for the total delivery volume of the delivery pump 7 per unit time is

[0038] q a =Q(A△T) -1 ×(ρul) -1 / 2 ×μ -1 / 6 ×c p 1 / 3 ×λ -2 / 3 ×A0×n×k -1 , (1)

[0039] Wherein, Q is the heat generation amount during the charge and discharge process of the battery 2, A is the contact area between the battery 2 and the heat-conducting medium, △T is the temperature difference between the surface of the battery 2 and the heat-conducting medium, ρ is the density of the heat-conducting medium, l is the height of the battery 2, u is the flow rate of the heat-conducting medium in the gap 201, μ is the viscosity of the heat-conducting medium, c p is the specific heat capacity of the heat-conducting medium, λ is the thermal conductivity of the heat-conducting medium, A0 is the horizontal cross-sectional area of the gap 201, n is the number of columns of the through holes 401, and k is an empirical constant.

[0040] The derivation process of the above calculation formula is as follows: Determine the flow rate of the heat-conducting medium in the gap 201 of each battery 1 according to the heat generation amount of the battery 1, and then the total flow rate of the delivery pump 7 can be obtained according to the flow rates of the heat-conducting media.

[0041] First, calculate the required convective heat transfer coefficient according to the heat generation amount during the charge and discharge process of the battery

[0042] h=Q(A△T) -1, (2)

[0043] Then, according to the obtained convective heat transfer coefficient h, determine the flow velocity u of the gap flow channel of each battery pack. Equation (2) can be transformed into

[0044] h = (ρul) -1 / 2 ×μ -1 / 6 ×c p 1 / 3 ×λ -2 / 3 ×k -1 , (3)

[0045] Furthermore, the flow velocity u is obtained through conversion by Equation (3). Among them, k is the empirical relationship coefficient of the experimental relationship of the external flat plate of the liquid, and usually takes the value of 0.664.

[0046] Again, according to the obtained flow velocity, combine the following Equation (4) to determine the flow rate of the heat-conducting medium in the gap 201 of battery 1

[0047] q = μ×A0, (4)

[0048] Finally, since the total flow rate of the delivery pump 7 is the sum of the flow rates of the heat-conducting medium in all the gaps 201, Equation (1) is obtained by combining Equations (2) to (4).

[0049] In Figure 2 In a preferred embodiment shown, the flow velocity of the heat-conducting medium in each gap 201 is adjusted by adjusting the pumping flow velocity of the circulation pump 5, because the pumping flow velocity of the circulation pump 5 essentially determines the flow velocity of the heat-conducting medium in the gap 201.

[0050] In Figure 3 In a preferred embodiment shown, the infusion tube 4 includes a branch pipe 41 and a main pipe 42.

[0051] Among them, a number of branch pipes 41 are arranged in each gap 201 in one-to-one correspondence, and a number of through holes 401 are arranged on the branch pipe 41. A sunken groove can be opened on the ground of the box body 1, and the branch pipe 41 is arranged in the sunken groove. The diameter of the branch pipe 41 is usually 3 - 5 cm and needs to be designed according to the requirements of the battery pack.

[0052] The main pipe 42 is simultaneously connected to one end of a number of branch pipes 41. One end of the main pipe 42 passes through the housing 1 and extends to the external environment. The outer end of the main pipe 42 is connected to the return port 11 through the circulation pump 5. The diameter of the main pipe 42 is 5 - 10 cm. The function of the main pipe 42 is to converge a number of branch pipes 41. An outlet can be arranged at the bottom of the side of the box body 1. The output end of the main pipe 42 is connected to the outlet, and the outlet is connected to the circulation pump 7.

[0053] In Figure 2In a preferred embodiment shown, the distance between adjacent through holes 401 in each column is 3 - 5 cm. The distance between the through holes 401 does not have a great impact on the flow rate of the heat-conducting medium in the gap 201. The reason is that the flow rate of the heat-conducting medium in the gap 201 is substantially mainly determined by the pumping flow rate of the circulation pump 5. However, if the distance between the through holes 401 is too large, it will affect the distance between the liquid flows formed by the heat-conducting medium, and thus affect the contact area between the heat-conducting medium and the surface of the battery 2.

[0054] In Figure 2 In a preferred embodiment shown, the width of the gap 201 is not greater than 10 cm. If the width of the gap 201 is too large, it will be difficult for the liquid flow formed by the heat-conducting medium to form effective contact with the surface of the battery 2, thus affecting the heat exchange effect, and it will also lead to a reduction in the number of batteries 2 arranged in the box body 1, affecting the energy storage performance; if the width of the gap 201 is too small, it will reduce the cross-sectional area of the flow channel, resulting in an extended contact residence time of the oily heat-conducting medium liquid flow with the surface of the battery 2, and thus affecting the flow rate of the heat-conducting medium.

[0055] In Figure 2 In a preferred embodiment shown, the aperture of the through hole 401 is 1 - 2 cm. If the aperture of the through hole 401 is too small, it will hinder the heat-conducting medium from entering the through hole 401, thus having an adverse impact on the flow rate of the heat-conducting medium; the aperture of the through hole 401 can be larger, but it should not be greater than the width of the gap 201.

[0056] As Figure 1 shown, in combination with Figure 2 , a kind of energy storage battery pack of the present invention includes the immersion type battery liquid cooling device of any one of the above embodiments, and also includes a housing 1 and a plurality of batteries 2 arranged in the housing 1.

[0057] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An immersion battery liquid cooling device is arranged inside the housing (1) of a battery pack. A number of batteries (2) are arranged inside the housing (1) and the batteries (2) are filled with a heat-conducting medium in an immersed manner. It is characterized in that, Comprising: A heat exchange tube (3), disposed inside the housing (1) and on top of the battery (2), and the heat exchange tube (3) is immersed below the liquid level of the heat-conducting medium; An infusion tube (4), disposed inside the housing (1) and at the bottom of the battery (2), and through holes (401) are arranged on the infusion tube (4); A circulation pump (5) for pumping the heat-conducting medium; Wherein, a return port (11) is provided at a position on the side wall of the housing (1) close to the liquid level of the heat-conducting medium, and the return port (11) is connected to the infusion tube (4) through the circulation pump (5), and the heat-conducting medium at the bottom of the housing (1) is sucked through the through holes (401) by the circulation pump (5) and then transported to the top of the housing (1) through the return port (11).

2. The immersion battery liquid cooling device according to claim 1, wherein Further comprising: A liquid storage tank (6), connected to the output end and the input end of the heat exchange tube (3), and cooling water is stored in the liquid storage tank (6); A delivery pump (7), connected between the liquid storage tank (6) and the input end of the heat exchange tube (3), and the delivery pump (7) pumps cooling water to the heat exchange tube (3); Wherein, the temperature difference between the surface of the battery (2) and the heat-conducting medium is adjusted by adjusting the total delivery amount of the delivery pump (7) per unit time.

3. The immersion battery liquid cooling device according to claim 2, wherein: A gap (201) is left between adjacent batteries (2); several through holes (401) arranged on each infusion tube (4) form a column, or several through holes (401) at corresponding positions on each infusion tube (4) form a column, and each column of the through holes (401) is arranged to align with the gap (201).

4. The immersion battery liquid cooling device according to claim 3, wherein: The calculation formula for the total delivery amount of the delivery pump (7) per unit time is q a = Q(A△T) -1 ×(ρul) -1 / 2 ×μ -1 / 6 ×c p 1 / 3 ×λ -2 / 3 ×A0×n×k -1 , Among them, Q is the heat generation during the charge and discharge process of the battery (2), A is the contact area between the battery (2) and the heat-conducting medium, ΔT is the temperature difference between the surface of the battery (2) and the heat-conducting medium, ρ is the density of the heat-conducting medium, l is the height of the battery (2), u is the flow velocity of the heat-conducting medium in the gap (201), μ is the viscosity of the heat-conducting medium, c p is the specific heat capacity of the heat-conducting medium, λ is the thermal conductivity of the heat-conducting medium, A0 is the horizontal cross-sectional area of the gap (201), n is the number of columns of the through holes (401), and k is an empirical constant.

5. The immersion type battery liquid cooling device according to claim 4, wherein: The flow rate of the heat-conducting medium in each gap (201) is adjusted by adjusting the pumping flow rate of the circulation pump (5).

6. The immersion battery liquid cooling device according to claim 3, wherein: The infusion tube (4) includes Several branch tubes (41), respectively arranged in each gap (201), and several through holes (401) are arranged on the branch tubes (41); A main tube (42), simultaneously connected to one end of several branch tubes (41), one end of the main tube (42) extends through the housing (1) to the external environment, and the outer end of the main tube (42) is connected to the return port (11) through the circulation pump (5).

7. The immersion type battery liquid cooling device according to claim 6, characterized in that: The distance between adjacent through holes (401) in each column is 3 - 5 cm.

8. The immersion battery liquid cooling device according to claim 3, wherein: The width of the gap (201) is not greater than 10 cm.

9. The immersion type battery liquid cooling device according to claim 1, wherein: The aperture of the through hole (401) is 1 - 2 cm.

10. A energy storage battery pack, characterized in that: Comprising the immersion type battery liquid cooling device according to any one of claims 1 to 9, further comprising a housing (1) and several batteries (2) arranged inside the housing (1).

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