Fuel cell stack structure that can operate stably in low temperature environments

Abstract

A fuel cell stack structure capable of stable operation in a low-temperature environment comprises a shell, a stack is arranged in the shell, a first air inlet channel is arranged between the top of the stack and the shell, a second air inlet channel is arranged between the bottom of the stack and the shell, an exhaust fan is arranged at the air outlet of the stack, and two baffles and two baffle rotation drive devices are arranged on the outside of the air outlet of the stack. The utility model respectively arranges the first air inlet channel and the second air inlet channel between the top and bottom of the stack and the shell, and the waste heat and exhaust gas of the stack reaction are returned through the baffles, so that the outside of the first end plate and the second end plate of the stack are surrounded by air with a higher temperature in a low-temperature environment, ensuring stable operation in a low-temperature environment. By arranging a blocking structure in some air grooves on the bipolar plates on both sides or making their cross-sectional area smaller, or changing the number and area of ​​the heat dissipation holes of the bipolar plates on both sides, the stable operation of the stack in a low-temperature environment is further improved.

Description

Technical Field

[0001] The utility model relates to the field of chemistry, in particular to a fuel cell, and in particular to a fuel cell stack structure which can stably operate in a low-temperature environment. Background Art

[0002] Proton exchange membrane fuel cells are devices that directly convert the chemical energy of hydrogen and oxygen in the air into electrical energy. They have the advantages of high energy conversion efficiency, no pollution, low noise, safety and reliability, etc., which have attracted widespread attention and have been widely used in many fields. The existing fuel cell structures are mainly divided into two categories: cathode open fuel cells and cathode closed fuel cells. Cathode closed fuel cells have special cooling channels, water pumps, radiators, cooling water tanks, etc. The system has good environmental adaptability and stability, but the cooling system greatly increases the complexity of the stack structure and control system. It is generally used in relatively large fuel cell systems, such as automotive, backup power, etc. Cathode open fuel cells, also known as air-cooled fuel cells in the industry, have a special structural design and inhale air through a fan. Air is not only used as the reaction gas of the fuel cell, but also can take away the heat generated by the reaction to cool the battery, combining air supply and system heat dissipation into one, simplifying the system, and is particularly suitable for applications that are sensitive to weight, such as portable fuel cells and drones. However, the stoichiometric ratio of the air flow on the cathode side of this type of battery is generally high, with more than ten times or even hundreds of times the stoichiometric ratio of air flowing through the battery, making this type of fuel cell greatly affected by the ambient temperature of use, especially in low-temperature environments. Due to the inhalation of a large amount of low-temperature air, the fuel cell system dissipates too much heat and the fuel cell cannot maintain a suitable operating temperature. When the operating temperature of the fuel cell stack is too low, the moisture generated on the air side of the fuel cell cannot be discharged from the cathode in time, causing flooding of the cathode, resulting in performance degradation or even reverse polarity, and even ice on the cathode side, making it impossible for the fuel cell to operate for a long time at low temperatures.

[0003] The stack consists of two end plates and some single chips in the middle connected in series. Each single chip includes a bipolar plate, MEA (membrane electrode), etc. During operation, the single chips close to the two end plates are close to the external environment, resulting in uneven temperatures on both sides, which can easily cause performance degradation. The single chips in the stack are connected in series. If a single chip has a problem, the output of the entire stack will be affected, so it is necessary to improve the performance reliability of the single chips close to the two end plates.

[0004] Secondly, the bipolar plates of the cathode open stack are composed of graphite plates or metal sheets. The graphite plates use the same air grooves for heat dissipation and air supply, while the metal sheets use different air grooves for heat dissipation and air supply. Sometimes, in order to increase the heat dissipation efficiency and reaction uniformity, some heat dissipation holes are made on the surface of the air grooves. However, in the prior art, the air grooves and heat dissipation holes increase the heat dissipation effect, which further leads to uneven temperatures on both sides of the single piece near the two end plates. In the prior art, the performance of the single piece near the end plate is ensured by insulating or heating the end plate, but this method will increase the complexity of system accessories and control, as well as increase the volume of the system. Summary of the invention

[0005] The purpose of the utility model is to provide a fuel cell stack structure that can operate stably in a low-temperature environment. The fuel cell stack structure that can operate stably in a low-temperature environment is to solve the technical problem of uneven temperature on both sides of a single piece close to the end plate in the prior art.

[0006] The utility model discloses a fuel cell stack structure that can operate stably in a low-temperature environment, including a shell, in which a fuel cell stack is arranged, a first air inlet channel is arranged between the top of the fuel cell stack and the shell, a second air inlet channel is arranged between the bottom of the fuel cell stack and the shell, an air inlet is arranged at one end of the fuel cell stack, and an air outlet is arranged at the other end of the fuel cell stack, the air inlet of the fuel cell stack is arranged opposite to the closed end of the shell and is connected with the first air inlet channel and the second air inlet channel, an exhaust fan is arranged at the air outlet of the fuel cell stack, two baffles and two baffle rotation driving devices are arranged on the outer side of the air outlet of the fuel cell stack, the positions of the two baffles respectively correspond to the positions of the first air inlet channel and the second air inlet channel, the power output ends of the two baffle rotation driving devices are respectively connected to the two baffles, and the control end of the baffle rotation driving device is connected to a controller.

[0007] Furthermore, the baffle rotation driving device includes a motor, the output shaft of the motor is connected to the baffle via a rotating shaft, and the axial direction of the rotating shaft is perpendicular to the axial direction of the gas outlet of the fuel cell stack.

[0008] Furthermore, the battery stack includes a first end plate, a second end plate and a plurality of single sheets arranged between the first end plate and the second end plate, each of the single sheets includes a bipolar plate, and each of the bipolar plates is provided with a plurality of air grooves.

[0009] Furthermore, the bipolar plate is composed of a wavy metal sheet, which forms a plurality of air grooves with different opening directions. A sealing structure is provided in some of the air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate. The sealing structure is provided at one end close to the air inlet of the fuel cell stack, or extends from one end of the air groove to the other end to seal the entire air groove.

[0010] Furthermore, the number of air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate are respectively smaller than the number of air grooves on any other bipolar plates.

[0011] Furthermore, the sum of the cross-sectional areas of the air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate is respectively smaller than the sum of the cross-sectional areas of the air grooves on any other bipolar plates.

[0012] Furthermore, a plurality of heat dissipation holes are provided on the side walls of the air grooves of any bipolar plate.

[0013] Furthermore, the number of heat dissipation holes on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate is respectively less than the number of heat dissipation holes on any other bipolar plate.

[0014] Furthermore, the total area of ​​the heat dissipation holes on the bipolar plate adjacent to the first end plate and the total area of ​​the heat dissipation holes on the bipolar plate adjacent to the second end plate are respectively smaller than the total area of ​​the heat dissipation holes on any other bipolar plates.

[0015] Furthermore, a heating device is provided in the shell and outside the air inlet of the fuel cell stack.

[0016] Compared with the prior art, the utility model has a positive and obvious effect. The utility model sets a first air inlet channel and a second air inlet channel between the top and bottom of the battery stack and the shell respectively, and the waste heat and exhaust gas of the battery stack reaction are returned through the baffle, so that the first end plate and the second end plate of the battery stack are surrounded by high temperature air outside in a low temperature environment, and the temperature difference between the two sides of the single plate adjacent to the first end plate and the second end plate becomes smaller, ensuring stable operation in a low temperature environment.

[0017] In addition, by providing a sealing structure in some of the air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate, or by designing and calculating to ensure that the sum of the cross-sectional areas of the intake air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate is respectively smaller than the sum of the cross-sectional areas of the air grooves on any of the other bipolar plates, or by changing the number and area of ​​the heat dissipation holes on the air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate, the stable operation of the battery stack in a low temperature environment is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of a fuel cell stack structure that can operate stably in a low-temperature environment according to the utility model.

[0019] Figure 2It is a schematic diagram of the internal structure of a fuel cell stack in a fuel cell stack structure that can operate stably in a low-temperature environment according to the utility model.

[0020] Figure 3 It is a schematic diagram of a bipolar plate composed of graphite plates in a fuel cell stack structure that can operate stably in a low-temperature environment according to the utility model.

[0021] Figure 4 It is a schematic diagram of a first type of air groove on a bipolar plate made of metal sheets in a fuel cell stack structure that can operate stably in a low-temperature environment according to the utility model.

[0022] Figure 5 It is a schematic diagram of a second type of air groove on a bipolar plate made of metal sheets in a fuel cell stack structure that can operate stably in a low-temperature environment according to the utility model.

[0023] Figure 6 It is a schematic diagram showing that the air grooves of the bipolar plates in the fuel cell stack structure capable of stably operating in a low temperature environment according to the utility model are blocked.

[0024] Figure 7 It is a schematic diagram of heat dissipation holes of a bipolar plate in a fuel cell stack structure that can stably operate in a low-temperature environment according to the utility model.

[0025] Figure 8 This is a schematic diagram of a fuel cell stack structure capable of stably operating in a low-temperature environment according to the utility model, in which the front end of an air groove is blocked. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with an embodiment, but the present invention is not limited to the embodiment. Any similar structure and similar changes of the present invention should be included in the protection scope of the present invention. The use of directions such as up, down, front, back, left, and right in the present invention is only for the convenience of clear description and is not a limitation on the technical solution of the present invention.

[0027] like Figure 1-Figure 8As shown, a fuel cell stack structure of the utility model that can operate stably in a low-temperature environment includes a shell 1, a stack 2 is arranged in the shell 1, a first air inlet channel 3 is arranged between the top of the stack 2 and the shell 1, a second air inlet channel 4 is arranged between the bottom of the stack 2 and the shell 1, an air inlet 5 is arranged at one end of the stack 2, and an air outlet 6 is arranged at the other end of the stack 2, the air inlet 5 of the stack 2 is arranged opposite to the closed end of the shell 1 and is connected with the first air inlet channel 3 and the second air inlet channel 4, an exhaust fan 7 is arranged at the air outlet 6 of the stack 2, two baffles 8 and two baffle rotation driving devices (not shown in the figure) are arranged on the outside of the air outlet 6 of the stack 2, the positions of the two baffles 8 correspond to the positions of the first air inlet channel 3 and the second air inlet channel 4 respectively, the power output ends of the two baffle rotation driving devices are respectively connected to the two baffles 8, and the control end of the baffle rotation driving device is connected to a controller.

[0028] According to the control of the controller's operating program algorithm, when the ambient temperature is very high, or the intake temperature is high and no adjustment is required, the motor drives the two baffles 8 to lie flat, and air enters the fuel cell stack 2 from the first air inlet channel 3 and the second air inlet channel 4. A small portion of air oxygen enters the fuel cell stack 2 and is consumed by the fuel cell stack 2, and as a reactant, it passes through the gas diffusion layer into the cathode of the fuel cell, undergoes an electrochemical reaction, and generates water. In addition, most of the air undergoes heat exchange to extract the waste heat generated in the fuel cell stack 2, taking away the heat of the fuel cell stack 2, and then is discharged from the air outlet 6 of the fuel cell stack 2 through the exhaust fan.

[0029] In a low-temperature environment, temperature sensors are provided at various positions such as the external environment, the stack air intake, and the stack exhaust. After the fuel cell is successfully started at low temperature, the temperature sensors are used to detect the ambient temperature, the stack air intake temperature, the stack temperature, and the stack exhaust temperature in real time. The angles of the two baffles 8 are adjusted in real time by the motor, so that part or all of the hot air discharged from the stack 2 is changed in direction by the two baffles 8, enters the first air inlet channel 3 and the second air inlet channel 4 of the fuel cell, and merges with the fresh air, and then is sucked into the stack 2. By adjusting the positions of the two baffles 8, the mixing ratio of fresh air intake and hot air discharged from the stack 2 can be achieved, thereby controlling the temperature of the stack 2 air intake and achieving stable operation of the stack 2 in a low-temperature environment. Different stacks 2, different power outputs, and different ambient temperatures will have different requirements for the mixing ratio of hot air and cold air, and the rotation angle of the baffle 8 is different, which can be adjusted according to actual conditions.

[0030] In the utility model, a first air inlet channel 3 and a second air inlet channel 4 are respectively arranged between the top and bottom of the fuel cell stack 2 and the shell 1. The residual heat and exhaust gas of the reaction of the fuel cell stack 2 are returned through the baffle 8, so that the outside of the first end plate 9 and the second end plate 10 of the fuel cell stack 2 are surrounded by air with higher temperature in a low-temperature environment, and the temperature difference on both sides of the single piece adjacent to the first end plate 9 and the second end plate 10 becomes smaller, thereby ensuring stable operation in a low-temperature environment.

[0031] Furthermore, the baffle rotation driving device includes a motor, the output shaft of the motor is connected to the baffle 8 via a rotating shaft (not shown in the figure), and the axial direction of the rotating shaft is perpendicular to the axial direction of the gas outlet 6 of the fuel cell stack 2.

[0032] Furthermore, the battery stack 2 includes a first end plate 9, a second end plate 10 and a plurality of single sheets arranged between the first end plate 9 and the second end plate 10, each of the single sheets includes a bipolar plate 11, and each of the bipolar plates 11 is provided with a plurality of air grooves 12.

[0033] Furthermore, the bipolar plate 11 is composed of a wavy metal sheet, which forms a plurality of air grooves 12 with different opening directions. A sealing structure 16 is provided in some of the air grooves 12 on the bipolar plate 11 adjacent to the first end plate 9 and the bipolar plate 11 adjacent to the second end plate 10. The sealing structure 16 is provided at one end of the air inlet 5 close to the fuel cell stack 2, or extends from one end of the air groove 12 to the other end to seal the entire air groove 12.

[0034] By blocking the air groove 12, the cold air entering is reduced, and the temperature difference between the two sides of the bipolar plates 11 is reduced. Figure 8 As shown, when the blocking structure 16 is disposed at one end of the air inlet 5 close to the battery stack 2, air cannot enter the air groove 12 from the front end, but air can enter from the remaining unblocked air grooves 12 to be heated, and then enter the blocked air grooves 12 from the rear end in the opposite direction to maintain the temperature.

[0035] Specifically, the blocking structure can be realized during processing on the bipolar plate, or by adding an external sealing material.

[0036] Furthermore, the number of air grooves 12 on the bipolar plate 11 adjacent to the first end plate 9 and the bipolar plate 11 adjacent to the second end plate 10 is respectively less than the number of air grooves 12 on any other bipolar plate 11 .

[0037] Furthermore, the sum of the cross-sectional areas of the air grooves 12 on the bipolar plate 11 adjacent to the first end plate 9 and the bipolar plate 11 adjacent to the second end plate 10 is respectively smaller than the sum of the cross-sectional areas of the air grooves 12 on any other bipolar plates 11 .

[0038] Furthermore, a plurality of heat dissipation holes 13 are provided on the side walls of the air groove 12 of any bipolar plate 11 .

[0039] Furthermore, the number of heat dissipation holes 13 on the bipolar plate 11 adjacent to the first end plate 9 and the bipolar plate 11 adjacent to the second end plate 10 is respectively less than the number of heat dissipation holes 13 on any other bipolar plate 11 .

[0040] Furthermore, the total area of ​​the heat dissipation holes 13 on the bipolar plate 11 adjacent to the first end plate 9 and the total area of ​​the heat dissipation holes 13 on the bipolar plate 11 adjacent to the second end plate 10 are respectively smaller than the total area of ​​the heat dissipation holes 13 on any other bipolar plate 11 .

[0041] By reducing, eliminating or blocking the air grooves 12 or heat dissipation holes 13 on the bipolar plates 11 adjacent to the first end plate 9 and the second end plate 10, the entry of cold air is reduced, heat dissipation is reduced, and the temperature difference between the two monolithic bipolar plates 11 is reduced, thereby improving the operating stability of the fuel cell stack in a low-temperature environment.

[0042] Furthermore, a heating device 14 is provided in the shell 1 and outside the air inlet of the battery stack 2. The heating device can be a heating mesh, a heating plate with a hollow structure, or other porous heating devices, which can preheat the intake air of the battery stack during the startup of the battery stack to ensure the normal low-temperature startup of the battery stack. The control of the heating device 14 depends on the ambient temperature, the intake temperature of the battery stack, the internal temperature of the battery stack, and the exhaust temperature of the battery stack. The heating device can be located at different positions of the shell according to different designs, and all should be included in the protection scope of the present utility model.

[0043] Specifically, the housing 1, the exhaust fan 7, the baffle rotation drive device, the first end plate 9, the air groove 12, the heat dissipation holes 13, the heating device 14, etc. in this embodiment all adopt the known solutions in the prior art, which are well known to those skilled in the art and will not be described in detail here. The single chip also includes a membrane electrode 15 and other structures.

Claims

1. A fuel cell stack structure capable of stably operating in a low temperature environment, characterized in that: It includes a shell, in which a battery stack is arranged, a first air inlet channel is arranged between the top of the battery stack and the shell, a second air inlet channel is arranged between the bottom of the battery stack and the shell, an air inlet is arranged at one end of the battery stack, and an air outlet is arranged at the other end of the battery stack, the air inlet of the battery stack is arranged opposite to the closed end of the shell and is connected with the first air inlet channel and the second air inlet channel, an exhaust fan is arranged at the air outlet of the battery stack, two baffles and two baffle rotation driving devices are arranged on the outside of the air outlet of the battery stack, the positions of the two baffles correspond to the positions of the first air inlet channel and the second air inlet channel respectively, the power output ends of the two baffle rotation driving devices are connected to the two baffles respectively, and the control end of the baffle rotation driving device is connected to a controller.

2. A fuel cell stack structure capable of stably operating in a low temperature environment according to claim 1, characterized in that: The battery stack includes a first end plate, a second end plate and a plurality of single sheets arranged between the first end plate and the second end plate, each of the single sheets includes a bipolar plate, and each of the bipolar plates is provided with a plurality of air grooves.

3. A fuel cell stack structure capable of stably operating in a low temperature environment according to claim 2, characterized in that: The bipolar plate is composed of a wavy metal sheet, which is formed with a plurality of air grooves with different opening directions. A sealing structure is provided in some of the air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate. The sealing structure is provided at one end close to the air inlet of the fuel cell stack, or extends from one end of the air groove to the other end to seal the entire air groove.

4. A fuel cell stack structure capable of stably operating in a low temperature environment according to claim 2, characterized in that: The number of air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate are respectively smaller than the number of air grooves on any other bipolar plates.

5. The fuel cell stack structure capable of stably operating in a low temperature environment according to claim 2, characterized in that: The sum of cross-sectional areas of the air grooves on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate is respectively smaller than the sum of cross-sectional areas of the air grooves on any other bipolar plates.

6. A fuel cell stack structure capable of stably operating in a low temperature environment according to claim 2, characterized in that: A plurality of heat dissipation holes are arranged on the side wall of the air groove of any bipolar plate, and the number of heat dissipation holes on the bipolar plate adjacent to the first end plate and the bipolar plate adjacent to the second end plate is respectively less than the number of heat dissipation holes on any other bipolar plate.

7. The fuel cell stack structure capable of stably operating in a low temperature environment according to claim 2, characterized in that: The total area of ​​the heat dissipation holes on the bipolar plate adjacent to the first end plate and the total area of ​​the heat dissipation holes on the bipolar plate adjacent to the second end plate are respectively smaller than the total area of ​​the heat dissipation holes on any other bipolar plate.

8. The fuel cell stack structure capable of stably operating in a low temperature environment according to claim 1, characterized in that: A heating device is arranged in the shell and outside the air inlet of the fuel cell stack.

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