An air-cooled fuel cell air circulation system

Abstract

This invention discloses an air-cooled fuel cell air circulation system, including a fuel cell stack and an air circulation assembly. The fuel cell stack has an air outlet and an air inlet. The air outlet is connected to an air inlet channel, and the air inlet is connected to an air outlet channel. The air circulation assembly includes an air circulation pipe with an inlet end and an outlet end. The inlet end is located in the air outlet channel, and the outlet end is located in the air inlet channel. During operation of the air-cooled fuel cell air circulation system, air flows in through the air inlet channel, passes through the fuel cell stack, and flows out through the air outlet channel, carrying moisture and becoming humidified air. This humidified air then enters the air inlet channel through the air circulation pipe, mixes with dry air, and enters the fuel cell stack, improving the humidity inside the fuel cell stack during operation and enhancing its performance.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to an air-cooled fuel cell air circulation system. Background Technology

[0002] Fuel cells are devices that directly convert the chemical energy of fuel into electrical energy, offering advantages such as high efficiency, low noise, and zero pollution. Fuel cells typically require multiple individual cells to be assembled into a stack via series connection. The main components include bipolar plates, membrane electrode assemblies (MEAs), end plates, and fasteners. Air-cooled fuel cells, in particular, use airflow for temperature control and lack cooling channels on their bipolar plates. Therefore, air-cooled fuel cells offer advantages such as simple structure, low cost, and high reliability.

[0003] Existing air-cooled fuel cells require cooling, so their bipolar plates have relatively large airflow channels. Excess air enters the fuel cell stack, thus achieving cooling and temperature control for the fuel cell.

[0004] However, in the early stages of fuel cell stack operation, internal humidity has a significant impact on fuel cell performance, requiring a certain level of humidity to ensure high proton conductivity of the proton exchange membrane. Current solutions typically involve adding a humidifier, but humidifiers are expensive, significantly increasing the manufacturing cost of air-cooled fuel cells. Summary of the Invention

[0005] The purpose of this invention is to provide an air-cooled fuel cell air circulation system to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0006] The technical solution adopted to solve the above-mentioned technical problems is as follows:

[0007] This invention provides an air-cooled fuel cell air circulation system, including a battery stack and an air circulation assembly. The battery stack is provided with an air outlet and an air inlet. The air outlet is connected to an air inlet channel, and the air inlet is connected to an air outlet channel. The air circulation assembly includes an air circulation pipe with an air inlet end and an air outlet end. The air inlet end is disposed in the air outlet channel, and the air outlet end is disposed in the air inlet channel.

[0008] The beneficial effects of this invention are:

[0009] When the air circulation system of an air-cooled fuel cell is running, air flows in through the air intake channel, passes through the inside of the fuel cell stack, and flows out through the air outlet channel. The air carries moisture and becomes humid air. The humid air enters the air intake channel through the air circulation pipe, mixes with dry air, and enters the inside of the fuel cell stack. This improves the humidity inside the fuel cell stack during operation and enhances the performance of the fuel cell stack.

[0010] As a further improvement to the above technical solution, the air circulation pipe is connected to a flow regulating device, which can adjust the humidity passing through the air circulation pipe according to different states of the battery stack, so as to better achieve the water and heat balance inside the battery electrodes.

[0011] As a further improvement to the above technical solution, the flow regulating device includes a circulating air pump. The circulating air pump can both promote the entry of humidified air into the air intake channel and regulate the circulation volume of humidified air.

[0012] As a further improvement to the above technical solution, the air-cooled fuel cell air circulation system also includes a stack air extraction device. The stack air extraction device is connected to the air inlet channel. The power of the stack air extraction device is greater than the power of the circulation pump, so that the gas velocity in the air circulation pipe is greater than the gas velocity in the air outlet channel, and the gas velocity in the air circulation channel is greater than the gas velocity at the air outlet, thereby generating a pressure difference to facilitate the intake and circulation of humid air.

[0013] As a further improvement to the above technical solution, the air circulation duct includes a curved section above the battery stack. The curved section arches upward, and condensate flows out of the air circulation duct under the action of gravity, reducing the accumulation of condensate in the air circulation duct and avoiding affecting the circulation of humid air.

[0014] As a further improvement to the above technical solution, the air circulation duct includes a first section, a second section, a third section, and a fourth section, which are connected sequentially. The second and third sections are positioned above the battery stack and are inclined vertically. The projected surfaces of the second and third sections in the front-to-back direction are inverted V-shaped. The first section extends into the air intake channel, and the fourth section extends into the air outlet channel. Condensate can be discharged promptly along the second and third sections without clogging the air circulation duct.

[0015] As a further improvement to the above technical solution, a rounded corner structure is provided at the connection between the first pipe section and the second pipe section, and a rounded corner structure is provided at the connection between the third pipe section and the fourth pipe section to prevent condensate from accumulating and clogging the air circulation pipe.

[0016] As a further improvement to the above technical solution, the air circulation duct includes an air outlet section disposed within the air intake channel. The air outlet section has multiple air outlets and is curved within a plane perpendicular to the air intake direction of the air intake channel. This ensures that the air outlets are evenly distributed within the plane perpendicular to the air intake direction of the air intake channel, allowing the humid air exiting the air outlets to mix evenly with the dry air entering the air intake channel before entering the battery stack.

[0017] As a further improvement to the above technical solution, the air outlet pipe section is annular, and the air outlet hole penetrates the air outlet pipe section along the air intake direction of the air intake channel. Multiple air outlet holes are arranged in annular intervals on the air outlet pipe section. The annular shape and the air outlet hole penetrating the air outlet pipe section provide sufficient space for the entry flow of dry air, while allowing the dry air and humid air to mix fully.

[0018] As a further improvement to the above technical solution, the air circulation duct includes an air inlet section disposed within the air outlet duct, the air inlet section being connected to a funnel-shaped air intake, the air intake facing the air outlet to facilitate the intake of humid air. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0020] Figure 1 This invention provides an air-cooled fuel cell air circulation system, and a schematic diagram of the outlet pipe section structure of one embodiment is shown.

[0021] Figure 2 This invention provides an air-cooled fuel cell air circulation system, and a schematic diagram of the outlet pipe section structure of one embodiment is shown.

[0022] Figure 3 This is a schematic diagram of an embodiment of an air-cooled fuel cell air circulation system provided by the present invention, wherein the two arrows represent upward and downward directions, respectively.

[0023] Figure label:

[0024] Battery stack 100, air inlet channel 110, air outlet channel 120, air circulation pipe 200, first pipe section 201, second pipe section 202, third pipe section 203, fourth pipe section 204, air outlet pipe section 210, air inlet pipe section 220, air outlet 211, flow regulating device 300, battery stack air extraction device 400. Detailed Implementation

[0025] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0026] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this 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. Therefore, they should not be construed as limiting this invention.

[0027] In the description of this invention, if there are words such as "several", they mean one or more, "multiple" means two or more, "greater than", "less than", "exceeding" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself.

[0028] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0029] Existing air-cooled fuel cells, due to cooling requirements, feature relatively large airflow channels in their bipolar plates. Excess air entering the fuel cell stack achieves cooling and temperature control. However, in the initial stages of fuel cell stack operation, internal humidity is crucial for maintaining the hydrothermal balance within the electrode assembly. This significantly impacts the efficiency, performance, safety, and lifespan of the fuel cell system. The primary function of humidifying the incoming dry air is to improve the mass transfer efficiency and proton conductivity of the reactant gases, enhance system efficiency, ensure operational stability, and extend battery life. To achieve this humidification effect, this invention incorporates an air circulation component that recirculates the humidified air from inside the fuel cell stack back to the stack's air inlet. This solves the problems of difficult humidity control and high humidifier costs associated with existing air-cooled fuel cell stacks, thereby improving the stack performance during operation.

[0030] Reference Figures 1 to 3 The present invention provides an air-cooled fuel cell air circulation system according to the following embodiments:

[0031] In some embodiments, an air-cooled fuel cell air circulation system includes a fuel cell stack 100 with an air outlet and an air inlet. The air outlet is connected to an air inlet channel 110, and the air inlet is connected to an air outlet channel 120. The air circulation assembly includes an air circulation duct 200, which has an inlet end and an outlet end. The inlet end is located in the air outlet channel 120, and the outlet end is located in the air inlet channel 110. During operation of the air-cooled fuel cell air circulation system, under the action of the fuel cell stack extraction device 400, air flows into the fuel cell stack 100 from the air inlet channel 110, participates in the reaction as a cathode reaction gas, and then flows out from the air outlet channel 120, carrying moisture. Simultaneously, as the humid air is discharged, it is circulated back into the air inlet channel 110 through the air circulation duct 200 by the circulation pump, mixes with dry air, and enters the fuel cell stack 100, improving the humidity inside the fuel cell stack 100 during operation and enhancing its internal performance.

[0032] The circulating air pump is one type of flow regulation device 300. The flow regulation device 300 can employ various regulating valves, such as electric or manual regulating valves. It can adjust the humidity through the air circulation pipe 200 according to different states of the battery stack 100, such as aging of the battery stack 100, to better achieve the water-thermal balance inside the battery electrodes. The circulating air pump can both promote the entry of humidified air into the air intake pipe 110 and regulate the amount of humidified air circulating. The circulating air pump can also be automatically controlled and regulated.

[0033] In some other embodiments, the flow regulating device 300 may not be provided, and the fuel cell pumping device 400 may be used directly to allow humidified air to enter the air intake channel 110 through the air circulation pipe 200, but the amount of circulating air cannot be controlled.

[0034] Furthermore, when the power of the fuel cell stack extraction device 400 is greater than the power of the circulating extraction pump, the gas velocity in the air circulation pipe 200 is greater than the air outlet velocity in the air outlet 120, which in turn makes the gas velocity in the air circulation channel greater than the air outlet velocity, creating a pressure difference that facilitates the intake and circulation of humidified air.

[0035] To ensure timely drainage of condensate, the air circulation duct 200 includes a first section 201, a second section 202, a third section 203, and a fourth section 204, which are connected sequentially. The second and third sections 202 are positioned above the battery stack 100 and are inclined vertically. Their projected surfaces in the front-to-back direction form an inverted V-shape. The first section 201 extends into the air intake channel 110, and the fourth section 204 extends into the air outlet channel 120. Condensate can be promptly drained along the second and third sections 202 without clogging the air circulation duct 200.

[0036] In order to better drain condensate, the connection between the first pipe section 201 and the second pipe section 202 is equipped with a rounded corner structure, and the connection between the third pipe section 203 and the fourth pipe section 204 is equipped with a rounded corner structure to prevent condensate from accumulating and clogging the air circulation pipe 200.

[0037] In other embodiments, the air circulation duct 200 includes a curved section located beside the battery stack 100. The curved section arches outward. When the curved section is located above the battery stack 100, the curved section arches upward, and condensate flows out of the air circulation duct 200 under the action of gravity, reducing the accumulation of condensate in the air circulation duct 200 and avoiding affecting the circulation of humid air.

[0038] Furthermore, due to the relatively large diameter of the air inlet channel 110, and considering that multiple gas channels are provided within the battery stack 100, the inlet ends of these multiple gas channels are connected to the air inlet channel 110, and the outlet ends of these multiple gas channels are connected to the air outlet channel 120. During the reaction inside the battery stack 100, the air from the air inlet channel 110 is separately introduced into the multiple gas channels. The rapid and uniform mixing of dry and humid air within the air inlet channel 110 better maintains the hydrothermal balance within the battery electrodes.

[0039] Therefore, an air outlet pipe section 210 is also provided. The air outlet pipe section 210 is located within the air intake channel 110. The air outlet pipe section 210 and the first pipe section 201 refer to the same pipe section. The air outlet pipe section 210 can be referred to as Figure 3 As shown, a straight pipe extends into the air intake channel 110, and the outlet pipe section 210 is provided with multiple air outlet holes 211 facing the air intake. The first pipe section 201 can also be arranged in a ring shape.

[0040] In other embodiments, the vent pipe section 210 is provided with multiple vent holes 211, and the vent pipe section 210 is curved in a plane perpendicular to the air intake direction of the air intake channel 110. This allows the vent holes 211 to be evenly distributed in the plane perpendicular to the air intake direction of the air intake channel 110, so that the humid air exiting from the vent holes 211 mixes evenly with the dry air entering from the air intake channel 110 before entering the battery stack 100. The multiple vent holes 211 are evenly distributed in a ring at intervals in the vent pipe section 210, resulting in more uniform mixing of dry air and humid air.

[0041] Furthermore, to facilitate the intake of humid air, an air intake pipe section 220 is provided. The air intake pipe section 220 is located inside the air outlet passage 120. The air intake pipe section 220 is connected to a funnel-shaped air inlet, which faces the air outlet to facilitate the intake of humid air.

[0042] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. An air-cooled fuel cell air circulation system, characterized in that, include: The battery stack (100) is provided with an air outlet and an air inlet, the air outlet being connected to an air inlet channel (110) and the air inlet being connected to an air outlet channel (120). An air circulation assembly includes an air circulation duct (200) having an inlet end and an outlet end, the inlet end being disposed in the air outlet passage (120) and the outlet end being disposed in the air inlet passage (110). The air circulation duct (200) includes an air outlet section (210) disposed within the air intake duct (110). The air outlet section (210) is provided with a plurality of air outlet holes (211). The air outlet section (210) is curved in a plane perpendicular to the air intake direction of the air intake duct (110). The air circulation duct (200) includes a curved section disposed above the battery stack (100). The curved section arches upward. The air circulation duct (200) includes an air intake section (220) disposed within the air outlet duct (120). The air intake section (220) is connected to a horn-shaped air inlet, which faces the air outlet.

2. The air-cooled fuel cell air circulation system according to claim 1, characterized in that: The air circulation duct (200) is connected to a flow regulating device (300).

3. The air circulation system for a wind-cooled fuel cell according to claim 2, characterized in that: The flow regulating device (300) includes a circulating air pump.

4. The air-cooled fuel cell air circulation system according to claim 3, characterized in that: The air circulation system of the air-cooled fuel cell also includes a stack extraction device (400), which is connected to the air intake channel (110). The power of the stack extraction device (400) is greater than the power of the circulation pump, so that the flow velocity of the gas in the air circulation pipe (200) is greater than the flow velocity in the air outlet channel (120).

5. The air circulation system for a wind-cooled fuel cell according to claim 1, characterized in that: The air circulation duct (200) includes a first pipe section (201), a second pipe section (202), a third pipe section (203), and a fourth pipe section (204). The first pipe section (201), the second pipe section (202), the third pipe section (203), and the fourth pipe section (204) are connected in sequence. The second pipe section (202) and the third pipe section (203) are located above the battery stack (100). The second pipe section (202) and the third pipe section (203) are arranged at an upward and downward inclination. The projection surface of the second pipe section (202) and the third pipe section (203) in the front-back direction is inverted V shape. The first pipe section (201) extends into the air intake channel (110), and the fourth pipe section (204) extends into the air outlet channel (120).

6. The air circulation system for a wind-cooled fuel cell according to claim 5, characterized in that: The connection between the first pipe segment (201) and the second pipe segment (202) is provided with a rounded corner structure, and the connection between the third pipe segment (203) and the fourth pipe segment (204) is provided with a rounded corner structure.

7. The air-cooled fuel cell air circulation system according to claim 1, characterized in that: The air outlet section (210) is annular, and the air outlet (211) passes through the air outlet section (210) along the air intake direction of the air intake channel (110). A plurality of air outlets (211) are arranged in annular intervals on the air outlet section (210).

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