A fuel cell system suitable for high-altitude operations

Abstract

The present invention provides a fuel cell system suitable for high-altitude operations, belonging to the field of fuel cell technology, and solving the problem of low energy conversion efficiency of existing devices when used in high-altitude operations. The system includes an oxygen separator, an air compressor, a regulating valve, a circulation device, a fuel cell stack, and a controller. The oxygen outlet of the oxygen separator is connected to the first input of the regulating valve via the air compressor, and its nitrogen outlet is connected to the second input of the regulating valve; the air inlet of the fuel cell stack is connected to the output of the regulating valve, and the exhaust air outlet is connected to the air inlet of the fuel cell stack via the circulation device. After startup, the controller first heats the oxygen separator to quickly produce oxygen, then starts the air compressor and controls the regulating valve to a matching opening according to the current atmospheric pressure. The circulation device is then started. After the exhaust air pressure reaches a set value, the second input of the regulating valve is closed to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure. This system is suitable for energy applications in a variety of scenarios.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell system suitable for high-altitude operations. Background Art

[0002] A fuel cell system is a device that continuously converts the chemical energy of a continuously supplied fuel and oxidant into electrical energy. It typically consists of a fuel cell stack and peripheral components such as hydrogen, air, and cooling equipment. The stack further includes a proton exchange membrane, catalyst layer, gas diffusion layer, and bipolar plates. Because the theoretical voltage of a single cell is 1.23V, high power output is typically achieved by connecting hundreds of cells in parallel.

[0003] Currently, fuel cell systems are primarily used in hydrogen fuel cell vehicles (FCVs), a new energy vehicle with broad development and application prospects, offering numerous advantages such as short refueling times and extended driving range.

[0004] Fuel cell systems are used in high-altitude environments, such as aircraft. Because the air is thin at high altitudes, a very high compression ratio is required to compress the air to the pressure required for the fuel cell reaction, which results in very low fuel cell efficiency. Oxygen partial pressure is a key parameter in the reaction within the fuel cell, and 79% of the nitrogen in the air does not participate in the reaction. Summary of the Invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a fuel cell system suitable for high-altitude operations, so as to solve the problem of low energy conversion efficiency of existing devices when used in high-altitude operations.

[0006] On the one hand, an embodiment of the present invention provides a fuel cell system suitable for high-altitude operations, comprising an oxygen separation device (3), an air compressor (2), a regulating valve (9), a circulation device (8), a fuel cell stack (5), and a controller (10); wherein,

[0007] The oxygen outlet of the oxygen separation device (3) is connected to the first input end of the regulating valve (9) via the air compressor (2), and the nitrogen outlet is connected to the second input end of the regulating valve (9); the air inlet of the fuel cell stack (5) is connected to the output end of the regulating valve (9), and the air tail gas outlet is connected to the air inlet thereof via the circulation device (8);

[0008] The controller (10) further comprises:

[0009] The data acquisition unit is used to obtain the current atmospheric pressure and exhaust gas pressure and send them to the data processing and control unit;

[0010] The data processing and control unit is used to heat the oxygen separation device (3) to a set temperature to quickly prepare oxygen after startup, then start the air compressor (2), and control the regulating valve (9) to reach a set opening according to the atmospheric pressure at the current moment, and then start the circulation device (8). After the air tail gas pressure of the fuel cell stack (5) reaches a set value, the second input end of the regulating valve (9) is closed to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure.

[0011] The controller (10) is used to heat the oxygen separation device (3) to quickly produce oxygen after startup, then start the air compressor (2), and control the regulating valve (9) to reach a matching opening according to the current atmospheric pressure, and then start the circulation device (8). After the air tail gas pressure of the fuel cell stack (5) reaches a set value, the second input end of the regulating valve (9) is closed to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure. The data processing and control unit also executes the following program:

[0012] According to the air flow meter (1) collected at each time t within the preset period i Instantaneous air flow rate q ti , combined with the preset inlet pressure P of the stack and the exhaust pressure P1 of the air in the circulation device (8), the speed V of the air compressor (2) is obtained.

[0013] V=f(A,B,P,P1)

[0014] A=(q t1 +…+q tn ) / (t n -t1)

[0015] B=(q t1 -A) 2 +…+(q tn -A) 2

[0016] Where, i=1,…,n, f() is the fitting function;

[0017] Adjust the operating state of the air compressor (2) to the above-mentioned speed.

[0018] The beneficial effects of the above technical solution are as follows: a fuel cell system suitable for high-altitude operations (aircraft, etc.) is provided, which can still ensure high reaction efficiency even when the oxygen pressure on the air side of the stack is low. For example, under normal circumstances, the pressure on the air side of the fuel cell system is 200kPa, and the oxygen partial pressure is approximately 42kPa. Therefore, at high altitudes, it is only necessary to compress the separated oxygen to 42kPa, which is equivalent to a conventional fuel cell system and can effectively reduce the power of the air compressor.

[0019] Based on the further improvement of the above system, the high-transmittance membrane in the oxygen separation device (3) is made of a barium-containing perovskite oxide material.

[0020] Furthermore, the data acquisition unit further comprises:

[0021] A temperature sensor is provided inside the oxygen separation device (3) and is used to obtain the ambient temperature inside the oxygen separation device (3);

[0022] An air flow meter (1) is provided at the inlet of the oxygen separation device (3) and is used to obtain the instantaneous flow rate of the air at the current moment;

[0023] An atmospheric pressure sensor, provided outside the battery stack (5), for obtaining the atmospheric pressure at the current moment;

[0024] The gas pressure sensor (7) is arranged inside the inlet pipe of the circulation device (8) and is used to obtain the pressure of the exhaust gas of the air entering the circulation device (8).

[0025] Furthermore, the data processing and control unit executes the following program:

[0026] After receiving the user's start command, obtain the current atmospheric pressure;

[0027] Controlling the oxygen separation device (3) to perform heating, during the heating process, monitoring the temperature inside the oxygen separation device (3) in real time, and after the temperature reaches a set temperature, introducing air to perform oxygen separation;

[0028] Starting the air compressor (2) and controlling the regulating valve (9) to reach a set opening according to the current atmospheric pressure;

[0029] The circulation device (8) is started, and the pressure of the exhaust air entering the circulation device (8) is monitored. When the exhaust air pressure reaches a set value, the second input end of the regulating valve (9) is closed, and pure oxygen is introduced through the first input end of the regulating valve (9) to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure.

[0030] Furthermore, the fuel cell system further comprises a sealing valve (4); wherein,

[0031] One end of the sealing valve (4) is suspended, the other end is connected to the nitrogen outlet of the oxygen separation device (3), and the control end is connected to the output end of the controller (10).

[0032] Furthermore, the data processing and control unit also executes the following program:

[0033] After closing the second input end of the regulating valve (9), the sealing valve (4) is opened to continuously deliver the nitrogen.

[0034] Furthermore, the fuel cell system further includes a drain and exhaust valve (6); wherein,

[0035] One path of the exhaust air outlet of the fuel cell stack (5) is connected to the air inlet thereof through the circulation device (8), and the other path is connected to the drain and exhaust valve (6);

[0036] The control end of the drain and exhaust valve (6) is connected to the output end of the controller (10).

[0037] Furthermore, the data processing and control unit also executes the following program:

[0038] Identify whether the drain and exhaust valve (6) is open. If so, proceed to the next step. Otherwise, close the second input terminal of the regulating valve (9) to replenish pure oxygen to the fuel cell stack (5);

[0039] The regulating valve (9) is controlled to reach a set opening to supplement the nitrogen and oxygen mixed gas to the fuel cell stack (5).

[0040] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0041] 1. The barium oxide nanoparticles precipitated on the surface of barium-containing perovskite oxides are highly active for oxygen activation. These particles are also active sites for oxygen exchange reactions. Therefore, they can be used to prepare high-temperature oxygen-permeable membranes to achieve efficient separation of oxygen from the air, making them suitable for fuel cell system applications in various scenarios.

[0042] 2. In a pure oxygen environment, the oxidizing property is too strong. In order to increase the life of components, a certain amount of nitrogen is added.

[0043] 3. When the drain and exhaust valve is opened, some nitrogen will be discharged. In order to ensure the volume ratio of oxygen, a certain amount of nitrogen and oxygen mixing ratio should be added at this time.

[0044] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0046] Figure 1 A schematic diagram of the fuel cell system composition of embodiment 1 suitable for high-altitude operations is shown;

[0047] Figure 2A schematic diagram of the fuel cell system composition of Example 2 suitable for high-altitude operations is shown;

[0048] Figure 3 A schematic diagram of the control principle of the fuel cell system of Example 2 is shown.

[0049] Reference numerals:

[0050] 1-air flow meter; 2-air compressor; 3-oxygen separator; 4-sealing valve;

[0051] 5-cell stack; 6-drain and exhaust valve; 7-gas pressure sensor; 8-circulation device; 9-regulating valve; 10-controller. DETAILED DESCRIPTION

[0052] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0053] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0054] Example 1

[0055] One embodiment of the present invention discloses a fuel cell system suitable for high-altitude operations, such as Figure 1 As shown, it includes an oxygen separation device 3, an air compressor 2, a regulating valve 9, a circulation device 8, a fuel cell stack 5 and a controller 10.

[0056] Among them, the oxygen outlet of the oxygen separation device 3 is connected to the input end 1 of the regulating valve 9 through the air compressor 2, and its nitrogen outlet is connected to the input end 2 of the regulating valve 9; the air inlet of the fuel cell stack 5 is connected to the output end of the regulating valve 9, and the air exhaust outlet is connected to the air inlet through the circulation device 8.

[0057] The controller 10 is used to heat the oxygen separation device 3 to quickly prepare oxygen after startup, then start the air compressor 2, and control the regulating valve 9 to reach a matching opening according to the current atmospheric pressure. Then, the circulation device 8 is started. After the air exhaust pressure of the fuel cell stack 5 reaches the set value, the second input terminal of the regulating valve 9 is closed to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure.

[0058] It should be noted that the engine also includes a fuel gas control branch and a coolant control branch, which can be seen in patent CN202011171825.1, etc. All of them use existing equipment and need no elaboration, which can be understood by those skilled in the art.

[0059] In practice, due to the thinness of air at high altitudes, existing fuel cell systems require a very high compression ratio to compress the air to the pressure required for the fuel cell reaction. This results in very low fuel cell system efficiency. Oxygen partial pressure is a key parameter for fuel cell reactions, and 79% of nitrogen in the air does not participate in the reaction. Therefore, the oxygen separation device 3 separates nitrogen from oxygen in the atmosphere and compresses the oxygen separately, thus ensuring the efficiency of the fuel cell system at high altitudes remains at a normal level.

[0060] Compared with the existing technology, this embodiment provides a fuel cell system suitable for high-altitude operations (aircraft, etc.), which can still ensure high reaction efficiency even when the oxygen pressure on the air side of the stack is low. For example, under normal circumstances, the pressure on the air side of the fuel cell system is 200kPa, and the oxygen partial pressure is approximately 42kPa. Therefore, at high altitudes, it is only necessary to compress the separated oxygen to 42kPa, which is equivalent to a conventional fuel cell system and can effectively reduce the power of the air compressor.

[0061] Example 2

[0062] Based on Example 1, an improvement was made, in which the high-permeability membrane in the oxygen separation device 3 is made of a barium-containing perovskite oxide. The barium oxide nanoparticles precipitated on the surface of the barium-containing perovskite oxide are highly active for oxygen activation and serve as active sites for oxygen exchange reactions. Therefore, they can be used to prepare high-temperature oxygen-permeable membranes, achieving efficient separation of oxygen from the air and suitable for fuel cell system applications in a variety of scenarios.

[0063] Oxygen separation devices are typically gas devices equipped with high-temperature oxygen-permeable membranes made of novel materials. These membranes can separate air into oxygen and nitrogen at high temperatures, such as 700°C using a high-permeability membrane containing barium perovskite oxide. For details on the structure of oxygen separation devices, see patents CN201380039222.8, CN201920525750.9, and CN202120461920.9.

[0064] Preferably, the output end of the controller 10 is connected to the control ends of the oxygen separation device 3 , the air compressor 2 , the regulating valve 9 , and the circulation device 8 .

[0065] Preferably, the controller 10 further includes a data acquisition unit and a data processing and control unit which are connected in sequence.

[0066] The data acquisition unit is used to obtain the current atmospheric pressure and air exhaust pressure and send them to the data processing and control unit.

[0067] The data processing and control unit is used to heat the oxygen separation device 3 to the set temperature to quickly prepare oxygen after startup, then start the air compressor 2, and control the regulating valve 9 to reach the set opening according to the current atmospheric pressure. Then, the circulation device 8 is started. After the air exhaust pressure of the fuel cell stack 5 reaches the set value, the second input terminal of the regulating valve 9 is closed to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure.

[0068] Preferably, the data acquisition unit further includes a temperature sensor, an air flow meter 1 , an atmospheric pressure sensor, and a gas pressure sensor 7 .

[0069] The temperature sensor is provided inside the oxygen separation device 3 and is used to obtain the ambient temperature inside the oxygen separation device 3 .

[0070] The air flow meter 1 is provided at the inlet of the oxygen separation device 3 and is used to obtain the instantaneous flow of air at the current moment.

[0071] The atmospheric pressure sensor is provided outside the fuel cell stack 5 and is used to obtain the current atmospheric pressure.

[0072] The gas pressure sensor 7 is provided inside the inlet pipe of the circulation device 8 and is used to obtain the pressure of the exhaust gas entering the circulation device 8 .

[0073] Preferably, the data processing and control unit executes the following program:

[0074] S1. After receiving the user's start command, obtain the current atmospheric pressure;

[0075] S2. Control the oxygen separation device 3 to perform heating. During the heating process, the temperature within the oxygen separation device 3 is monitored in real time. After it reaches the set temperature, air is introduced to separate the oxygen.

[0076] S3 starts the air compressor 2, according to the current moment of atmospheric pressure control valve 9 reaches the set opening;

[0077] S4. Start the circulation device 8 and monitor the exhaust air pressure entering the circulation device 8. When the exhaust air pressure reaches the set value, close the second input of the regulating valve 9 and introduce pure oxygen through the first input of the regulating valve 9 to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure.

[0078] The control principle of the controller is as follows Figure 3 shown.

[0079] Preferably, the fuel cell system further comprises a sealing valve 4, such as Figure 2 One end of the sealing valve 4 is suspended, the other end is connected to the nitrogen outlet of the oxygen separation device 3 , and the control end is connected to the output end of the controller 10 .

[0080] Preferably, the data processing and control unit further executes the following program:

[0081] S5. After closing the second input end of the regulating valve 9, open the sealing valve 4 to continuously deliver the nitrogen.

[0082] Preferably, the fuel cell system further includes a drain and exhaust valve 6. The exhaust gas outlet of the fuel cell stack 5 is connected to the air inlet via a circulation device 8 on one side and to the drain and exhaust valve 6 on the other side. The control end of the drain and exhaust valve 6 is connected to the output end of the controller 10.

[0083] Preferably, the data processing and control unit further executes the following program:

[0084] S6. Identify whether the drain and exhaust valve 6 is open. If so, proceed to the next step. Otherwise, close the second input terminal of the regulating valve 9 to supplement pure oxygen to the stack 5.

[0085] S7. Control the regulating valve 9 to reach a set opening to replenish the nitrogen and oxygen mixture to the fuel cell stack 5.

[0086] Preferably, the fuel cell system further comprises an air filter, wherein the air filter is arranged at the inlet of the oxygen separation device 3 .

[0087] Preferably, the set temperature is 600-800°C.

[0088] Preferably, the data processing and control unit further executes the following program:

[0089] S8. According to the air flow meter 1 collected at each time t within the preset period i Instantaneous air flow rate q ti , combined with the preset intake pressure P of the fuel cell stack and the exhaust pressure P1 of the air in the circulation device 8, the speed V of the air compressor 2 is obtained.

[0090] V=f(A,B,P,P1)

[0091] A=(q t1 +…+q tn ) / (t n -t1)

[0092] B=(q t1 -A) 2 +…+(q tn -A) 2

[0093] Where i = 1, ..., n, A and B are intermediate variables, and f() is the fitting function obtained by laboratory calibration;

[0094] S9. Adjust the operating state of the air compressor 2 to the above speed.

[0095] Compared with Example 1, the device provided in this embodiment has the following beneficial effects:

[0096] 1. The barium oxide nanoparticles precipitated on the surface of barium-containing perovskite oxides are highly active for oxygen activation. These particles are also active sites for oxygen exchange reactions. Therefore, they can be used to prepare high-temperature oxygen-permeable membranes to achieve efficient separation of oxygen from the air, making them suitable for fuel cell system applications in various scenarios.

[0097] 2. In a pure oxygen environment, the oxidizing property is too strong. In order to increase the life of components, a certain amount of nitrogen is added.

[0098] 3. When the drain and exhaust valve is opened, some nitrogen will be discharged. In order to ensure the volume ratio of oxygen, a certain amount of nitrogen and oxygen mixing ratio should be added at this time.

[0099] While various embodiments of the present disclosure have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements over the prior art, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell system suitable for high-altitude operations, characterized in that: It comprises an oxygen separation device (3), an air compressor (2), a regulating valve (9), a circulation device (8), a fuel cell stack (5) and a controller (10); wherein, The oxygen outlet of the oxygen separation device is connected to the first input end of the regulating valve (9) via the air compressor (2), and the nitrogen outlet is connected to the second input end of the regulating valve (9); the air inlet of the fuel cell stack (5) is connected to the output end of the regulating valve (9), and the air tail gas outlet is connected to the air inlet thereof via the circulation device (8); The controller (10) is used to heat the oxygen separation device (3) to quickly produce oxygen after startup, then start the air compressor (2), and control the regulating valve (9) to reach a matching opening according to the current atmospheric pressure, and then start the circulation device (8). After the air tail gas pressure of the fuel cell stack (5) reaches a set value, close the second input end of the regulating valve (9) to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure; The controller (10) further comprises: The data acquisition unit is used to obtain the current atmospheric pressure and exhaust gas pressure and send them to the data processing and control unit; The data processing and control unit is used to heat the oxygen separation device (3) to a set temperature to quickly produce oxygen after startup, then start the air compressor (2), and control the regulating valve (9) to reach a set opening according to the current atmospheric pressure, and then start the circulation device (8). After the air tail gas pressure of the fuel cell stack (5) reaches a set value, close the second input end of the regulating valve (9) to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure; The data processing and control unit executes the following procedures: According to the air flow meter (1) collected at each time t within the preset period i Instantaneous air flow rate q ti , combined with the preset intake pressure P of the fuel cell stack (5) and the exhaust pressure P1 of the air in the circulation device (8), the speed V of the air compressor (2) is obtained. V=f(A,B,P,P1) A=(q t1 +…+q tn ) / (t n -t1) B=(q t1 -A) 2 +…+(q tn -A) 2 Where, i=1,…,n, f() is the fitting function; Adjust the operating state of the air compressor (2) to the above-mentioned speed.

2. The fuel cell system suitable for high-altitude operations according to claim 1, characterized in that: The high-transmittance membrane in the oxygen separation device (3) is made of a barium-containing perovskite oxide material.

3. The fuel cell system suitable for high-altitude operations according to claim 1, characterized in that: The data acquisition unit further comprises: A temperature sensor is provided inside the oxygen separation device (3) and is used to obtain the ambient temperature inside the oxygen separation device (3); An air flow meter (1) is provided at the inlet of the oxygen separation device (3) and is used to obtain the instantaneous flow rate of the air at the current moment; An atmospheric pressure sensor, provided outside the battery stack (5), for obtaining the atmospheric pressure at the current moment; The gas pressure sensor (7) is arranged inside the inlet pipe of the circulation device (8) and is used to obtain the pressure of the exhaust gas of the air entering the circulation device (8).

4. The fuel cell system suitable for high-altitude operations according to claim 3, characterized in that: The data processing and control unit executes the following procedures: After receiving the user's start command, obtain the current atmospheric pressure; Controlling the oxygen separation device (3) to perform heating, during the heating process, monitoring the temperature inside the oxygen separation device (3) in real time, and after the temperature reaches a set temperature, introducing air to perform oxygen separation; Starting the air compressor (2) and controlling the regulating valve (9) to reach a set opening according to the current atmospheric pressure; The circulation device (8) is started, and the pressure of the exhaust air entering the circulation device (8) is monitored. When the exhaust air pressure reaches a set value, the second input end of the regulating valve (9) is closed, and pure oxygen is introduced through the first input end of the regulating valve (9) to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set partial pressure.

5. The fuel cell system suitable for high-altitude operations according to claim 4, characterized in that: Also includes a sealing valve (4); wherein, One end of the sealing valve (4) is suspended, the other end is connected to the nitrogen outlet of the oxygen separation device (3), and the control end is connected to the output end of the controller (10).

6. The fuel cell system suitable for high-altitude operations according to claim 5, characterized in that: The data processing and control unit also executes the following program: After closing the second input end of the regulating valve (9), the sealing valve (4) is opened to continuously deliver the nitrogen.

7. The fuel cell system suitable for high-altitude operations according to claim 6, characterized in that: It also includes a drain and exhaust valve (6); wherein, One path of the exhaust air outlet of the fuel cell stack (5) is connected to the air inlet thereof through the circulation device (8), and the other path is connected to the drain and exhaust valve (6); The control end of the drain and exhaust valve (6) is connected to the output end of the controller (10).

8. The fuel cell system suitable for high-altitude operations according to claim 7, characterized in that: The data processing and control unit also executes the following program: Identify whether the drain and exhaust valve (6) is open. If so, proceed to the next step. Otherwise, close the second input terminal of the regulating valve (9) to replenish pure oxygen to the fuel cell stack (5); The regulating valve (9) is controlled to reach a set opening to supplement the nitrogen and oxygen mixed gas to the fuel cell stack (5).

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