A method for controlling oxygen supply in a fuel cell system

Abstract

This invention discloses an oxygen supply control method for a fuel cell system. The method includes the following steps: acquiring the current altitude and ambient pressure; calculating the current oxygen content based on the ambient pressure; comparing the current oxygen content X1 with a set target oxygen content X2; and monitoring airflow to ensure that the oxygen supply is continuously increasing. This invention dynamically adjusts the air supply based on the relationship between altitude and oxygen content to maintain a real-time and appropriate oxygen supply, solving problems such as fixed oxygen supply, low energy efficiency, and insufficient accuracy in existing technologies, thereby improving the system's performance, efficiency, and stability.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell systems, and specifically relates to a method for controlling the oxygen supply of a fuel cell system. Background Technology

[0002] In the field of fuel cell systems, oxygen supply is crucial to system performance. Traditional fuel cell systems typically employ a fixed oxygen supply scheme, which cannot be dynamically adjusted according to environmental conditions (such as altitude).

[0003] There are some shortcomings of the existing technology that need to be addressed. For example: (1) Traditional fuel cell systems usually use a fixed oxygen supply, which cannot be dynamically adjusted according to environmental conditions (such as altitude), which may lead to insufficient or excessive oxygen supply. (2) Existing systems may have low energy efficiency in terms of oxygen supply, failing to make full use of oxygen resources and affecting the overall efficiency of the system. (3) Current oxygen supply control methods may lack precise adjustment capabilities and cannot monitor and adjust the oxygen supply in real time to meet system requirements.

[0004] Therefore, it is crucial to develop a method that can dynamically adjust oxygen supply based on real-time environmental conditions in order to improve system efficiency, stability, and energy utilization. Summary of the Invention

[0005] This invention provides an oxygen supply control method for a fuel cell system, proposing the following solutions: (1) Dynamic adjustment of oxygen supply: By dynamically adjusting the oxygen supply flow rate or pressure according to the relationship between altitude and oxygen content, the system can always obtain an appropriate oxygen supply. (2) Improved energy efficiency: This invention can effectively improve the energy efficiency of the system by adjusting the oxygen supply according to real-time demand, avoiding over-supply or under-supply, thereby improving the overall efficiency of the system. (3) Precise control: By monitoring the altitude and oxygen content in real time, the oxygen supply can be precisely controlled to ensure stable system operation and avoid energy waste and performance degradation. Overall, this invention provides an innovative oxygen supply control method for fuel cell systems, dynamically adjusting the air supply according to the relationship between altitude and oxygen content to maintain an appropriate real-time oxygen supply, solving the problems of fixed oxygen supply, low energy efficiency, and insufficient precision in the prior art, thereby improving the system's performance, efficiency, and stability.

[0006] The technical solution of this invention is as follows:

[0007] The control flow of an oxygen supply control method for a fuel cell system is as follows: Figure 1 .

[0008] A method for controlling oxygen supply in a fuel cell system includes the following steps:

[0009] S1: Obtain current altitude and environmental pressure

[0010] S2: Calculate the current oxygen content based on ambient pressure.

[0011] S3: Compare the current oxygen content X1 with the set target oxygen content X2 (oxygen content under standard atmospheric pressure).

[0012] If the current oxygen content is lower than the target oxygen content, the infeed water temperature T1 is greater than or equal to the target temperature T2, and the difference between the fuel cell system output voltage and the target voltage VΔ under the current operating conditions is in the range of 2V to 3V, then the speed of the air compressor will be increased by 10% to 30% to increase the oxygen flow rate; the opening of the back pressure valve will be reduced to 5% to 15% to reduce the back pressure of the system and promote the flow of oxygen.

[0013] If the current oxygen supply reaches or exceeds the target oxygen content, the oxygen supply control parameters will not be adjusted, and the current altitude and air pressure will be continuously monitored.

[0014] S4: Monitor airflow rate to ensure oxygen supply is continuously increasing. Under current operating conditions, the difference VΔ between the fuel cell system output voltage and the target voltage is less than 0.8V, and the single-cell voltage variance is less than 50, indicating sufficient oxygen supply and good system operation and performance. Stop adjusting the control parameters of the oxygen supply system, such as air metering ratio, air compressor speed, and back pressure valve opening. If the conditions of the fuel cell system output voltage difference VΔ being within the range of 0.1V to 0.8V and the single-cell voltage variance being less than 50 are not met, return to S3 and increase the air compressor speed by 10% to 30% to increase oxygen flow; reduce the back pressure valve opening to 5% to 15% to reduce system back pressure and promote oxygen flow.

[0015] Preferably, altitude and air pressure data, as well as target oxygen content, are collected in real time to adapt to environmental changes. Throughout the process, the stability and reliability of the oxygen supply process are monitored to ensure that the fuel cell system can operate stably at high altitudes and achieve the expected results.

[0016] Preferably, atmospheric pressure is affected by various factors, including altitude, climate conditions, and weather changes. Generally, atmospheric pressure at sea level under standard atmospheric conditions is 101325 Pascals (Pa), and it gradually decreases with increasing altitude. Specific atmospheric pressure values ​​will vary depending on local conditions and can be obtained using environmental pressure sensors.

[0017] Preferably, the voltage difference VΔ = target voltage - fuel cell system output voltage;

[0018] The following is a formula for calculating the current oxygen content based on altitude and air pressure data:

[0019] Calculate atmospheric pressure: Atmospheric pressure = air pressure data

[0020] Calculate the partial pressure of oxygen (assuming the partial pressure of water vapor is zero): According to the law of partial pressures, PO₂ = PX, where P is 101325 Pa and X is the mole fraction of oxygen in the atmosphere, approximately 20.95%.

[0021] Calculate oxygen content: Oxygen content = Oxygen partial pressure / Total atmospheric pressure

[0022] Among them, oxygen partial pressure refers to the partial pressure of oxygen in the current gas mixture, and total atmospheric pressure refers to one standard atmosphere, which is 101.325 kPa.

[0023] Preferably, such as Figure 2 This is a schematic diagram of the oxygen supply subsystem. Air typically passes through an air filter before entering the system to remove impurities and particulate matter, protecting the fuel cell system from contamination. A flow meter provides real-time feedback on the air flow rate before it enters the air compressor. The air needs to be compressed by the air compressor to increase the oxygen concentration and delivery efficiency. The compressed air then passes through an air humidifier to increase its humidity, and finally, the air distribution system directs it to the oxidant side of the fuel cell stack, ensuring each unit receives a sufficient oxygen supply.

[0024] The oxygen supply system of this invention includes an air filter, a flow meter, an air compressor, an intercooler, a humidifier, a fuel cell stack, a back pressure valve, a hydrogen-air mixing pipe, and a silencer. The air filter, flow meter, air compressor, and intercooler are connected in sequence and then connected to the dry air inlet of the humidifier. The dry air outlet of the humidifier is connected to the air inlet of the fuel cell stack, and the air outlet of the fuel cell stack is connected to the humidified air inlet of the humidifier. The humidified air outlet is connected in sequence to the back pressure valve, the hydrogen-air mixing pipe, and the silencer. The hydrogen-air mixing pipe is also connected to a hydrogen exhaust pipe.

[0025] In the above system, the air compressor is controlled by an air compressor controller.

[0026] In the above system, an air pressure sensor and a shut-off valve are also installed on the pipe between the dry air outlet of the humidifier and the air inlet of the fuel cell stack.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] (1) Dynamically adjust oxygen supply: dynamically adjust oxygen supply based on altitude and oxygen content.

[0029] (2) Real-time monitoring and adjustment: By monitoring environmental conditions in real time, the system can adjust the oxygen supply in a timely manner to maintain an appropriate oxygen supply, so as to ensure the optimal performance of the system under different operating conditions.

[0030] (3) Improve system efficiency: Improve the energy efficiency and overall performance of fuel cell system by precisely controlling oxygen supply. Attached Figure Description

[0031] Figure 1 A control flow diagram for an oxygen supply control method in a fuel cell system;

[0032] Figure 2 A schematic diagram of the oxygen supply subsystem for a fuel cell.

[0033] The components shown in the diagram are as follows: 1. Air filter, 2. Flow meter, 3. Air compressor, 4. Intercooler, 5. Humidifier, 6. Fuel cell stack, 7. Air pressure sensor, 8. Back pressure valve, 9. Hydrogen-air mixing pipe, 10. Silencer. Detailed Implementation

[0034] Example 1

[0035] like Figure 2 This embodiment provides an oxygen supply system, which includes an air filter 1, a flow meter 2, an air compressor 3, an intercooler 4, a humidifier 5, a fuel cell stack 6, a back pressure valve 8, a hydrogen-air mixing pipe 9, and a silencer 10. The air filter 1, flow meter 2, air compressor 3, and intercooler 4 are sequentially connected and then connected to the dry air inlet of the humidifier 5. The dry air outlet of the humidifier 5 is connected to the air inlet of the fuel cell stack 6, and the air outlet of the fuel cell stack is connected to the humid air inlet of the humidifier 5. The humid air outlet of the humidifier 5 is sequentially connected to the back pressure valve 8, the hydrogen-air mixing pipe 9, and the silencer 10. The hydrogen-air mixing pipe 9 is also connected to a hydrogen exhaust pipe.

[0036] In this embodiment, the air compressor 3 is controlled by the air compressor controller.

[0037] In this embodiment, an air pressure sensor 7 and a shut-off valve are also installed on the pipe between the dry air outlet of the humidifier 5 and the air inlet of the fuel cell stack 6. The oxygen supply system described in this embodiment is used in Embodiment 2.

[0038] Example 2

[0039] This embodiment is based on an oxygen supply control method for a fuel cell system according to the present invention. The method is used for a 130kW hydrogen fuel cell system operating in high-altitude areas and includes the following steps:

[0040] S1: Obtain current altitude 1500m and atmospheric pressure 84.9kPa.

[0041] S2: Given an altitude of 1500m and an atmospheric pressure of 84.9kPa, we can calculate the current oxygen content.

[0042] (1) Convert atmospheric pressure to Pascals: Atmospheric pressure = 84.9 kPa = 84900 Pa

[0043] (2) Calculate the partial pressure of oxygen (assuming the partial pressure of water vapor is zero): Partial pressure of oxygen = 84900 x 20.95% = 17786.55 Pa

[0044] (3) Calculate the oxygen content:

[0045] Oxygen content = partial pressure of oxygen / total atmospheric pressure

[0046] =17786.55Pa / 101325Pa

[0047] The calculation yielded the following:

[0048] Oxygen content ≈ 0.176

[0049] S3: The current oxygen content X1 is 0.176, which is less than the target oxygen content X2 (0.21). The inlet water temperature T1 is 68℃, which is less than the target water temperature T2 (69℃). Under the current operating conditions, the difference VΔ between the fuel cell system output voltage and the target voltage is 2.8V. Therefore, the air compressor speed will be increased by 15% to increase the oxygen flow rate. The back pressure valve opening will be reduced by 10% to lower the system back pressure and promote oxygen flow, thus adapting to the increased oxygen supply demand of the system.

[0050] S4: Under the current operating conditions, the difference VΔ between the fuel cell system output voltage and the target voltage is equal to 0.4V, and the single-cell voltage variance is equal to 20. This indicates that the oxygen supply is sufficient, and the system is operating normally and performing well. Stop adjusting the control parameters of the oxygen supply system, such as the air compressor speed and the back pressure valve opening.

Claims

1. A method for controlling oxygen supply in a fuel cell system, characterized in that, Includes the following steps: S1: Obtain current altitude and environmental pressure; S2: Calculate the current oxygen content based on ambient pressure; S3: Determine whether the current oxygen content X1 is lower than the target oxygen content X2; If the current oxygen content is lower than the target oxygen content, the infeed water temperature T1 is greater than or equal to the target temperature T2, and the difference between the fuel cell system output voltage and the target voltage VΔ under the current operating conditions is in the range of 2V to 3V, then the speed of the air compressor will be increased by 10% to 30% to increase the oxygen flow rate; the opening of the back pressure valve will be reduced to 5% to 15% to reduce the back pressure of the system and promote the flow of oxygen. If the current oxygen content reaches or exceeds the target oxygen content, the oxygen supply control parameters will not be adjusted, and the current altitude and air pressure will be continuously monitored. S4: Monitor airflow data to ensure that oxygen supply is continuously increasing; If, under the current operating conditions, the difference VΔ between the fuel cell system output voltage and the target voltage is within the range of 0.1V to 0.8V, and the single-cell voltage variance is less than 50%, it is determined that the oxygen supply is sufficient, the system is operating normally, and its performance is good. Therefore, the adjustment of the oxygen supply system control parameters, including the air compressor speed and the back pressure valve opening, is stopped. If the conditions that the difference VΔ between the fuel cell system output voltage and the target voltage is within the range of 0.1V to 0.8V, and the single-cell voltage variance is less than 50, are not met, then return to step S3 to increase the air compressor speed by 10% to 30% to increase the oxygen flow rate; reduce the back pressure valve opening to 5% to 15% to reduce the system back pressure and promote oxygen flow.

2. The oxygen supply control method for a fuel cell system according to claim 1, characterized in that, The target oxygen content X2 is 0.21 under standard atmospheric pressure.

3. The oxygen supply control method for a fuel cell system according to claim 1, characterized in that, The calculation process for the current oxygen content X1 is as follows: Oxygen content X1 = Partial pressure of oxygen / Total atmospheric pressure Among them, oxygen partial pressure refers to the partial pressure of oxygen in the current gas mixture.

4. The oxygen supply control method for a fuel cell system according to claim 3, characterized in that, oxygen partial pressure P O2 =PX, where P is atmospheric pressure and X is the mole fraction of oxygen in the atmosphere.

5. The oxygen supply control method for a fuel cell system according to claim 4, characterized in that, The atmospheric pressure mentioned is air pressure data, that is, the air pressure at sea level under standard atmospheric conditions, with a value of 101325 Pascals (Pa).

6. The oxygen supply control method for a fuel cell system according to claim 4, characterized in that, X is 20.95%.

7. The oxygen supply control method for a fuel cell system according to claim 3, characterized in that, Total atmospheric pressure refers to one standard atmosphere, which is 101.325 kPa.

8. The oxygen supply control method for a fuel cell system according to claim 1, characterized in that, The oxygen supply system includes an air filter (1), a flow meter (2), an air compressor (3), an intercooler (4), a humidifier (5), an electric stack (6), a back pressure valve (8), a hydrogen-air mixing pipe (9), and a silencer (10). The air filter (1), flow meter (2), air compressor (3), and intercooler (4) are connected in sequence and then connected to the dry air inlet of the humidifier (5); the dry air outlet of the humidifier (5) is connected to the air inlet of the fuel cell stack (6), and the air outlet of the fuel cell stack is connected to the humid air inlet of the humidifier (5); the humid air outlet of the humidifier (5) is connected in sequence to the back pressure valve (8), hydrogen-air mixing pipe (9), and silencer (10); the hydrogen-air mixing pipe (9) is also connected to the hydrogen tailpipe.

9. The oxygen supply control method for a fuel cell system according to claim 8, characterized in that, The air compressor (3) is controlled by an air compressor controller.

10. The oxygen supply control method for a fuel cell system according to claim 8, characterized in that, An air pressure sensor (7) and a shut-off valve are also installed on the pipe between the dry air outlet of the humidifier (5) and the air inlet of the fuel cell (6).

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