Air-cooled battery pack based on two-phase flow phase change temperature equalization

Abstract

The invention relates to an air-cooled battery pack based on two-phase flow phase change temperature equalization, and belongs to the technical field of air-cooled energy storage. The air-cooled battery pack comprises a shell and a battery module, a fan is arranged at the front end of the shell, openings are formed in the rear end and the side face of the shell, a two-phase flow temperature equalizing plate is arranged at the bottom of the shell and comprises a temperature equalizing plate body and a cavity, and an evaporation area and condensation areas located on the two sides of an evaporator are arranged in the cavity. Through the holes in the rear end and the side face of the air-cooled battery pack, cold air flow provided by the energy storage system can be introduced into the battery pack from the rear end and the two sides of the battery pack, the air flow in the battery pack is pumped out through the fan, the situation that the temperature of the rear portion of the battery pack is too high is avoided, and circulating air cooling capable of restraining the front-back heat cascade phenomenon is achieved; excessive heat in the middle of the battery pack is dispersed to the front side and the rear side through the two-phase flow temperature equalizing plate, and the temperature equalizing performance of the battery pack can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of air-cooled energy storage, and in particular relates to an air-cooled battery pack based on two-phase flow phase change temperature equalization. Background Art

[0002] Energy storage systems are widely used in industry, commerce, data centers and other fields. The heat dissipation performance of the battery pack, its core component, directly affects the safety and life of the system. At present, the heat dissipation methods of energy storage systems are mainly divided into air cooling and liquid cooling. Compared with liquid cooling, air cooling is widely used in industrial and commercial energy storage systems due to its lower initial investment and operation and maintenance costs. However, air cooling technology is limited by the low heat capacity of air and difficult flow control. Its heat dissipation capacity is weak and the temperature consistency is poor. Especially in high-power and high-energy density scenarios, it is difficult to meet the needs.

[0003] In the traditional air-cooled battery pack design, cold air is provided by the air conditioner of the energy storage system. The cold air enters the battery pack air duct from the rear, takes away the heat emitted by the battery cells, and is discharged from the air outlet in front of the battery pack. The above battery pack design can quickly reduce the temperature inside the battery pack, however, it still has some shortcomings. On the one hand, the cold air flow gradually heats up in the process of passing through the air duct in the pack, resulting in poor cooling effect in the front part of the battery pack, and there will be thermal cascades from back to front in the battery pack. On the other hand, the energy storage system composed of multiple battery packs requires complex air duct design to ensure temperature consistency, which increases the difficulty and cost of research and development. Therefore, improving the heat dissipation performance and temperature uniformity of air-cooled battery packs has become a key technical problem. Summary of the invention

[0004] The purpose of the present invention is to provide an air-cooled battery pack based on two-phase flow phase change temperature equalization in order to solve the above problems, so as to overcome the thermal cascade effect before and after the battery pack and reduce the difficulty of air duct design of the energy storage system.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A two-phase flow phase change temperature-equalizing air-cooled battery pack comprises a shell and a battery module arranged inside the shell, a fan is provided at the front end of the shell, and openings are provided at the rear end and sides of the shell to guide the cold air flow from the rear end and sides of the air-cooled battery pack into the interior of the air-cooled battery pack, and a two-phase flow temperature-equalizing plate is provided at the bottom of the shell.

[0007] The two-phase flow temperature averaging plate comprises a temperature averaging plate body and a cavity provided in the temperature averaging plate body, wherein the cavity is used to fill the refrigerant, and a step is provided in the cavity. The step divides the cavity into an evaporation zone and two condensation zones located at the front and rear sides of the evaporation zone, respectively. The refrigerant is vaporized in the evaporation zone and liquefied in the condensation zone, and the liquefied refrigerant flows back to the evaporation zone through the step.

[0008] As a further optimization solution of the present invention, the depths of the two condensation zones are shallower than the depth of the evaporation zone.

[0009] As a further optimization solution of the present invention, the inner wall of the cavity is provided with roughened surface micro-features, and the cavity is filled with a capillary structure.

[0010] As a further optimization solution of the present invention, the capillary structure is arranged in the evaporation zone, and the capillary structure is aluminum foil and / or metal mesh.

[0011] As a further optimization solution of the present invention, the bottoms of the evaporation zone and the condensation zone both protrude upward to form bosses.

[0012] As a further optimization solution of the present invention, the steps are also used to divide the evaporation area and / or the condensation area into a plurality of sub-areas.

[0013] As a further optimization scheme of the present invention, the steps are divided into two step one and two step two, the two step one are respectively located at the front and rear ends of the evaporation zone, and the two step two are respectively located at the end close to the two condensation zones. A uniform temperature zone is formed between step one and step two at the rear of the cavity and between step one and step two at the front of the cavity, and a flow channel is provided between the evaporation zone and the two condensation zones.

[0014] As a further optimization scheme of the present invention, the flow channel includes a gas flow channel and a liquid flow channel. The gas flow channel is provided on both sides of the uniform temperature zone, and the liquid flow channel is provided in the middle of the uniform temperature zone. The height of the gas flow channel is higher than that of the liquid flow channel.

[0015] As a further optimization scheme of the present invention, the shell is composed of a lower shell and an upper shell that are engaged with each other, and the openings are divided into a group of first openings and two groups of second openings. The first openings are arranged at the rear end of the upper shell, and the second openings are arranged on the side of the upper shell, and the two groups of second openings are arranged close to the front end of the upper shell.

[0016] As a further optimization solution of the present invention, two battery modules are provided inside the shell, air ducts are formed between the shell and the battery module and between the two battery modules, and the fan is arranged in the middle of the front end of the shell.

[0017] The beneficial effects of the present invention are:

[0018] 1) The present invention sets openings at the rear end of the air-cooled battery pack and the middle front part of its side, so that the cold airflow provided by the energy storage system can be introduced into the battery pack from the rear end and both sides of the battery pack, and the airflow in the battery pack can be extracted by a fan, which can effectively avoid the situation where the temperature at the rear of the battery pack is too high, realize circulating air cooling that can suppress the front and rear thermal cascade phenomenon, improve the temperature uniformity of the battery pack, and disperse the excess heat in the middle area of ​​the battery pack to the front and rear sides through a two-phase flow temperature averaging plate, further improving the heat exchange efficiency and temperature uniformity of the battery pack;

[0019] 2) The steps of the present invention divide the cavity of the temperature homogenizing plate into an evaporation zone and condensation zones located on both sides of the evaporation zone. Through the capillary structure in the evaporation zone, the roughening treatment of the cavity and the stepped distribution design, the liquefied refrigerant in the condensation zone can flow back to the evaporation zone. The depth of the condensation zone is shallower than that of the evaporation zone. By setting the steps, the liquid refrigerant can flow back to the evaporation zone more easily, reducing the maximum temperature in the battery pack. The maximum temperature difference in the battery pack is less than 3°C, making the temperature distribution in the battery pack more uniform, reducing the difficulty of the air duct design of the energy storage system, and making it easier for energy storage products to meet development requirements;

[0020] 3) The present invention separates the uniform temperature zone between the evaporation zone and the condensation zone by steps, and sets gas flow channels and liquid flow channels in the uniform temperature zone. Since the temperature of the battery cell above the uniform temperature zone is centered, a heat exchange cavity is not set in this area. The gaseous refrigerant carrying heat in the evaporation zone is concentrated in the condensation zone with a lower temperature to release heat, and the liquid refrigerant carrying cold in the condensation zone is concentrated in the evaporation zone with a higher temperature to absorb heat, so as to improve the heat exchange efficiency of the two-phase flow uniform temperature plate and further improve the temperature uniformity of the air-cooled battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is an assembly diagram of an air-cooled battery pack of the present invention;

[0022] Figure 2 is an exploded view of the air-cooled battery pack of the present invention;

[0023] Figure 3 2 is a schematic diagram of the structure of a two-phase flow temperature averaging plate according to the first embodiment of the present invention;

[0024] Figure 4 is a cross-sectional view of a two-phase flow temperature averaging plate according to a first embodiment of the present invention;

[0025] Figure 5 yes Figure 4 Schematic diagram of the local structure at A in the middle;

[0026] Figure 6 It is a cell temperature cloud diagram of a simple parallel battery pack;

[0027] Figure 7 It is the cell temperature cloud diagram of the two-phase flow battery pack;

[0028] Figure 8 2 is a schematic diagram of the structure of a two-phase flow temperature averaging plate according to a second embodiment of the present invention;

[0029] Fig. 9 yes Figure 8 Enlarged view of point B in the middle.

[0030] In the figure: 1. shell; 2. battery module; 3. fan; 4. two-phase flow uniform temperature plate; 5. battery rack; 6. three-dimensional mesh structure; 11. lower shell; 12. upper shell; 12a. first opening; 12b. second opening; 41. uniform temperature plate body; 42. cavity; 43. step; 43a. step one; 43b. step two; 44. boss; 45. guide platform; 46. gas flow channel; 47. liquid flow channel; E. evaporation zone; C. condensation zone; M. uniform temperature zone. DETAILED DESCRIPTION

[0031] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0032] In the existing energy storage systems on the market, the cold air blown by the system air conditioner enters the air inlet of each battery pack through the system air duct and flows into the battery pack. The battery cells are arranged inside the battery pack and there are air ducts. The fluid takes away the heat of the battery cells through the air duct, flows out from the battery pack outlet, and merges into the system air conditioner return air vent to complete a cycle. The battery pack has the following problems: ① There will be a thermal cascade from the back to the front of the pack, and the temperature consistency of the battery cells is poor; ② The energy storage system is assembled from multiple battery packs, and a complex system air duct design is required to ensure temperature consistency, which is difficult to design.

[0033] To this end, the present invention designs an air-cooled battery pack that can overcome the thermal cascade effect within the pack and reduce the difficulty of system air duct design.

[0034] First embodiment

[0035] like Figure 1 and Figure 2 As shown, the present embodiment relates to an air-cooled battery pack based on two-phase flow phase change temperature equalization. The battery pack consists of a shell 1, a battery module 2 arranged inside the shell 1, and a fan 3 arranged at the front end of the shell 1. The rear end and side of the shell 1 are provided with openings for introducing the cold air flow from the rear end and side of the air-cooled battery pack into the interior of the air-cooled battery pack. A two-phase flow temperature equalizing plate 4 is fixedly provided at the bottom of the shell 1. By improving the inlet mode of the air-cooled battery pack and the two-phase flow temperature equalizing plate 4 at the bottom of the battery pack, the temperature uniformity of the air-cooled battery pack carrier can be effectively improved.

[0036] It should be noted that, assuming that only the rear end and side openings of the shell 1 are provided without the two-phase flow temperature equalizing plate 4, the large temperature difference between the front and rear sides of the air-cooled battery pack can be avoided. However, the air-cooled battery pack as a whole will show a higher temperature in the middle. Therefore, if the difficulty of air duct design needs to be reduced, the temperature uniformity of the air-cooled battery pack needs to be further improved. Therefore, this embodiment uses a two-phase flow temperature equalizing plate 4 to equalize the temperature inside the air-cooled battery pack.

[0037] See also Figure 3-5 , the two-phase flow temperature averaging plate 4 includes a temperature averaging plate body 41 and a cavity 42 provided in the temperature averaging plate body 41, the cavity 42 is used to fill the refrigerant, and at least two steps 43 are provided in the cavity 42. The refrigerant inside the cavity 42 is preferably R134a, and R134a is 1,1,1,2-tetrafluoroethane. The refrigerant has the properties of low boiling point, high evaporation pressure, low condensation pressure, large latent heat, high chemical stability, environmental protection and low conductivity. In some other embodiments, other fluids of the same nature can also be used as refrigerants to replace R134a. The step 43 divides the cavity 42 into an evaporation zone E and two condensation zones C located on the front and rear sides of the evaporation zone E. The depths of the two condensation zones C are shallower than the depth of the evaporation zone E. The refrigerant is vaporized by the evaporation zone E and liquefied in the condensation zone C, and the liquefied refrigerant flows back to the evaporation zone E through the step 43. And prevent the situation where the temperature in the middle of the battery pack is significantly higher than the temperature in the rear and front of the battery pack.

[0038] Specifically, if Figure 2 As shown, the shell 1 is divided into a lower shell 11 and an upper shell 12, the lower shell 11 is provided with an opening at the top, and the upper shell 12 is provided with an opening at the bottom. The upper shell 12 is engaged with the outer side of the lower shell 11, and an assembly hole corresponding to the fan 3 is provided in the middle of the front end of the lower shell 11. Each air-cooled battery pack in this embodiment is provided with two fans 3, and accordingly, two upper and lower assembly holes are provided at the front end of the lower shell 11. The side wall of the lower shell 11 has a U-shaped notch on one side, and the notch corresponds to the openings at the rear end and side of the shell 1. The above-mentioned openings are divided into a group of first openings 12a and two groups of second openings 12b, the first opening 12a is provided at the rear end of the upper shell 12, and the second opening 12b is provided at the side of the upper shell 12. Both groups of second openings 12b are provided close to the front end of the upper shell 12, that is, the second openings 12b are located in the middle and front of the side of the upper shell 12.

[0039] There are two battery modules 2 inside the shell 1, and air ducts are formed between the shell 1 and the battery module 2 and between the two battery modules 2. The fan 3 is arranged in the middle of the front end of the shell 1. Each battery module 2 is composed of a row of battery cells. A battery rack 5 is fixedly arranged on the bottom wall of the lower shell 11, and the battery cells of the two battery modules 2 are fixedly arranged on the battery rack 5. In this embodiment, the side surface of the shell 1 is the end surface in the width direction of the shell 1, and similarly, the side surface of the upper shell 12 is also the end surface in the width direction of the upper shell 12. A gap is formed between the two rows of battery cells, a gap is formed between the side wall at the front end of the lower shell 11 and the two rows of battery cells, a gap is formed between the two rows of battery cells and the side walls on the two sides of the upper shell 12, a gap is formed between the side wall at the rear end of the upper shell 12 and the two rows of battery cells, and a gap is also formed between the top wall of the upper shell 12 and each battery cell. The above gaps together constitute the air duct inside the air-cooled battery pack.

[0040] The air-cooled battery pack is in an energy storage system with a built-in air conditioner. During the charging and discharging process of the air-cooled battery pack, the air conditioner provides cold air flow to the air-cooled battery pack, and the cold air flow is pumped by the fan 3, which is located in front of the air-cooled battery pack. The cold air flow discharged from the air outlet of the air conditioner flows into the air duct inside the air-cooled battery pack from a group of first openings 12a at the rear end of the air-cooled battery pack and two groups of second openings 12b on the two sides. Before, under the action of the fan 3, the air flow in the air-cooled battery pack is pumped out and flows into the return air outlet of the air conditioner, completing an air cooling cycle.

[0041] During the air cooling cycle, part of the cold air flow outside the air-cooled battery pack enters the middle front area of ​​the air-cooled battery pack through the second opening 12b, which can avoid the phenomenon that the temperature of the front battery cell in the air-cooled battery pack is significantly higher than the temperature of the rear battery cell.

[0042] On this basis, the temperature in the air-cooled battery pack is balanced by the two-phase flow temperature equalizing plate 4. The inner wall of the cavity 42 of the two-phase flow temperature equalizing plate 4 is provided with roughened surface micro-features, and the evaporation zone E in the cavity 42 is filled with a capillary structure. The liquid refrigerant in the evaporation zone E in the middle of the two-phase flow temperature equalizing plate 4 evaporates and absorbs heat to form a gaseous refrigerant. The gaseous refrigerant previously flows from the evaporation zone E to the condensation zones C on both sides of it to liquefy and release heat, and re-forms the liquid refrigerant. The liquid refrigerant in the condensation zone C flows back to the evaporation zone E under the capillary action of the capillary structure. Since a step 43 is provided between the evaporation zone E and the two condensation zones C, under the action of gravity, the liquid refrigerant in the condensation zone C is easier to flow back to the evaporation zone E, achieving high thermal conductivity, uniform temperature of each battery cell, improving the temperature equalization effect, and further improving the temperature uniformity of the air-cooled battery pack.

[0043] See also Figure 6 and Figure 7 ,in Figure 6It is a cell temperature cloud diagram of a simple parallel battery pack. In the corresponding battery pack design, the simple parallel battery pack has holes at its rear end and side, and a fan is provided at the front end of the battery pack instead of a temperature equalizing plate. Figure 7 The temperature cloud diagram of the battery cell of the two-phase flow battery pack corresponds to the battery pack design scheme. The two-phase flow battery pack is the air-cooled battery pack in this embodiment. Not only the first opening 12a and the second opening 12b are provided on the shell 1, a fan 3 is provided at the front end of the shell 1, and the bottom of the shell 1 is provided as shown in FIG. Figure 3 The two-phase flow temperature equalizing plate 4 shown redistributes the heat of each battery cell in the air-cooled battery pack through capillary action and step-distributed design.

[0044] from Figure 6 It can be seen that without setting the two-phase flow temperature plate 4, the highest temperature of the monitoring point is 35°C, the lowest temperature is 29.3°C, and the maximum temperature difference is 5.7°C. Under this scheme, the temperature distribution of the battery pack is relatively even, the maximum temperature difference is between 5°C and 10°C, and the overall temperature of the front of the battery pack is smaller than that of the rear. However, the middle front area of ​​the battery pack still has a large temperature difference compared with the front and rear ends, and the temperature uniformity of the battery pack still needs to be improved.

[0045] from Figure 7 It can be seen that when the two-phase flow temperature averaging plate 4 is set, the maximum temperature of the monitoring point is 33.7°C, the minimum temperature is 30.9°C, and the maximum temperature difference is 2.8°C. Compared with the case where the two-phase flow temperature averaging plate 4 is not set, the maximum temperature of this embodiment is lowered, the minimum temperature is increased, and the maximum temperature difference can be reduced to within 3°C. There is no phenomenon of a large temperature difference between the front and rear sides, nor is there a phenomenon that the temperature in the middle is significantly higher than the temperatures on the front and rear sides.

[0046] It can be seen from this that Figure 7 The corresponding battery pack design scheme further improves the temperature uniformity of the battery pack. Since the temperature uniformity of a single battery pack is good, when the temperature uniformity requirements are the same, the difficulty of the energy storage system air duct design can be reduced, making it easier for energy storage products to meet development and design requirements.

[0047] Preferably, the surface micro-features of the inner wall of the cavity 42 are processed by laser engraving, sandblasting and other processes, which can enhance the capillary effect of the liquid refrigerant during reflux, increase the roughness and heat absorption area of ​​the cavity 42, and further improve the heat exchange efficiency of the air-cooled battery pack. The capillary structure in the evaporation zone E is preferably a metal mesh. In other embodiments, the capillary structure can also be made of aluminum foil with fine wrinkles on the surface. In addition, in other embodiments, a composite structure composed of aluminum foil and a metal mesh can also be used as the capillary structure. The main function of the aluminum foil is to increase the heat exchange area. The metal mesh is located above the aluminum foil, and can quickly conduct the liquid refrigerant at the bottom of the evaporation zone E to the upper part.

[0048] It should be noted that the capillary structure inside the temperature equalizing plate body 41 has different functions in the evaporation zone E and the condensation zone C. In order to store a larger proportion of liquid refrigerant, the two ends of the evaporation zone E are made into a step shape. However, since the liquid refrigerant is close to the lower part and the heat source is in the upper part, in order to improve the efficiency, it is necessary to increase the heat exchange area and increase the heat exchange efficiency. It is also necessary to conduct the liquid refrigerant at the bottom to the upper part more quickly to evaporate and take away the heat. The capillary structure of the evaporation zone E is mainly to achieve the above functions. The aluminum foil is mainly used to increase the heat exchange area of ​​the evaporation zone; the metal mesh provides capillary action and can also increase the heat exchange area. The capillary structure of the condensation zone C is to quickly guide the liquid refrigerant condensed in the condensation zone C back to the evaporation zone E.

[0049] Furthermore, in some other embodiments, the step 43 is also used to divide the evaporation zone E and the condensation zone C into multiple sub-areas. That is, the number of steps 43 in the cavity 42 can be increased according to the test results of the heat dissipation experiment. Steps 43 can be added in the evaporation zone E to make it easier for the liquid refrigerant to flow to the hotter local area in the evaporation zone E. Steps 43 can also be added in the condensation zone C to allow the liquid refrigerant to flow faster from the condensation zone C to the evaporation zone E. In some other embodiments, steps 43 can also be added only in the evaporation zone E or only in the condensation zone C to divide the evaporation zone E or the condensation zone C into detailed areas.

[0050] By dividing the evaporation zone E and the condensation zone C into multiple sub-zones, the number of steps 43 in the two-phase flow temperature equalizing plate 4 can be set according to different temperature ranges, thereby adjusting the amount of liquid refrigerant in each zone, so that the amount of liquid refrigerant in the high-temperature zone is larger, thereby accelerating the heat exchange efficiency.

[0051] In addition, the temperature plate body 41 is fixed to the bottom of the lower shell 11 in an integrated brazing manner. The bottoms of the evaporation zone E and the condensation zone C both protrude upward to form a plurality of evenly distributed bosses 44. By providing the bosses 44 at the bottoms of the evaporation zone E and the condensation zone C, the heat exchange area of ​​the cavity 42 can be increased. The bosses 44 are also provided with the above-mentioned surface micro-features, which further increase the heat exchange area of ​​the cavity 42 and improve the capillary effect.

[0052] In addition, the upper surfaces of the bosses 44 in different areas of the cavity 42 are of the same height, and the top of the bosses 44 is of the same height as the upper edge of the temperature averaging plate body 41. During the integrated brazing process, the upper edge of the temperature averaging plate body 41 and the top of the bosses 44 melt and are welded to the bottom of the lower shell 11. The bosses 44 can not only increase the heat exchange area and improve the capillary effect, but also support and shape the cavity 42 of the two-phase flow temperature averaging plate 4. This avoids the phenomenon of reduced temperature averaging effect due to deformation of the local area of ​​the evaporation zone E or the condensation zone C.

[0053] Second embodiment

[0054] This embodiment relates to another air-cooled battery pack based on two-phase flow phase change temperature equalization, such as Figure 8 and Fig. 9 As shown, the difference between the air-cooled battery pack of this embodiment and the previous embodiment is that another stepped distributed two-phase flow temperature averaging plate 4 ′ is designed, and the other structures of the air-cooled battery pack are the same as those of the previous embodiment.

[0055] The step 43 in this embodiment is divided into two steps 1 43a and two steps 2 43b. The two steps 1 43a are respectively located at the front and rear ends of the evaporation zone E, and the two steps 2 43b are respectively located at the end close to the two condensation zones C. A uniform temperature zone M is formed between the step 1 43a and the step 2 43b at the rear of the cavity 42 and between the step 1 43a and the step 2 43b at the front of the cavity 42. A flow channel is provided between the evaporation zone E and the two condensation zones C. The depth of the bottom of the step 1 43a is greater than the depth of the bottom of the step 2 43b, so that the bottom of the condensation zone C is higher than the bottom of the evaporation zone E.

[0056] The flow channel includes a gas flow channel 46 and a liquid flow channel 47. The gas flow channels 46 are provided on both sides of the uniform temperature zone M, and the liquid flow channel 47 is provided in the middle of the uniform temperature zone M. The height of the gas flow channel 46 is higher than that of the liquid flow channel 47. In this embodiment, the uniform temperature zone M protrudes upward to form a guide platform 45. The upper openings on both sides of the guide platform 45 are provided. The gas flow channel 46 is located at the upper openings on both sides of the guide platform 45. The liquid flow channel 47 runs through the middle of the guide platform 45. The top of the guide platform 45 is flush with the top of the edge of the uniform temperature plate body 41 and can be welded to the bottom of the lower shell 11. The height of the bottom of the liquid flow channel 47 does not exceed the bottom of the condensation zone C, and the height of the bottom of the liquid flow channel 47 is higher than the bottom of the evaporation zone E.

[0057] In this embodiment, considering that the temperature of the battery core above the uniform temperature zone M is in the middle, the heat exchange cavity 42 is not provided in this area. Compared with the previous embodiment, the gaseous refrigerant carrying heat in the evaporation zone E is concentrated in the condensation zone C with a lower temperature to release heat, and the liquid refrigerant carrying cold in the condensation zone C is concentrated in the evaporation zone E with a higher temperature to absorb heat, so as to improve the heat exchange efficiency of the two-phase flow uniform temperature plate 4'.

[0058] In addition, Fig. 9As shown, the capillary structure in the evaporation zone E in this embodiment includes a three-dimensional mesh structure 6, which is composed of a plurality of transverse wavy metal wires and a plurality of longitudinal wavy metal wires, the crests of the transverse wavy metal wires are located above the troughs of the longitudinal wavy metal wires, and the troughs of the transverse wavy metal wires are located below the crests of the longitudinal wavy metal wires. The three-dimensional mesh structure 6 can provide capillary force for the liquid flow channel 47 and the liquid refrigerant at the bottom of the evaporation zone E, and increase the refrigerant heat exchange rate, so that the refrigerant in the liquid flow channel 47 quickly enters the evaporation zone E, and the refrigerant at the bottom of the evaporation zone E flows upward and evaporates quickly.

[0059] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An air-cooled battery pack based on two-phase flow phase change temperature equalization, comprising a housing (1), and a battery module (2) arranged inside the housing (1), characterized in that: A fan (3) is provided at the front end of the shell (1), and openings are provided at the rear end and side surfaces of the shell (1) for introducing a cold air flow from the rear end and side surfaces of the air-cooled battery pack into the interior of the air-cooled battery pack, and a two-phase flow temperature averaging plate (4) is provided at the bottom of the shell (1); The two-phase flow temperature equalizing plate (4) comprises a temperature equalizing plate body (41) and a cavity (42) arranged in the temperature equalizing plate body (41); the cavity (42) is used to fill the refrigerant, and a step (43) is arranged in the cavity (42); the step (43) divides the cavity (42) into an evaporation zone and two condensation zones located at the front and rear sides of the evaporation zone respectively; the refrigerant is vaporized in the evaporation zone and liquefied in the condensation zone, and the liquefied refrigerant flows back to the evaporation zone through the step (43).

2. The air-cooled battery pack according to claim 1, characterized in that: The depths of the two condensation zones are shallower than that of the evaporation zone.

3. The air-cooled battery pack according to claim 2, characterized in that: The inner wall of the cavity (42) is provided with roughened surface micro-features, and the cavity (42) is filled with a capillary structure.

4. The air-cooled battery pack according to claim 3, characterized in that: The capillary structure is arranged in the evaporation zone, and the capillary structure is aluminum foil and / or metal mesh.

5. The air-cooled battery pack according to claim 3, characterized in that: The bottoms of the evaporation zone and the condensation zone both protrude upward to form bosses (44).

6. The air-cooled battery pack according to claim 1, characterized in that: The steps (43) are also used to divide the evaporation area and / or the condensation area into a plurality of sub-areas.

7. The air-cooled battery pack according to claim 1, characterized in that: The step (43) is divided into two step one (43a) and two step two (43b), the two step one (43a) are respectively located at the front and rear ends of the evaporation zone, and the two step two (43b) are respectively located at the end close to the two condensation zones, and a uniform temperature zone is formed between the step one (43a) and the step two (43b) at the rear of the cavity (42) and between the step one (43a) and the step two (43b) at the front of the cavity (42), and a flow channel is provided between the evaporation zone and the two condensation zones.

8. The air-cooled battery pack according to claim 7, characterized in that: The flow channel comprises a gas flow channel (46) and a liquid flow channel (47); the gas flow channel (46) is provided on both sides of the uniform temperature zone, and the liquid flow channel (47) is provided in the middle of the uniform temperature zone; the height of the gas flow channel (46) is higher than that of the liquid flow channel (47).

9. The air-cooled battery pack according to claim 1, characterized in that: The shell (1) is composed of a lower shell (11) and an upper shell (12) which are engaged with each other, and the openings are divided into a group of first openings (12a) and two groups of second openings (12b), wherein the first openings (12a) are arranged at the rear end of the upper shell (12), and the second openings (12b) are arranged at the side of the upper shell (12), and the two groups of second openings (12b) are arranged close to the front end of the upper shell (12).

10. The air-cooled battery pack according to claim 1, characterized in that: Two battery modules (2) are provided inside the shell (1), air ducts are formed between the shell (1) and the battery modules (2) and between the two battery modules (2), and the fan (3) is arranged in the middle of the front end of the shell (1).

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