A bionic variable-section fin air-cooled phase change material composite cylindrical battery thermal management system

Abstract

The present invention discloses a bionic variable cross-section fin air-cooled phase change material composite cylindrical battery thermal management system, comprising: a fan, a cover plate, an insulating fixed bracket, a base, a cylindrical battery, a bionic variable cross-section fin and a phase change material; the cylindrical battery is radially staggered and nested in the insulating fixed bracket, the bionic variable cross-section fin is embedded in the insulating fixed bracket, the phase change material is filled around the cylindrical battery, the insulating fixed bracket is mounted on the base, the cover plate is mounted on the insulating fixed bracket, and the air is driven by the fan to enter the cooling air duct formed by the insulating fixed bracket, and heat is exchanged with the bionic variable cross-section fin to dissipate the heat of the cylindrical battery and the phase change material to achieve the purpose of temperature control. The present invention has the characteristics of simple structure, convenient installation, high heat dissipation efficiency and low energy consumption, and can ensure the safe and efficient operation of the power battery pack under high-rate charge and discharge cycle conditions.

Description

Technical Field

[0001] The invention relates to the technical field of thermal management of energy storage batteries, and in particular to a bionic variable-section fin air-cooled phase-change material composite cylindrical battery thermal management system. Background Art

[0002] Zero-emission new energy electric vehicles and grid energy storage have played an important role in achieving the goal of "carbon peak and carbon neutrality". Lithium-ion batteries have become the core components of current electric vehicle energy supply and grid energy storage due to their high energy density, high specific power, and long cycle life. However, the electrochemical reaction inside the lithium battery will generate a lot of heat when it is working, causing the temperature to rise. Excessive temperature will cause the performance and cycle life of the lithium battery to seriously decline, and even cause safety problems such as thermal runaway. In order to ensure the efficient and safe operation of lithium-ion batteries, the battery operating temperature should be controlled at 20-40℃ and the temperature difference of the battery pack should be less than 3℃, so an efficient lithium battery thermal management system should be established.

[0003] Air cooling has the characteristics of simple and compact structure and is easy to install and arrange, but the low thermal conductivity and specific heat capacity of air lead to low efficiency of air cooling; phase change material cooling has the advantages of zero energy consumption, strong structural adaptability and good temperature uniformity, but the low thermal conductivity of phase change materials seriously limits its application. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a bionic variable-section fin air-cooled phase change material composite cylindrical battery thermal management system, which has the characteristics of simple structure, easy installation, high heat dissipation efficiency and low energy consumption, and can ensure the safe and efficient operation of the power battery pack under high-rate charge and discharge cycle conditions.

[0005] In order to solve the above technical problems, the present invention provides a bionic variable-section fin air-cooled phase-change material composite cylindrical battery thermal management system, comprising: a fan, a cover plate, an insulating fixed bracket, a base, a cylindrical battery, a bionic variable-section fin and a phase-change material; the cylindrical batteries are radially staggered and nested in the insulating fixed bracket, the bionic variable-section fins are embedded in the insulating fixed bracket, the phase-change material is filled around the cylindrical batteries, the insulating fixed bracket is installed on the base, and the cover plate is installed on the insulating fixed bracket. The air is driven by the fan to enter the cooling air duct formed by the insulating fixed bracket, and heat is exchanged with the bionic variable-section fins to dissipate the heat of the cylindrical batteries and the phase-change material to achieve the purpose of temperature control.

[0006] Preferably, the insulating fixing bracket is made of acrylic material and has a width of 3-5 mm.

[0007] Preferably, one end of the bionic variable-section fin is in circumferential contact with the cylindrical battery, and the other end is exposed to the air flow channel. The cross-sectional area size gradually changes, transferring the heat of the cylindrical battery and the phase change material to the air domain and dissipating it through convection heat exchange.

[0008] Preferably, the bionic variable cross-section fins have four shapes: rectangular, bird-beak, wing and forked, and six bionic variable cross-section fins are evenly distributed around the cylindrical battery.

[0009] Preferably, the cross-sectional size of the bird's beak-shaped bionic variable-section fin gradually decreases from the end in contact with the cylindrical battery to the end exposed to the air domain.

[0010] Preferably, the cross-sectional size of the wing-shaped bionic variable-section fin gradually increases from the end in contact with the cylindrical battery to the end exposed to the air domain.

[0011] Preferably, the tail angle α of the forked bionic variable-section fin is 45°-75°, and the top shape of the fin is the same as the top shape of the bird-beak-shaped fin.

[0012] Preferably, the length of the forked bionic variable-section fin in contact with the cylindrical battery is 70 mm, and the length of the contact with the air space is 70-0 mm, so as to reduce wind resistance and fin weight.

[0013] Preferably, the windward surface of the forked bionic variable-section fin is arc-shaped, which further reduces wind resistance.

[0014] Preferably, the cylindrical batteries are 21700 cylindrical lithium-ion batteries, which are arranged in parallel and staggered at equidistant intervals of 31 mm.

[0015] Preferably, the phase change material component is pure paraffin and has a thickness of 3 mm.

[0016] The beneficial effects of the present invention are as follows: the present invention applies bionic variable-section fins to an air-cooled phase-change material composite thermal management system, which can expand the heat transfer path of the phase-change material to compensate for the disadvantage of low thermal conductivity, enhance the heat exchange efficiency between the battery and the air, and improve the heat dissipation efficiency of the battery pack; the designed bionic variable-section fins have strong adaptability, and the size can be flexibly adjusted according to the battery model and spacing while maintaining the original characteristics of the battery thermal management system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0018] Figure 2 It is a schematic diagram of the system components of the present invention.

[0019] Figure 3 It is a top view of the battery module in the present invention.

[0020] FIG. 4( a ) is a partial top view of the battery module of the present invention.

[0021] FIG4( b ) is a partial cross-sectional view of the battery module of the present invention.

[0022] Figure 5 It is a schematic diagram of the structure of bionic variable cross-section fins of different shapes in the present invention.

[0023] FIG. 6( a ) is a schematic diagram of structural parameters of a bifurcated bionic variable cross-section fin in the present invention.

[0024] FIG. 6( b ) is a schematic diagram of the optimization of the windward surface of the forked bionic variable-section fin of the present invention.

[0025] FIG. 7( a ) is a schematic diagram showing the change in temperature of a battery module according to the present invention with respect to flow rate.

[0026] FIG. 7( b ) is a schematic diagram showing the variation of power consumption of a single flow channel with flow velocity according to the present invention.

[0027] FIG8( a ) is a schematic diagram showing the variation of the temperature of the battery module according to the present invention with the width of the insulating fixing bracket.

[0028] FIG8( b ) is a schematic diagram showing the variation of the power consumption of a single flow channel with the width of the insulating fixing bracket according to the present invention.

[0029] FIG. 9( a ) is a schematic diagram showing the variation of the temperature of the battery module according to the present invention with the length of the bionic variable-section fin.

[0030] FIG9( b ) is a schematic diagram showing the variation of the power consumption of a single flow channel with the length of the bionic variable cross-section fin of the present invention.

[0031] Fig.10 Schematic diagram of the maximum temperature and temperature difference of the battery module changing with time under the delayed cooling scheme of the present invention.

[0032] Among them, 1. Fan; 2. Cover; 3. Insulation fixing bracket; 4. Base; 5. Cylindrical battery; 6. Bionic variable cross-section fin; 7. Phase change material. DETAILED DESCRIPTION

[0033] like Figure 1 and Figure 2 As shown, a bionic variable-section fin air-cooled phase-change material composite cylindrical battery thermal management system comprises: a fan 1, a cover plate 2, an insulating fixed bracket 3, a base 4, a cylindrical battery 5, a bionic variable-section fin 6 and a phase-change material 7; the cylindrical battery 5 is radially staggered and nested in the insulating fixed bracket 3, the bionic variable-section fin 6 is embedded in the insulating fixed bracket 3, the phase-change material 7 is filled around the cylindrical battery 5, the insulating fixed bracket 3 is mounted on the base 4, and the cover plate 2 is mounted on the insulating fixed bracket 3. The air is driven by the fan 1 to enter the cooling air duct formed by the insulating fixed bracket 3, and heat is exchanged with the bionic variable-section fin 6 to dissipate the heat of the cylindrical battery 5 and the phase-change material 7 to achieve the purpose of temperature control.

[0034] like Figure 3As shown, the thickness of the phase change material 7 is 3 mm, and the component is pure paraffin. When the temperature of the cylindrical battery reaches the melting point of the phase change material, the latent heat of the phase change material takes effect to absorb the heat of the cylindrical lithium power battery to achieve temperature control.

[0035] As shown in FIG. 4( a ) and FIG. 4( b ), the insulating fixing bracket 3 constitutes an air flow channel, and the air is driven by the fan 1 to pass through the flow channel axially to take away the heat of the battery pack; the insulating fixing bracket 3 is made of acrylic material with a width of 3-5 mm.

[0036] The bionic variable cross-section fin 6 has four shapes: rectangular, bird-beak, wing-shaped and forked, respectively. Figure 5 As shown. The cross-sectional area of ​​the bionic variable cross-section fin 6 is 9.4 mm 2 , the length of the tail end of the bionic variable cross-section fin 6 is equal to the height of the cylindrical battery 5, and the value is 70mm. Figure 5 The bionic variable cross-section fin 6 can expand the heat conduction path of the phase change material 7 to make up for the low thermal conductivity of the phase change material. The bionic variable cross-section fin can transfer the heat generated by the cylindrical battery 5 and the heat stored in the phase change material 7 to the air domain and dissipate it through convection heat exchange.

[0037] The battery pack temperature of different fin cooling models changes with wind speed as shown in Figure 7(a). Under the 3C charging and 4C discharging cycle conditions of cylindrical battery 5, when the wind speed increases from 0m / s to 5m / s, the maximum temperature of the battery pack gradually decreases and the temperature difference gradually increases. The forked fins have the best heat dissipation performance at different flow rates. When the wind speed is 5m / s, the forked fin cooling model reduces the maximum temperature of the battery pack by 3.6°C compared to the maximum temperature of 41.5°C of the cooling model without adding fins. In addition, as shown in Figure 7(b), the power consumption of the cooling model increases with the increase of wind speed. When the wind speed exceeds 3m / s, the power consumption increment increases significantly. Compared with the other three types of fin cooling models, the power consumption of the forked fin cooling model at different flow rates is the smallest. When the wind speed is 3m / s, the power consumption of a single flow channel of the forked fin cooling model is 11×10 -3 W.

[0038] like Figure 6(a) and 6(b) As shown, the top length L2 of the bifurcated fin bionic variable cross-section fin 6 is 70mm-0mm. According to the operation of the battery module, when the inlet wind speed is 3m / s, the width L1 of the insulating fixing bracket 3 and the top length L2 of the bionic variable cross-section fin 6 can be changed accordingly to improve the heat dissipation performance of the battery pack and reduce the air cooling power consumption.

[0039] Under the 3C charging and 4C discharging conditions of cylindrical battery 5, the heat dissipation performance of the battery pack is almost the same when the width of the insulating bracket 3 is adjusted from 3mm to 5mm, as shown in Figure 8(a). However, when the width of the insulating bracket 3 is 4mm, the power consumption of the heat dissipation model is the smallest, and the pressure difference and power consumption generated by a single air cooling channel are 17.4Pa and 3×10 -3 W, as shown in Figure 8(b). In addition, the maximum temperature of the battery pack increases with the decrease of L2, while the temperature difference of the battery pack decreases first and then increases, as shown in Figure 9(a); the power consumption of the heat dissipation model decreases with the decrease of L2, as shown in Figure 9(b). Weighing the temperature control performance and power consumption of the battery thermal management system, the optimal length value of L2 is 40mm. Under this parameter, the maximum temperature and temperature difference of the battery pack are 38.9℃ and 2.9℃ respectively.

[0040] In order to reduce the power consumption of air cooling, a delayed cooling strategy can be adopted. Although the cylindrical battery 5 generates heat during 3C charging, causing the battery temperature to rise, when the temperature reaches the melting point of the phase change material 7, 34°C, the phase change material 7 uses its high latent heat characteristics to absorb the heat of the battery and keep the temperature within the melting point range (34°C-36°C). If the air cooling is not started during the 1208s of the 3C charging process, the energy consumption can be reduced by 59%. At the end of the discharge, the maximum temperature and temperature difference of the battery pack are 39.5°C and 2.9°C respectively, which still meet the heat dissipation requirements. Fig.10 shown.

[0041] The present invention is effective for heat dissipation of cylindrical battery packs. The 21700 cylindrical battery 5 in the present invention can also be 18650, 26650, 4680, etc. At the same time, when the battery distribution spacing and arrangement method are changed, the present invention is also applicable.

Claims

1. A bionic variable cross-section fin air-cooled phase change material composite cylindrical battery thermal management system, characterized in that: include: A fan, a cover plate, an insulating fixed bracket, a base, a cylindrical battery, a bionic variable-section fin and a phase-change material; the cylindrical battery is radially interlaced and nested in the insulating fixed bracket, the bionic variable-section fin is embedded in the insulating fixed bracket, the phase-change material is filled around the cylindrical battery, the insulating fixed bracket is mounted on the base, the cover plate is mounted on the insulating fixed bracket, and the air is driven by the fan to enter the cooling air duct formed by the insulating fixed bracket, and heat is exchanged with the bionic variable-section fin to dissipate the heat of the cylindrical battery and the phase-change material; One end of the bionic variable-section fin is in contact with the cylindrical battery circumferentially, and the other end is exposed to the air flow channel. The cross-sectional area size gradually changes, and the heat of the cylindrical battery and the phase change material is transferred to the air domain and dissipated through convection heat exchange; the bionic variable-section fin has three shapes: bird's beak, wing and forked. Six bionic variable-section fins are evenly distributed around the cylindrical battery; the cross-sectional size of the bird's beak-shaped bionic variable-section fin gradually decreases from the end in contact with the cylindrical battery to the end exposed to the air domain; the wing-shaped bionic variable-section fin The cross-sectional size of the cross-sectional fin gradually increases from the end in contact with the cylindrical battery to the end exposed to the air domain; the tail angle α of the forked bionic variable cross-sectional fin is 45°-75°, the top shape of the fin is the same as the top shape of the bird-beak shaped fin, the length of the forked bionic variable cross-sectional fin in contact with the cylindrical battery is 70mm, and the length of the end in contact with the air domain is 70-0mm, the windward surface of the forked bionic variable cross-sectional fin is arc-shaped, and the bottom fork of the forked bionic variable cross-sectional fin is in circumferential contact with the cylindrical battery.

2. The bionic variable cross-section fin air-cooled phase change material composite cylindrical battery thermal management system according to claim 1, characterized in that: The insulating fixing bracket is made of acrylic material and has a width of 3-5mm.

3. The bionic variable cross-section fin air-cooled phase change material composite cylindrical battery thermal management system according to claim 1, characterized in that: The cylindrical batteries are 21700 cylindrical lithium-ion batteries, arranged in parallel and staggered at 31mm intervals.

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