Portable power battery pack heat dissipation device

Abstract

The application discloses a portable power battery pack heat dissipation device. The battery pack shell in the application is uniformly and equidistantly arranged with power batteries, the power batteries are uniformly and equidistantly arranged with evaporation pipes, the gap between the batteries and the evaporation pipes is filled with (solid-liquid) phase change material, the evaporation pipes are filled with appropriate (liquid-gas) phase change material, the battery pack shell is arranged with a condensing plate, the outer wall surface of the condensing plate is arranged with dense heat dissipation fins, the heat dissipation fins are arranged with a transparent cover plate outside, and the upper end and the left and right sides of the cover plate are arranged with louvers. The "V"-shaped condensing surface in the application is helpful for the middle area to first liquefy and release heat, the two sides are second, and the liquefied liquid phase can be secondarily distributed, so that more liquefied liquid phase phase change working medium enters the evaporation pipe in the middle part, thereby entering the next cycle. The inverted "V"-shaped backflow wall surface is helpful for accelerating the liquid phase phase change working medium to enter the evaporation pipe again.

Description

Technical Field

[0001] This invention belongs to the field of heat dissipation of power lithium battery packs, and relates to a highly efficient composite heat dissipation method that integrates solid-liquid phase change cooling, liquid-gas phase change cooling and fin heat dissipation. It is particularly suitable for the heat dissipation requirements of power lithium battery packs under high-rate charging and discharging conditions. Background Technology

[0002] Lithium metal, hailed as the "green energy metal" and "white oil" that will change the world in the 21st century, is primarily used in lithium-ion battery manufacturing. Lithium-ion batteries are favored for their high energy density, light weight, low self-discharge rate, and environmental friendliness. From small items like electronic watches, CD players, mobile phones, MP3 players, MP4 players, cameras, camcorders, remote controls, shavers, hand drills, and children's toys, to large-scale applications such as emergency power supplies in hospitals, hotels, supermarkets, and telephone exchanges, lithium-ion batteries are widely used in power tools. However, lithium-ion batteries are particularly sensitive to temperature. High temperatures reduce their capacity and cause internal temperature instability, further increasing the risk of internal short circuits and damage to nearby components, potentially leading to thermal runaway accidents. In real-world applications, lithium-ion battery packs inevitably operate under harsh conditions of high-rate charging and discharging. In such situations, the large current generates significant Joule heat due to the Ohm effect, causing the battery pack temperature to rise. Therefore, addressing the overheating problem is of paramount importance.

[0003] Currently, there are two main methods for heat dissipation of lithium battery packs under high-rate charge and discharge conditions: The first is to optimize the battery pack structure. By optimizing the arrangement and spacing of the battery cells, the effect of localized heat accumulation can be reduced. The second is to add auxiliary heat dissipation devices to improve heat transfer efficiency, enabling the heat from the battery itself to be quickly transferred to other media or the external environment, thereby reducing the battery temperature, eliminating the safety hazard of thermal runaway, and extending the battery pack's lifespan.

[0004] Common heat dissipation methods include air cooling, liquid cooling, phase change material (PCM) cooling, and heat pipe cooling. Air cooling utilizes airflow over the battery surface to create convection heat transfer, transferring heat generated by the battery to the air and carrying it away. However, as lithium-ion battery packs continue to develop towards greater quantity, higher energy, larger mass, and denser packing, air cooling alone is no longer sufficient to meet the heat dissipation requirements. Liquid cooling works similarly to air cooling, except the heat exchange medium is liquid instead of air. Liquid cooling has disadvantages such as numerous pipe joints, leakage risks, and generally higher weight, which limits its development to some extent. Phase change material (PCM) cooling relies on the latent heat of phase change to transfer heat. Due to the low thermal conductivity of PCM materials and the saturation point of phase change heat storage, there is a risk of failure under certain conditions. Therefore, PCM cooling alone cannot be applied to lithium battery pack heat dissipation and needs to be used in combination with other heat dissipation methods. Heat pipe cooling transfers heat through the evaporation and condensation of liquid within a fully enclosed vacuum tube. Heat pipes are heat transfer elements with extremely high thermal conductivity. However, their high cost makes large-scale use impractical. Summary of the Invention

[0005] The purpose of this invention is to address the issue of a portable battery pack that can be used as a power source for a hand drill. During prolonged charging and discharging or high-rate charging and discharging in a short period, a designed composite high-efficiency heat dissipation device is used to maintain the battery pack temperature within a reasonable range, preventing overall or localized overheating. This eliminates safety hazards when the battery pack operates under harsh conditions, indirectly maintaining its charging and discharging performance and extending its lifespan.

[0006] To achieve the above objectives, a high-efficiency composite heat dissipation device integrating (solid-liquid) phase change cooling, (liquid-gas) phase change cooling, and fin heat dissipation is invented.

[0007] The present invention includes a battery pack housing and a condenser plate located above the housing; The battery pack housing contains power batteries arranged at equal intervals, and evaporation tubes are arranged at equal intervals between the power batteries. The gap between the power batteries and the evaporation tubes is filled with solid-liquid phase change material, and the evaporation tubes are filled with liquid-gas phase change material.

[0008] The outer wall of the condenser plate is provided with heat dissipation fins, which are surrounded by a transparent cover plate. The top and left and right sides of the cover plate are provided with louvers.

[0009] The condensing plate has a condensing cavity, and the condensing wall surface in the condensing cavity is generally "V" shaped to increase the contact area of ​​liquefaction and improve the heat dissipation rate; the return wall surface on the lower substrate of the condensing plate is generally inverted "V" shaped to increase the rate at which the liquid phase returns to the evaporation tube and improve the circulation efficiency.

[0010] The beneficial effects of this invention are as follows: In this invention, the heat generated by the battery is transferred to the (solid-liquid) phase change material through thermal conduction. After absorbing heat, the material changes from a solid to a liquid. The heat absorbed by the (solid-liquid) phase change material is then transferred to the side wall of the evaporator tube through thermal conduction. The heat absorbed by the wall is transferred to the (liquid-gas) phase change material, which absorbs heat and changes from a liquid to a gas. The gas carrying heat expands and rises, liquefying and releasing heat when it encounters the condenser plate. The heat from the condenser plate is transferred to the heat dissipation fins. A blower introduces air into the transparent cover, and an exhaust fan draws the air out of the transparent cover. The fins transfer heat to the outside air through forced convection heat exchange with the air inside the transparent cover.

[0011] The "V"-shaped condensation surface of the condenser plate helps the middle area to liquefy and release heat first, followed by the sides. It can also perform secondary distribution of the liquefied liquid phase, allowing more of the liquefied liquid phase change working fluid to enter the evaporator tube in the middle section, thus entering the next cycle. The inverted "V"-shaped reflux wall helps to accelerate the re-entry of the liquid phase change working fluid into the evaporator tube.

[0012] In summary, the liquefied working fluid at the condenser plate wall, under the combined influence of internal pressure, gravity, and temperature difference, helps to reduce the overall temperature and temperature difference, and returns irregularly to the evaporator tube, forming a continuous cooling cycle. This invention is particularly suitable for cooling devices in portable high-power charging and discharging power supplies. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 for Figure 1 Sectional view at point AA; Figure 3 This is a structural diagram of the phase transition space of a (liquid-gas) phase change material; Figure 4 for Figure 3 A magnified view of the condenser wall at point I-I, where blue arrows represent the direction of gas flow and green arrows represent the direction of liquid flow; Figure 5 for Figure 3 A magnified view of the reflux wall of the condenser plate at point II-II, with green arrows indicating the direction of liquid flow during reflux; Figure 6 for Figure 3 A partial enlarged view of the evaporator tube sidewall structure at section III-III; Figure 7 , Figure 8 All Figure 4 A sectional view at point BB, in which Figure 7 It is a single-corrugated structure where the condensation wall surface is corrugated only in the X direction. Figure 8It is a double-corrugated structure with corrugated walls in both the X and Y directions. Detailed Implementation

[0014] The present invention will now be described in detail with reference to the accompanying drawings.

[0015] The main conceptual principle of this invention is as follows: To increase the heat dissipation and contact area per unit area on the outer surface of the condenser plate, and to increase the heat transfer efficiency during convective heat transfer on the outer surface of the condenser plate, heat dissipation fins are densely arranged on the outer surface of the condenser plate. To increase the heat absorption and contact area per unit area on the inner surface of the condenser plate cavity, and to increase the heat transfer efficiency during convective heat transfer on the inner surface of the condenser plate cavity, the inner surface of the condenser plate cavity is designed to be corrugated in the X direction, and can be corrugated or rectangular in the Y direction. To increase the heat dissipation rate of the fins, a blower or induced draft fan is used for forced convection heat transfer. To reduce the temperature difference between the central and peripheral areas of the battery pack and to increase the amount of liquid working fluid returning to the central area of ​​the battery pack, the condenser plate condensation surface is designed as a "V" shape, and to improve the liquid phase return rate, the return wall of the condenser plate is designed as an inverted "V" shape. To increase the heat conduction and contact area per unit area on the evaporator tube surface, and to enhance the heat transfer efficiency during convective heat transfer, the evaporator tube surface is designed as an uneven plane (corrugated, sawtooth, etc. are all acceptable). To facilitate rapid heat dissipation during battery operation, solid-liquid and liquid-gas phase change materials are used for auxiliary heat conduction. Specifically, the gap between the battery and the evaporator tube within the battery pack is filled with solid-liquid phase change material, while the interior of the evaporator tube is filled with liquid-gas phase change material.

[0016] Based on the above concept, the technical solution of the present invention is as follows: power batteries are evenly and equidistantly arranged inside the battery pack shell, evaporation tubes are evenly and equidistantly arranged between the power batteries, the gap between the batteries and the evaporation tubes is filled with (solid-liquid) phase change material, the evaporation tubes are filled with an appropriate amount of (liquid-gas) phase change material, a condenser plate is arranged on the battery pack shell, dense heat dissipation fins are arranged on the outer wall of the condenser plate, a transparent cover plate is arranged outside the heat dissipation fins, and a louver is arranged at the top and on the left and right sides of the cover plate.

[0017] like Figure 1 and Figure 2 As shown, this embodiment includes a transparent cover plate 1, a condenser plate 2, louvers 3, an evaporator tube 4, a (solid-liquid) phase change material 5, a battery pack shell 6, heat dissipation fins 7, a condenser plate cavity 8, a power battery pack 9, and a (liquid-gas) phase change material.

[0018] The detailed parameters and dimensions of the condenser plate, evaporator tube, heat dissipation fins, and battery pack casing can be determined by performing heat dissipation calculations based on the actual rated voltage and capacity of the battery pack.

[0019] In some preferred embodiments, the (solid-liquid) phase change material in the composite heat dissipation device is composed of paraffin wax, expanded graphite, and copper foam. The high thermal conductivity of expanded graphite improves the overall thermal conductivity of the phase change material, while the porous thermally conductive framework of copper foam can encapsulate the expanded graphite, reducing its fluidity during the solid-liquid phase transition and preventing the paraffin wax from accumulating downwards under gravity after changing from a solid to a liquid phase, thus improving the overall heat transfer capacity of the entire system.

[0020] In some preferred embodiments, the working fluid of the (liquid-gas) phase change material in the evaporation tube of the composite heat dissipation device is acetone, carbon nanotube oil-based nanofluid, heat-conducting oil nanofluid, Cu-water nanofluid, Al2O3 nanofluid, etc., which have excellent heat transfer properties.

[0021] In some preferred embodiments, the structure of the evaporator tube of the composite heat dissipation device is not limited to corrugated type, and can be designed as vertical, spiral, sawtooth, etc., see Figure 6 .

[0022] In some preferred embodiments, the condenser plate of the composite heat dissipation device has a V-shaped condensation wall in its condensation cavity, which increases the contact area for liquefaction and improves the heat dissipation rate; the return wall is an inverted V-shape, which increases the rate at which the liquid phase returns to the evaporation tube and improves the circulation efficiency. Figure 3 , Figure 4 and Figure 5 .

[0023] Furthermore, the condensation wall surface of the composite heat dissipation device has a corrugated structure in the X direction, while its structure in the Y direction can be either corrugated or rectangular. The corrugated structure increases the condensation area and improves the heat dissipation rate. (See...) Figure 7 and Figure 8 .

[0024] Furthermore, the lower substrate of the condenser plate of the composite heat dissipation device is also the upper cover plate of the battery pack, and the lower substrate has many through holes, each corresponding to a corresponding evaporator tube. The two are in the same position in the Z direction, so that the upper end of the evaporator tube leads to the cavity of the condenser plate. Therefore, when there is a temperature difference in the XY plane inside the battery pack, the evaporator tube and the condenser cavity will also undergo lateral heat transfer, thereby reducing the temperature difference.

[0025] In some preferred embodiments, the louvers at the upper end of the transparent cover of the composite heat dissipation device can be equipped with miniature blowers, and the louvers on the left and right sides can be equipped with miniature exhaust fans, which transforms the natural convection heat dissipation of the fins into forced convection heat transfer, thereby increasing the heat transfer coefficient and the heat dissipation rate.

[0026] One of the batteries inside the battery pack of the composite heat dissipation device can also serve as the power source for a miniature blower and induced draft fan, maximizing battery utilization.

[0027] The process of performing composite heat dissipation using the device of this embodiment: The heat generated by the battery is transferred to the (solid-liquid) phase change material through thermal conduction. After absorbing heat, the (solid-liquid) phase change material changes from a solid to a liquid. The heat absorbed by the (solid-liquid) phase change material is then transferred to the side wall of the evaporator tube through thermal conduction. The heat absorbed by the wall is transferred to the (liquid-gas) phase change material, which absorbs heat and changes from a liquid to a gas.

[0028] The gas carrying heat expands and rises when heated, liquefying and releasing heat when it encounters the condenser plate. The heat from the condenser plate is transferred to the heat dissipation fins. The blower pushes air into the transparent cover, and the exhaust fan draws the air out of the transparent cover. The fins transfer heat to the outside air through forced convection heat exchange with the air inside the transparent cover.

[0029] The "V"-shaped condensation surface of the condenser plate facilitates the initial liquefaction and heat release in the central area, followed by the sides. It also allows for secondary distribution of the liquefied liquid phase, enabling more of the liquefied phase-change working fluid to enter the evaporator tubes in the central section, thus entering the next cycle. The inverted "V"-shaped reflux wall further accelerates the re-entry of the liquid phase-change working fluid into the evaporator tubes. Under the combined influence of internal pressure, gravity, and temperature difference, the liquefied working fluid at the condenser plate wall tends to return to the evaporator tubes irregularly, reducing the overall temperature and temperature difference, thus forming a continuously circulating heat dissipation process.

Claims

1. A portable power battery pack heat dissipation device, characterized in that: Includes the battery pack casing and the condenser plate located on top of the casing; The battery pack shell contains power batteries arranged at equal intervals, and evaporation tubes are arranged at equal intervals between the power batteries. The gap between the power batteries and the evaporation tubes is filled with solid-liquid phase change material, and the evaporation tubes are filled with liquid-gas phase change material. The outer wall surface of the condenser plate is provided with heat dissipation fins, which are surrounded by a transparent cover plate. The top and left and right sides of the cover plate are provided with louvers. The condenser plate has a condensation cavity, and the condensation wall surface in the condensation cavity is generally "V" shaped, which helps the middle area to liquefy and release heat first, followed by the sides. It can also perform secondary distribution of the liquefied liquid phase, so that more of the liquefied liquid phase change working fluid enters the evaporator tube in the middle part, thus entering the next cycle. The return wall surface on the lower plate of the condenser plate is generally inverted "V" shaped, which is used to increase the rate of liquid phase return to the evaporator tube and improve the circulation efficiency.

2. The portable power battery pack heat dissipation device according to claim 1, characterized in that: The solid-liquid phase change material is composed of paraffin wax, expanded graphite, and copper foam.

3. The portable power battery pack heat dissipation device according to claim 1, characterized in that: The liquid-gas phase change material is made of acetone, carbon nanotube oil-based nanofluid, heat-conducting oil nanofluid, Cu-water nanofluid, or Al2O3 nanofluid.

4. The portable power battery pack heat dissipation device according to any one of claims 1 to 3, characterized in that: The structure of the condensation wall is corrugated in the X direction and corrugated or rectangular in the Y direction.

5. The portable power battery pack heat dissipation device according to claim 4, characterized in that: The lower substrate of the condenser plate also serves as the upper cover of the battery pack, and the lower substrate has multiple through holes; each through hole corresponds to a corresponding evaporator tube, so that the upper end of the evaporator tube leads to the condensation cavity.

6. The portable power battery pack heat dissipation device according to claim 5, characterized in that: The upper part of the transparent cover is equipped with a miniature blower, and the left and right louvers can be equipped with miniature exhaust fans, which transforms the natural convection heat dissipation of the fins into forced convection heat transfer, thereby increasing the heat transfer coefficient and the heat dissipation rate.

7. The portable power battery pack heat dissipation device according to claim 6, characterized in that: The power for the miniature blower and miniature induced draft fan comes from one of the power batteries in the battery pack.

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