A fuel cell air system and method of controlling the same

Abstract

The application provides a fuel cell air system and a control method thereof, the system comprising an air compressor, a intercooler, a humidifier, a fuel cell stack, a water distribution structure, an expander, a motor and a clutch arranged between the air compressor and the expander, and a three-way valve arranged on an air inlet pipeline. During operation, the three-way valve and the electromagnetic clutch are controlled according to the monitored expander temperature, so that the fuel cell air system can effectively avoid the start failure caused by the expander jam under low-temperature conditions, especially under low-temperature cold start conditions, and effectively widen the reliability and application range of the fuel cell system.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically to a fuel cell air system and its control method. Background Technology

[0002] The exhaust gas temperature from a fuel cell stack typically ranges from 60 to 90 degrees Celsius, with an absolute pressure between 120 kPa and 280 kPa. Currently, a more advanced technology utilizes an expander for energy recovery. To save space and reduce component complexity, a common fuel cell air system coaxially connects the air compressor, control motor, and expander. The control motor drives the air compressor's pressure roller to rotate, and the exhaust gas from the fuel cell stack drives the expander's rotation, reducing motor torque and thus achieving partial energy recovery.

[0003] However, the actual operating conditions of fuel cell systems in vehicles are highly variable, including transient processes such as startup, operation, load changes, purging, and standby; the operating environment is also highly variable, potentially experiencing temperatures as low as -40 degrees Celsius and as high as 60 degrees Celsius or higher. The exhaust gas from fuel cells contains a large amount of water vapor, which, under low-temperature conditions, especially cold-start conditions, precipitates and forms liquid water that freezes. According to the current air system architecture, this freezing of liquid water may cause the expander to seize, resulting in the air compressor malfunctioning and ultimately causing the fuel cell system to fail to start. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a fuel cell air system and its control method. This system effectively avoids start-up failure caused by expander jamming under low-temperature conditions, especially low-temperature cold start conditions, thus significantly expanding the reliability and applicability of the fuel cell system. Specific details are as follows:

[0005] A fuel cell air system, the basic components of which include an air compressor, an intercooler, a humidifier, a fuel cell stack, a water distribution structure, and an expander.

[0006] Based on the air delivery path in the fuel cell air system, it can be divided into two parts: the air inlet pipeline and the air exhaust pipeline. The air inlet pipeline includes at least an air compressor, an intercooler, and a humidifier. After being compressed by the air compressor, the air enters the intercooler for cooling, then enters the humidifier to increase its humidity before entering the fuel cell stack to participate in the electrochemical reaction. The air exhaust pipeline includes at least a water separator and an expander. The humid air discharged from the fuel cell stack first enters the humidifier to humidify the incoming air, then enters the water separator for gas-liquid separation, and finally enters the expander to perform work and recover energy before being discharged.

[0007] A three-way valve is installed on the air outlet pipeline of the air compressor. The first outlet of the three-way valve is connected to the intercooler, and the second outlet is connected to the air inlet pipeline of the expander, thereby forming a high-temperature air bypass that directly connects the air compressor to the expander, allowing at least a portion of the high-temperature air output by the air compressor to be directly delivered to the expander.

[0008] The expander and the air compressor are coaxially arranged, and a drive motor and an electromagnetic clutch are provided between them. A first temperature sensor is provided in the air intake pipe of the expander or inside the expander. The electromagnetic clutch performs an opening or closing action based on the monitoring result of the first temperature sensor.

[0009] Furthermore, the air compressor is equipped with an air filter and a flow meter on its air intake pipe.

[0010] Furthermore, an exhaust throttle valve is provided on the air exhaust pipe of the fuel cell stack.

[0011] Furthermore, the second outlet of the three-way valve opens or closes based on the monitoring results of the first temperature sensor. Preferably, the opening degree of the second outlet of the three-way valve is adjusted according to the monitoring results of the first temperature sensor, so as to more accurately control the distribution of high-temperature air between the first and second outlets. More preferably, a second temperature sensor is provided on the outlet pipeline of the air compressor, and the opening degree of the second outlet of the three-way valve is adjusted according to the monitoring results of the first and second temperature sensors, so as to more accurately control the temperature of the expander.

[0012] Based on the aforementioned fuel cell air system, this invention further provides a control method for a fuel cell air system, comprising:

[0013] The system reads the monitoring result from the first temperature sensor and compares it with a preset threshold. When the monitoring result is lower than the preset threshold, the electromagnetic clutch disengages to prevent the expander from icing and jamming, which could affect the normal operation of the air compressor. When the monitoring result is higher than the preset threshold, the electromagnetic clutch engages to continue utilizing the expander to recover energy and assist the air compressor in operation. Specifically, the preset thresholds for disengaging and engaging the electromagnetic clutch can be the same or different; this invention does not impose any special restrictions on this.

[0014] Furthermore, when the monitoring result of the first temperature sensor is lower than a preset threshold, the second outlet of the three-way valve is opened, thereby directly delivering the high-temperature air generated by the air compressor to the intake pipe of the expander. This high-temperature air heats the expander, preventing potential icing or eliminating any icing or jamming issues. Specifically, the preset temperature threshold for opening the second outlet of the three-way valve can be set according to actual needs, and can be the same as or different from the temperature threshold for the electromagnetic clutch to perform the open / close action. This invention does not impose any special limitations on this.

[0015] Furthermore, the opening degree of the second outlet of the three-way valve can be adjusted according to the monitoring results of the first temperature sensor in order to control the temperature of the expander within the design range.

[0016] Furthermore, the opening degree of the second outlet of the three-way valve can be adjusted according to the monitoring results of the first and second temperature sensors, so as to more accurately control the temperature of the expander within the design range.

[0017] The fuel cell air system and its control method provided by this invention can disconnect the coaxial state of the air compressor and expander by using a clutch when the temperature is too low, so as to avoid the expander from affecting the normal operation of the air compressor due to low temperature icing. Furthermore, it can directly supply high temperature air to the expander when necessary to prevent or eliminate icing. Thus, the fuel cell air system can effectively avoid start-up failure caused by expander jamming under low temperature conditions, especially under low temperature cold start conditions, effectively expanding the reliability and applicability of the fuel cell system. Attached Figure Description

[0018] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0019] Figure 1 A schematic diagram of the fuel cell air system in the embodiment is provided;

[0020] Figure 2 A flowchart of the control method for the fuel cell air system in the embodiment is provided.

[0021] Explanation of reference numerals in the attached drawings: 1-Air filter; 2-Flow meter; 3-Air compressor; 4-Three-way valve; 5-Intercooler; 6-Humidifier; 7-Fuel cell stack; 8-Water distribution structure; 9-Expander; 10-Drive motor; 11-Electromagnetic clutch; 12-High-temperature air bypass; 13-First temperature sensor; 14-Second temperature sensor. Detailed Implementation

[0022] Embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0023] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one 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.

[0024] like Figure 1 As shown, a specific embodiment of the present invention provides a fuel cell air system, including an air filter 1, a flow meter 2, an air compressor 3, a three-way valve 4, an intercooler 5, a humidifier 6, a fuel cell stack 7, a water distribution structure 8, and an expander 9. A drive motor 10 and an electromagnetic clutch 11 are arranged between the air compressor 3 and the expander 9.

[0025] Air filter 1, flow meter 2, air compressor 3, three-way valve 4, intercooler 5, and humidifier 6 are installed on the air inlet pipeline of fuel cell stack 7. Air compressor 3 is driven by drive motor 10, and expander 9 uses its recovered energy to assist air compressor 3. A second temperature sensor 14 is installed on the outlet pipeline of air compressor 3. The first outlet of three-way valve 4 is connected to intercooler 5, and the second outlet is directly connected to the inlet pipeline of expander 9. Intercooler 5 uses a cooling medium to cool the high-temperature air generated by air compressor 3; the circulation system of the cooling medium is not detailed here. Humidifier 6 uses the humid air discharged from fuel cell stack 7 to humidify the inlet air to meet the operating requirements of fuel cell stack 7.

[0026] The water separation structure 8 and the expander 9 are installed on the air exhaust pipe of the fuel cell stack 7. The humid air discharged from the fuel cell stack 7 first enters the humidifier 6 to humidify the air entering the stack, and then enters the water separation structure 8 (such as a conventional gas-liquid separator) for gas-liquid separation; the separated gas phase enters the expander 9 to perform work and recover energy, and finally is discharged from the fuel cell air system.

[0027] Specifically, the expander 9 is equipped with a first temperature sensor 13. When the temperature is detected to be lower than the preset first threshold, the control device (not shown) causes the electromagnetic clutch 11 to disengage, so as to prevent the abnormal state of the expander 9 from affecting the normal operation of the air compressor 3. When the temperature is detected to be higher than the preset first threshold, the electromagnetic clutch 11 is then caused to close.

[0028] The second outlet of the three-way valve 4 is directly connected to the intake pipe of the expander 9, thus forming a high-temperature air bypass 12 that connects directly from the air compressor 3 to the expander 9. Under normal operating conditions, the first outlet of the three-way valve 4 is open and the second outlet is closed. However, when the first temperature sensor 13 detects that the temperature is lower than a preset second threshold, the second outlet is opened, and the high-temperature air output from the air compressor 3 is used to heat the expander 9. The specific opening degree of the second outlet is controlled according to the monitoring results of the first temperature sensor 13 and the second temperature sensor 14.

[0029] Regarding the specific threshold for temperature monitoring, those skilled in the art can flexibly set it according to the actual situation. The first and second thresholds mentioned above can be the same or different.

[0030] Furthermore, this embodiment provides a preferred control method for the above-described fuel cell air system, such as... Figure 2 As shown, the control method includes the following steps:

[0031] S1: Read the monitoring results of the first temperature sensor 13 and the second temperature sensor 14;

[0032] S2: Compare the monitoring result of the first temperature sensor 13 with the preset first threshold and second threshold. If it is lower than the first threshold, proceed to step S31; if it is higher than the first threshold but lower than the second threshold, proceed to step S41; if it is higher than the second threshold, proceed to step S5.

[0033] S31: The electromagnetic clutch 11 performs a disengagement action and opens the second outlet of the three-way valve 4. The specific opening degree is controlled according to the monitoring results of the first temperature sensor 13 and the second temperature sensor 14.

[0034] S32: When the monitoring result of the first temperature sensor 13 is higher than the first threshold, the electromagnetic clutch 11 is closed, so that the expander 9 can use its recovered energy to assist the air compressor 3 in working.

[0035] S33: When the monitoring result of the first temperature sensor 13 is higher than the second threshold, the second outlet of the three-way valve 4 is closed, and step S5 is executed;

[0036] S41: The electromagnetic clutch 11 performs a closing action and opens the second outlet of the three-way valve 4. The specific opening degree is controlled according to the monitoring results of the first temperature sensor 13 and the second temperature sensor 14.

[0037] S42: When the monitoring result of the first temperature sensor 13 is higher than the second threshold, the second outlet of the three-way valve 4 is closed, and step S5 is executed;

[0038] S5: Put the fuel cell air system into normal operation, that is: the electromagnetic clutch 11 is in the closed state and the second outlet of the three-way valve 4 is in the closed state.

[0039] Various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are 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 chosen to best explain the principles, practical application, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell air system characterized by, The air compressor, the intercooler, the humidifier, the fuel cell stack, the water distribution structure and the expander are provided, the air compressor, the intercooler and the humidifier are arranged on the air inlet pipeline of the fuel cell stack, the water distribution structure and the expander are arranged on the air exhaust pipeline of the fuel cell stack, and the humidifier is configured to humidify the inlet air by using the wet air from the fuel cell stack. A three-way valve is arranged on the outlet pipeline of the air compressor, a first outlet of the three-way valve is connected to the intercooler, and a second outlet is connected to the inlet pipeline of the expander. The expander and the air compressor are coaxially arranged, and a driving motor and an electromagnetic clutch are arranged between the expander and the air compressor, a first temperature sensor is arranged on the inlet pipeline of the expander or in the expander, and the electromagnetic clutch performs the opening or closing action according to the monitoring result of the first temperature sensor.

2. A fuel cell air system according to claim 1, wherein, An air filter and a flow meter are arranged on the inlet pipeline of the air compressor.

3. A fuel cell air system according to claim 1, wherein, An exhaust throttle valve is arranged on the air exhaust pipeline of the fuel cell stack.

4. The fuel cell air system of claim 1, wherein, The second outlet of the three-way valve performs the opening or closing action according to the monitoring result of the first temperature sensor.

5. A fuel cell air system according to claim 4, wherein, The opening degree of the second outlet of the three-way valve is adjusted according to the monitoring result of the first temperature sensor.

6. A fuel cell air system according to claim 4, wherein, A second temperature sensor is arranged on the outlet pipeline of the air compressor, and the opening degree of the second outlet of the three-way valve is adjusted according to the monitoring results of the first temperature sensor and the second temperature sensor.

7. A control method of a fuel cell air system, characterized by, The fuel cell air system is the fuel cell air system of any one of claims 1-6, and the control method comprises: The monitoring result of the first temperature sensor is read and compared with a preset threshold value, when the monitoring result is lower than the preset threshold value, the electromagnetic clutch performs the opening action, and when the monitoring result is higher than the preset threshold value, the electromagnetic clutch performs the closing action.

8. The method of claim 7, wherein the air system is a fuel cell air system. When the monitoring result of the first temperature sensor is lower than the preset threshold value, the second outlet of the three-way valve is opened, so that the high-temperature air generated by the air compressor is transported into the inlet pipeline of the expander.

9. The method of claim 7, wherein the air system is a fuel cell air system. The opening degree of the second outlet of the three-way valve is adjusted according to the monitoring result of the first temperature sensor.

10. The method of claim 7, wherein the air system is a fuel cell air system. The opening degree of the second outlet of the three-way valve is adjusted according to the monitoring results of the first temperature sensor and the second temperature sensor.

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