Series flow field based air-cooled fuel cell and thermal management method thereof

Abstract

This invention discloses an air-cooled fuel cell based on a series flow field, comprising: a fuel cell stack with an installation end face; a series flow field structure integrated on the fuel cell stack, including independently connected cooling channels, a flow splitter assembly, and a cathode reaction channel; wherein, the independently connected cooling channels have an independent cooling channel inlet and an independent cooling channel outlet, both disposed on the installation end face; the cathode reaction channel has a cathode reaction channel inlet and a cathode reaction channel outlet, both disposed on the installation end face; the flow splitter assembly is disposed on the outer side of the installation end face and connects the outlet of the independently connected cooling channels to the inlet of the cathode reaction channel; and a fan is disposed on the installation end face and connected to the inlet of the independently connected cooling channels. This invention enables a single fan to supply air to both the independently connected cooling channels and the cathode reaction channel, while simultaneously decoupling the flow rates of the two channels, thereby improving the power generation performance and operational reliability of the air-cooled fuel cell.

Description

Technical Field

[0001] This invention relates to the field of air-cooled fuel cell technology, and in particular to an air-cooled fuel cell based on a series flow field and its thermal management method. Background Technology

[0002] Fuel cells are considered a highly efficient energy conversion technology that can directly convert the chemical energy stored in fuel into electrical and thermal energy through electrochemical reactions. To reduce size, mass, and complexity, small fuel cells typically employ air cooling for thermal management.

[0003] Traditional air-cooled fuel cells are mainly divided into two structures: open-cathode and closed-cathode. In open-cathode air-cooled stacks, the cooling air and the cathode reaction air share the same channel, causing interference between cooling and cathode reaction, making it difficult to simultaneously meet the heat dissipation and reaction requirements. In addition, the cathode inlet air temperature is relatively low, affecting the stack performance. Closed-cathode air-cooled stacks require two independent fans to supply air to the cooling channel and the cathode channel respectively. The system is large, heavy, and consumes a lot of power. The cathode inlet air temperature is also relatively low, which is not conducive to mobile applications such as drones and portable power supplies.

[0004] In the current technology, there is no air-cooled fuel cell structure that can achieve cooling and cathode flow channel air supply in series using a single fan, and precisely adjust the ratio of the two airflows. Therefore, there is an urgent need for a new type of air-cooled fuel cell to solve the problems of mutual interference between cooling and cathode reaction in traditional air-cooled fuel cell stacks, or the need for dual fan configurations and low cathode inlet air temperature.

[0005] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art. Summary of the Invention

[0006] The purpose of this invention is to provide an air-cooled fuel cell based on a series flow field, so as to enable a single fan to supply air to an independent cooling channel and a cathode reaction channel, thereby improving the power generation performance and operational reliability of the air-cooled fuel cell.

[0007] To achieve the above objectives, the present invention provides an air-cooled fuel cell based on a series flow field, comprising: The fuel cell stack has a mounting end face; A series flow field structure, integrated on the fuel cell stack, includes sequentially connected independent cooling channels, a flow distribution assembly, and a cathode reaction channel. Each independent cooling channel has an independent cooling channel inlet and an independent cooling channel outlet, both disposed on the mounting end face. Each cathode reaction channel has a cathode reaction channel inlet and a cathode reaction channel outlet, both disposed on the mounting end face. The flow distribution assembly is disposed outside the mounting end face and connects the independent cooling channel outlet to the cathode reaction channel inlet, thus enabling communication between the independent cooling channels and the cathode reaction channel. A fan is installed on the mounting end face and connected to the inlet of the independent cooling channel, supplying air to the independent cooling channel and the cathode reaction channel.

[0008] Optionally, the diversion assembly includes an inner tube, a sleeve, and an outer tube coaxially sleeved together. The sleeve is disposed between the inner tube and the outer tube. The inner tube and the sleeve are tightly fitted together, and the outer tube and the sleeve have a radial gap to form an annular gap.

[0009] Optionally, the inlet of the inner tube is connected to the outlet of the independent cooling channel, and the outlet of the inner tube is connected to the inlet of the cathode reaction channel; the outer tube has an annular outlet that connects the annular gap to the external environment.

[0010] Optionally, the inner tube has multiple inner tube holes on its sidewall, and these holes are arranged along the axial direction of the inner tube to form multiple rows of holes. That is, the multiple inner tube holes in each row of holes are aligned along the axial direction of the inner tube, and each row of holes is evenly spaced along the circumference of the inner tube, with the circumferential distance between adjacent rows of holes being greater than the width of a single inner tube hole. The sleeve has multiple sleeve holes on its sidewall, and the number, size, and location of the sleeve holes are adapted to the inner tube holes. When the sleeve is in contact with the inner tube, each sleeve hole corresponds one-to-one with each inner tube hole.

[0011] Optionally, the inner tube and the sleeve can rotate relative to each other, with a relative rotation angle α between the inner tube and the sleeve. By changing the relative rotation angle α between the inner tube and the sleeve, the inner tube hole on the inner tube and the sleeve hole on the sleeve can be gradually changed from being completely aligned to being completely misaligned. When the inner tube hole and the sleeve hole are perfectly aligned, part of the air from the independent cooling channel enters the cathode reaction channel through the inner tube, forming the main airflow. The other part passes through the overlapping portion of the inner tube hole and the sleeve hole into the annular gap and is discharged to the outside from the annular gap outlet, forming an air split. As the relative rotation angle α between the inner tube and the sleeve increases, the overlapping area of ​​the inner tube hole and the sleeve hole decreases, and the flow distribution ratio between the main airflow and the air split increases. When the inner tube hole and the sleeve hole are completely misaligned, all the air from the independent cooling channel enters the cathode reaction channel through the inner tube.

[0012] Optionally, the air-cooled fuel cell further includes: The control unit is located on the mounting end face and is electrically connected to the fan and the shunt assembly. A temperature sensor, located inside or on the surface of the fuel cell stack, is electrically connected to the control unit and is used to monitor the temperature of the fuel cell stack in real time and transmit the temperature data to the control unit. The control unit adjusts the fan speed and the relative rotation angle α between the inner tube and the sleeve in the flow distribution assembly based on the temperature data, so as to control the flow ratio of air in the independent cooling channel to air entering the cathode reaction channel from the independent cooling channel.

[0013] Optionally, the flow ratio of air in the independent cooling channel to air entering the cathode reaction channel from the independent cooling channel is controlled between 1:1 and 4:1.

[0014] Optionally, the diversion assembly further includes a drive motor, which is disposed on the mounting end face, and its motor shaft is connected to one end of the sleeve via a synchronous belt; the control unit is electrically connected to the drive motor in the diversion assembly; when the control unit detects that the relative rotation angle α between the inner tube and the sleeve in the diversion assembly needs to be adjusted, it sends a rotation command to the drive motor, and the motor shaft of the drive motor rotates, driving the sleeve to rotate relative to the inner tube via the synchronous belt; a photoelectric encoder is disposed on the motor shaft of the drive motor, and the photoelectric encoder is electrically connected to the control unit, which collects the actual rotation angle of the motor shaft of the drive motor in real time and sends it to the control unit as a feedback signal; the control unit dynamically adjusts the output of the drive motor according to the difference between the actual rotation angle and the target rotation angle, so as to realize closed-loop control of the relative rotation angle α between the inner tube and the sleeve.

[0015] Optionally, the air-cooled fuel cell further includes a common distribution cavity, which is located on at least one side of the fuel cell stack and covers part of the outer peripheral surface of the fuel cell stack; heating elements are attached to the periphery of the common distribution cavity, and the heat generated by the heating elements is conducted through the common distribution cavity to heat the air entering the independent cooling channel inlet; the heating elements are electrically connected to the control unit, and are powered on or off under the control of the control unit to achieve heating or stop heating.

[0016] Optionally, the independent cooling channel is provided with multiple fins, each of which extends from the wall of the independent cooling channel toward the center of the channel, and the height of the fins near the middle of the fuel cell stack is greater than the height of the fins near the two ends of the fuel cell stack.

[0017] To achieve the above objectives, the present invention also provides a thermal management method for an air-cooled fuel cell, applied to the aforementioned air-cooled fuel cell. This thermal management method includes: during the start-up preheating phase of the air-cooled fuel cell, the control unit controls the heating elements surrounding the common distribution chamber to begin heating, controls the fan to operate at full power, and adjusts the relative rotation angle α between the inner tube and the sleeve until the inner tube hole and the sleeve hole are completely misaligned, allowing all the air in the independent cooling channel to enter the cathode reaction channel; the air enters the independent cooling channel and absorbs heat from the heating elements surrounding the common distribution chamber, thereby serving as a heating medium to heat the independent cooling channel and the cathode reaction channel; when the temperature sensor detects that the fuel cell stack has reached its operating temperature, the start-up preheating phase ends, and the heating elements stop heating the air. During the operation of the air-cooled fuel cell, the control unit controls the fan to output an initial airflow based on the metering ratio requirements of the cathode reaction. The relative rotation angle α between the inner tube and the sleeve is initially maintained until the inner tube hole and the sleeve hole are completely misaligned. As the stack temperature rises, when the temperature sensor detects that the stack temperature exceeds a set threshold, the control unit increases the fan speed to increase the cooling airflow while decreasing the relative rotation angle α between the inner tube and the sleeve. This prevents all the large flow of cooling air from entering the cathode reaction channel, thus meeting the requirements of the cathode reaction. During this process, the control unit continuously and dynamically adjusts the fan and the relative rotation angle α between the inner tube and the sleeve until the stack stabilizes at the operating temperature.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: 1. By integrating the series flow field and single-fan air supply design, the dual-fan configuration and multi-combination cavity structure of the traditional closed-loop air-cooled fuel cell stack are eliminated, which significantly simplifies the system architecture, reduces volume, weight and power consumption. At the same time, the waste heat of the fuel cell stack itself is used to preheat the cathode air intake, and the temperature uniformity is optimized by gradient distribution fins, so as to achieve efficient recovery of waste heat. This effectively solves the problems of low cathode air intake temperature, uneven heat dissipation and energy waste, and greatly improves the power generation performance and thermal management efficiency of the fuel cell stack.

[0019] 2. The coaxial sleeve-type flow divider assembly achieves precise decoupling and stepless flow divider between cooling airflow and cathode reaction airflow. It can dynamically adjust the airflow distribution ratio according to load and temperature, completely eliminating the defects of mutual interference between cooling and reaction airflow in traditional air-cooled fuel cell stacks. Moreover, the flow divider assembly has a compact structure, stable operation, and rapid response, effectively improving the adaptability of the fuel cell stack to different operating conditions and long-term operational reliability. It is also more suitable for lightweight mobile application scenarios such as drones and portable power supplies. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the air-cooled fuel cell of the present invention; Figure 2 This is an exploded view of the shunt assembly of the air-cooled fuel cell of the present invention; Figure 3A This is a schematic diagram of the operation of the diversion assembly when the inner tube hole and the sleeve hole are completely misaligned according to an embodiment of the present invention. Figure 3B This is a schematic diagram of the operation of the diversion assembly when the inner tube hole and the sleeve hole are partially aligned according to an embodiment of the present invention; Figure 3C This is a schematic diagram of the operation of the diversion assembly when the inner tube hole and the sleeve hole are fully aligned, according to an embodiment of the present invention.

[0021] In the diagram: 1. Fuel cell stack; 101. Mounting end face; 2. Fan; 3. Flow distribution assembly; 4. Independent cooling channel; 401. Independent cooling channel inlet; 402. Independent cooling channel outlet; 5. Cathode reaction channel; 501. Cathode reaction channel inlet; 502. Cathode reaction channel outlet; 6. Control unit; 7. Temperature sensor; 8. Inner tube; 9. Sleeve; 10. Outer tube; 11. Annular gap; 111. Annular gap outlet; 12. Inner tube hole; 13. Sleeve hole; 14. Common distribution chamber. Detailed Implementation

[0022] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the air-cooled fuel cell based on a series flow field and its thermal management method proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clarify the illustration of the embodiments of this invention. Please refer to the drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0023] This invention provides an air-cooled fuel cell based on a series flow field, such as... Figure 1 As shown, the air-cooled fuel cell includes: a stack 1 having a mounting end face 101; and a series flow field structure integrated on the stack 1, including an independent cooling channel 4, a flow splitter assembly 3, and a cathode reaction channel 5 connected in sequence.

[0024] The independent cooling channel 4 has an independent cooling channel inlet 401 and an independent cooling channel outlet 402, both of which are disposed on the mounting end face 101. The independent cooling channel 4 extends from the independent cooling channel inlet 401 into the interior of the fuel cell stack 1, and then turns back to the independent cooling channel outlet 402, thus forming a U-shaped path through the fuel cell stack 1. The cathode reaction channel 5 has a cathode reaction channel inlet 501 and a cathode reaction channel outlet 502, both of which are disposed on the mounting end face 101. The cathode reaction channel 5 extends from the cathode reaction channel inlet 501 into the interior of the fuel cell stack 1, and then turns back to the cathode reaction channel outlet 502, thus forming a U-shaped path through the fuel cell stack 1. Inside the fuel cell stack 1, several electrode plates are disposed, and the cathode reaction channel 5 and the independent cooling channel 4 are respectively located on opposite sides of the same electrode plate.

[0025] The flow splitter 3 is disposed on the outside of the mounting end face 101 and directly connects the independent cooling channel outlet 402 and the cathode reaction channel inlet 501, so that the independent cooling channel 4 and the cathode reaction channel 5 are connected to form the series flow field structure.

[0026] The air-cooled fuel cell also includes a fan 2, which is installed on the mounting end face 101 and directly connected to the independent cooling channel inlet 401, for supplying air to the independent cooling channel 4 and the cathode reaction channel 5.

[0027] Furthermore, the independent cooling channel inlet 401 is sealed and connected to the air outlet of the fan 2. The independent cooling channel outlet 402 has a tapered structure, which is used to enhance the airflow velocity and guide the air to the diversion assembly 3.

[0028] The independent cooling channel 4 is equipped with multiple fins, each extending from the wall of the independent cooling channel 4 towards the center of the channel to increase the heat exchange area. The leading edge of the fins is designed with an arc to effectively reduce air resistance. The heights of the fins are not exactly the same; the fins near the two ends of the fuel cell stack 1 are shorter, while the fins near the middle of the fuel cell stack 1 are taller, thereby increasing heat dissipation in the middle of the fuel cell stack 1 and improving the overall temperature distribution uniformity of the fuel cell stack 1.

[0029] like Figure 2 As shown, the diversion assembly 3 includes an inner tube 8, a sleeve 9, and an outer tube 10 coaxially sleeved together. The sleeve 9 is disposed between the inner tube 8 and the outer tube 10, and the inner tube 8 and the sleeve 9 are tightly fitted together. There is a radial gap between the outer tube 10 and the sleeve 9 to form an annular gap 11. The sleeve 9 and the outer tube 10 are sealed at both ends of the annular gap 11, so that both ends of the annular gap 11 are closed.

[0030] The inlet of the inner tube 8 is directly connected to the outlet 402 of the independent cooling channel, and the outlet of the inner tube 8 is directly connected to the inlet 501 of the cathode reaction channel. The outer tube 10 has an annular outlet 111, which is connected to the annular gap 11 and directly connected to the external environment. Ambient air enters the independent cooling channel 4 from the inlet 401 via the fan 2 as cooling air, and then flows into the diversion assembly 3 from the outlet 402. Under the diversion action of the diversion assembly 3, a main airflow and a secondary airflow are formed. The main airflow enters the cathode reaction channel 5 from the inlet 501 via the inner tube 8 as cathode air, and is finally discharged to the outside from the outlet 502. The secondary airflow does not enter the cathode reaction channel 5, but instead enters the annular gap 11 and is directly discharged to the outside from the outlet 111.

[0031] Specifically, the inner tube 8 of the diversion assembly 3 has multiple inner tube holes 12 on its side wall. These multiple inner tube holes 12 are arranged along the axial direction of the inner tube 8 to form multiple rows of holes. That is, the multiple inner tube holes 12 contained in each row of holes are aligned along the axial direction of the inner tube 8. Each row of holes is evenly spaced along the circumference of the inner tube 8, and the circumferential distance between adjacent groups of holes is greater than the width of a single inner tube hole 12. The sleeve 9 has multiple sleeve holes 13 on its side wall. The number, size, and location of the sleeve holes 13 are adapted to the inner tube holes 12. When the sleeve 9 and the inner tube 8 are fitted together, each sleeve hole 13 corresponds one-to-one with each inner tube hole 12.

[0032] The inner tube 8 and the sleeve 9 are rotatable relative to each other, with a relative rotation angle α between them. By changing this relative rotation angle α, the inner tube hole 12 on the inner tube 8 and the sleeve hole 13 on the sleeve 9 can be gradually changed from being completely aligned to being completely misaligned. When the inner tube hole 12 and the sleeve hole 13 are completely aligned, as... Figure 3C As shown, part of the air from the independent cooling channel 4 enters the cathode reaction channel 5 through the inner tube 8, forming the main airflow path A. The other part passes through the inner tube 8, through the overlapping part of the inner tube hole 12 and the sleeve hole 13, into the annular gap 11, and is directly discharged to the outside from the annular gap outlet 111, forming the air diversion flow path B. Figure 3B As shown, with the increase of the relative rotation angle α between the inner tube and the sleeve, the overlapping area of ​​the inner tube hole 12 and the sleeve hole 13 gradually decreases, and less and less air from the independent cooling channel 4 enters the annular gap 11, that is, the flow distribution ratio between the main airflow and the split airflow gradually increases; until the inner tube hole 12 and the sleeve hole 13 are completely misaligned, as... Figure 3AAs shown, at this point, the air from the independent cooling channel 4 is no longer split, and all of it enters the cathode reaction channel 5 through the inner tube 8. Therefore, by controlling the relative rotation angle α between the inner tube and the sleeve, the flow distribution ratio between the main airflow and the split airflow can be continuously adjusted, thereby precisely regulating the flow ratio of air entering the cathode reaction channel 5 from the independent cooling channel 4.

[0033] Furthermore, the air-cooled fuel cell also includes: a control unit 6, disposed on the mounting end face 101; and a temperature sensor 7, disposed inside or on the surface of the stack 1, electrically connected to the control unit 6, for real-time monitoring of the temperature of the stack 1 and transmitting the temperature data to the control unit 6. The control unit 6 is also electrically connected to the fan 2 and the flow divider 3, respectively. Based on the temperature data, it adjusts the rotational speed of the fan 2 and the relative rotation angle α between the inner tube and the sleeve in the flow divider 3, controlling the flow ratio of air in the independent cooling channel 4 to air entering the cathode reaction channel 5 from the independent cooling channel 4 (i.e., the flow ratio of cooling air to cathode air) to dynamically switch between 1:1 and 4:1, so as to ensure the stability of the stack temperature while meeting the cathode reaction requirements.

[0034] Specifically, the diversion assembly 3 also includes a drive motor (not shown in the figure), which is mounted on the mounting end face 101. Its motor shaft is connected to one end of the sleeve 9 via a synchronous belt. The drive motor is also electrically connected to the control unit 6. When the control unit 6 detects that the relative rotation angle α between the inner tube and the sleeve in the diversion assembly 3 needs to be adjusted, it sends a rotation command to the drive motor. The drive motor starts, its motor shaft rotates, and it drives the sleeve 9 to rotate synchronously via the synchronous belt, while the inner tube 8 remains stationary, thereby achieving relative rotation between the sleeve 9 and the inner tube 8. A photoelectric encoder is mounted on the motor shaft of the drive motor. This photoelectric encoder is electrically connected to the control unit 6. When the control unit 6 sends a rotation command containing the target rotation angle to the drive motor, the photoelectric encoder collects the actual rotation angle of the motor shaft in real time and sends it as a feedback signal to the control unit 6. The control unit 6 dynamically adjusts the output of the drive motor based on the difference between the actual rotation angle and the target rotation angle, thereby achieving closed-loop control of the relative rotation angle α between the inner tube and the sleeve.

[0035] Furthermore, the air-cooled fuel cell also includes a common distribution chamber 14, such as... Figure 1As shown, the common distribution cavity 14 is located on at least one side of the fuel cell stack 1 and covers a portion of the outer peripheral surface of the fuel cell stack 1. A heating element is attached to the periphery of the common distribution cavity 14. The heat generated by the heating element is conducted through the common distribution cavity 14 to heat the air entering the independent cooling channel inlet 401 during the start-up preheating phase. The heating element is electrically connected to the control unit 6, and under the control of the control unit 6, it is powered on or off to achieve heating or stop heating.

[0036] Furthermore, this invention provides a thermal management method applied to the aforementioned air-cooled fuel cell. The following detailed description of this thermal management method is provided in conjunction with specific embodiments. In this embodiment, the number of hole groups is four. When each of the sleeve holes 13 is fully aligned with each of the inner tube holes 12, the relative rotation angle α between the inner tube and sleeve is defined as 0° (e.g., ...). Figure 3C ).

[0037] The thermal management method includes: during the start-up preheating phase of the air-cooled fuel cell, the control unit 6 controls the heating elements around the common distribution chamber 14 to begin heating, controls the fan 2 to operate at full power, and controls the sleeve 9 to rotate relative to the inner tube 8 in any circumferential direction, so that the relative rotation angle α between the inner tube and the sleeve is adjusted to 45°. At this time, the inner tube hole 12 and the sleeve hole 13 are completely misaligned (e.g., Figure 3A All air in the independent cooling channel 4 enters the cathode reaction channel 5, meaning the flow ratio of cooling air to cathode air is 1:1. During this start-up preheating stage, ambient air enters the independent cooling channel inlet 401 via fan 2, absorbs heat from the heating elements surrounding the common distribution chamber 14, and enters the independent cooling channel 4. After flowing out of the independent cooling channel outlet 402, it immediately enters the inner tube 8 of the diversion assembly 3, and then directly enters the cathode reaction channel inlet 501 without diversion, flows through the cathode reaction channel 5, and finally flows out of the cathode reaction channel outlet 502. Throughout this start-up preheating stage, air acts as the heating medium to heat the independent cooling channel 4 and the cathode reaction channel 5. When the temperature sensor 7 detects that the fuel cell stack 1 has reached its operating temperature, the start-up preheating stage ends, and the heating elements are de-energized to stop heating the air.

[0038] During the operation of the air-cooled fuel cell, the control unit 6, based on the metering ratio requirements of the cathode reaction, controls the fan 2 to initially output the initial airflow. The relative rotation angle α between the inner tube and the sleeve is initially maintained at 45°. All air from the independent cooling channel 4 still enters the cathode reaction channel 5, with a cooling air to cathode air flow ratio of 1:1. As heat accumulates in the fuel cell stack 1, its temperature begins to rise. When the temperature sensor 7 detects that the temperature of the fuel cell stack 1 exceeds a set threshold, the control unit 6 increases the speed of the fan 2 to increase the cooling airflow, while simultaneously decreasing the relative rotation angle α between the inner tube and the sleeve, for example, to 22.5°, so that half of the inner tube hole 12 is aligned with the sleeve hole 13 (e.g., ...). Figure 3B This design ensures that not all of the large volume of cooling air enters the cathode reaction channel 5, thus meeting the requirements of the cathode reaction. Throughout this operational phase, ambient air enters the independent cooling channel 4 via the fan 2 as a cooling medium, absorbing the waste heat generated by the fuel cell stack 1 and becoming heated. It then enters the inner tube 8 of the diversion assembly 3. After being diverted by the diversion assembly 3, a portion of the heated air (the main airflow) enters the cathode reaction channel 5 as a reactant to participate in the cathode electrochemical reaction for power generation, and is then discharged through the cathode reaction channel outlet 502. The other portion of air (the diverted airflow) passes through the overlapping portion of the inner tube hole 12 and the sleeve hole 13, enters the annular gap 11, and is then directly discharged. During this process, the control unit 6 continuously and dynamically adjusts the relative rotation angle α between the fan 2 and the inner tube-sleeve until the fuel cell stack 1 stabilizes at its operating temperature.

[0039] This invention enables a single fan to supply air to the independent cooling channel and the cathode reaction air channel sequentially through a series flow field. It also utilizes the heat generated by the fuel cell stack itself to increase the inlet temperature of the cathode reaction air, preheating the cathode intake air. Simultaneously, it decouples the flow rates of the independent cooling channel and the cathode reaction air channel through a coaxial sleeve-type flow distribution assembly. This solves common problems such as mutual interference between cooling and cathode reaction in traditional open-cathode air-cooled fuel cell stacks, the bulky configuration of two fans in traditional closed-cathode air-cooled fuel cell stacks, and the performance degradation of the fuel cell stack due to low cathode intake air temperature. This invention improves the power generation performance and operational reliability of air-cooled fuel cells.

[0040] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0041] In the description of this invention, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0042] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0044] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. An air-cooled fuel cell based on a series flow field, characterized in that, include: The fuel cell stack has a mounting end face; A series flow field structure, integrated on the fuel cell stack, includes sequentially connected independent cooling channels, a flow distribution assembly, and a cathode reaction channel. Each independent cooling channel has an independent cooling channel inlet and an independent cooling channel outlet, both disposed on the mounting end face. Each cathode reaction channel has a cathode reaction channel inlet and a cathode reaction channel outlet, both disposed on the mounting end face. The flow distribution assembly is disposed outside the mounting end face and connects the independent cooling channel outlet to the cathode reaction channel inlet, thus enabling communication between the independent cooling channels and the cathode reaction channel. A fan is installed on the mounting end face and connected to the inlet of the independent cooling channel, supplying air to the independent cooling channel and the cathode reaction channel.

2. The air-cooled fuel cell as described in claim 1, characterized in that, The diversion assembly includes an inner tube, a sleeve, and an outer tube that are coaxially sleeved together. The sleeve is disposed between the inner tube and the outer tube. The inner tube and the sleeve are tightly fitted together. The outer tube and the sleeve have a radial gap to form an annular gap. The inlet of the inner tube is connected to the outlet of the independent cooling channel, and the outlet of the inner tube is connected to the inlet of the cathode reaction channel; the outer tube has an annular outlet, which connects the annular gap to the external environment.

3. The air-cooled fuel cell as described in claim 2, characterized in that, The inner tube has multiple inner tube holes on its side wall. These holes are arranged along the axial direction of the inner tube to form multiple rows of holes. Each row of holes contains multiple inner tube holes aligned along the axial direction of the inner tube. Each row of holes is evenly spaced along the circumference of the inner tube, and the circumferential distance between adjacent rows of holes is greater than the width of a single inner tube hole. The sleeve has multiple sleeve holes on its side wall. The number, size, and location of the sleeve holes are adapted to the inner tube holes. When the sleeve is in contact with the inner tube, each sleeve hole corresponds to each inner tube hole.

4. The air-cooled fuel cell as described in claim 3, characterized in that, The inner tube and the sleeve can rotate relative to each other, and there is a relative rotation angle α between the inner tube and the sleeve. By changing the relative rotation angle α between the inner tube and the sleeve, the inner tube hole on the inner tube and the sleeve hole on the sleeve can be gradually changed from being completely aligned to being completely misaligned. When the inner tube hole and the sleeve hole are perfectly aligned, part of the air from the independent cooling channel enters the cathode reaction channel through the inner tube, forming the main airflow. The other part passes through the overlapping portion of the inner tube hole and the sleeve hole into the annular gap and is discharged to the outside from the annular gap outlet, forming an air split. As the relative rotation angle α between the inner tube and the sleeve increases, the overlapping area of ​​the inner tube hole and the sleeve hole decreases, and the flow distribution ratio between the main airflow and the air split increases. When the inner tube hole and the sleeve hole are completely misaligned, all the air from the independent cooling channel enters the cathode reaction channel through the inner tube.

5. The air-cooled fuel cell as described in claim 4, characterized in that, The air-cooled fuel cell also includes: The control unit is located on the mounting end face and is electrically connected to the fan and the shunt assembly. A temperature sensor, located inside or on the surface of the fuel cell stack, is electrically connected to the control unit and is used to monitor the temperature of the fuel cell stack in real time and transmit the temperature data to the control unit. The control unit adjusts the fan speed and the relative rotation angle α between the inner tube and the sleeve in the flow distribution assembly based on the temperature data, so as to control the flow ratio of air in the independent cooling channel to air entering the cathode reaction channel from the independent cooling channel.

6. The air-cooled fuel cell as described in claim 5, characterized in that, The air flow ratio between the independent cooling channel and the air entering the cathode reaction channel from the independent cooling channel is controlled between 1:1 and 4:

1.

7. The air-cooled fuel cell as described in claim 5, characterized in that, The diversion assembly also includes a drive motor, which is mounted on the mounting end face. Its motor shaft is connected to one end of the sleeve via a synchronous belt. The control unit is electrically connected to the drive motor in the diversion assembly. When the control unit detects that the relative rotation angle α between the inner tube and the sleeve in the diversion assembly needs to be adjusted, it sends a rotation command to the drive motor. The motor shaft of the drive motor rotates and drives the sleeve to rotate relative to the inner tube via the synchronous belt. A photoelectric encoder is mounted on the motor shaft of the drive motor. The photoelectric encoder is electrically connected to the control unit and collects the actual rotation angle of the motor shaft in real time and sends it as a feedback signal to the control unit. The control unit dynamically adjusts the output of the drive motor according to the difference between the actual rotation angle and the target rotation angle to achieve closed-loop control of the relative rotation angle α between the inner tube and the sleeve.

8. The air-cooled fuel cell as described in claim 5, characterized in that, The air-cooled fuel cell also includes a common distribution cavity, which is located on at least one side of the fuel cell stack and covers part of the outer peripheral surface of the fuel cell stack. A heating element is attached to the periphery of the common distribution cavity, and the heat generated by the heating element is conducted through the common distribution cavity to heat the air entering the independent cooling channel inlet. The heating element is electrically connected to the control unit and is powered on or off under the control of the control unit to achieve heating or stop heating.

9. The air-cooled fuel cell as described in claim 1, characterized in that, The independent cooling channel is provided with multiple fins, each of which extends from the wall of the independent cooling channel toward the center of the channel, and the height of the fins near the middle of the fuel cell stack is greater than the height of the fins near the two ends of the fuel cell stack.

10. A thermal management method for an air-cooled fuel cell, applied to the air-cooled fuel cell as described in any one of claims 1-9, characterized in that, The thermal management method includes: during the start-up preheating phase of the air-cooled fuel cell, the control unit controls the heating elements around the common distribution chamber to start heating, controls the fan to run at full power, and adjusts the relative rotation angle α between the inner tube and the sleeve until the inner tube hole and the sleeve hole are completely misaligned, so that all the air in the independent cooling channel enters the cathode reaction channel; the air enters the independent cooling channel and absorbs the heat from the heating elements around the common distribution chamber, thereby serving as a heating medium to heat the independent cooling channel and the cathode reaction channel; when the temperature sensor detects that the stack has reached the operating temperature, the start-up preheating phase ends, and the heating elements stop heating the air; During the operation of the air-cooled fuel cell, the control unit controls the fan to output an initial airflow based on the metering ratio requirements of the cathode reaction. The relative rotation angle α between the inner tube and the sleeve is initially maintained until the inner tube hole and the sleeve hole are completely misaligned. As the stack temperature rises, when the temperature sensor detects that the stack temperature exceeds a set threshold, the control unit increases the fan speed to increase the cooling airflow while decreasing the relative rotation angle α between the inner tube and the sleeve. This prevents all the large flow of cooling air from entering the cathode reaction channel, thus meeting the requirements of the cathode reaction. During this process, the control unit continuously and dynamically adjusts the fan and the relative rotation angle α between the inner tube and the sleeve until the stack stabilizes at the operating temperature.

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