Fuel cell cold purging control method and fuel cell system

Abstract

The invention discloses a fuel cell cold purging control method and a fuel cell system, and the control method comprises the following steps: determining the maximum volume of a water distribution piece for triggering drainage by a liquid level sensor and the flow capacity of an exhaust valve under hydrogen side pressure during cold purging, and calculating the time I required for discharging the maximum volume of water; determining the preset dryness of stack purging based on a preset requirement, and obtaining the time II required for reaching the dryness; and determining the starting time and period of cold purging in combination with the time I and the time II. The fuel cell system comprises a pack shell, an electric pile and an air and hydrogen gas inlet and outlet pipeline, and the hydrogen gas outlet pipeline is provided with a water diversion piece which is communicated with a near-end water and hydrogen discharge pipeline. By quantitatively calibrating the cold purging strategy, setting the opening time and period of the drain valve, and combining the obliquely downward anti-liquid-accumulation layout of the tail exhaust pipeline and the multi-time drainage control of the far-end drain valve, the hydrogen side accumulated water is ensured to be completely discharged, icing is prevented from the two aspects of strategy and structure, and the operation reliability of the fuel cell engine is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell cold purge control method and a fuel cell system. Background Art

[0002] During low-temperature shutdown of a fuel cell engine, water inside the stack needs to be blown out to prevent freezing at low temperatures, which could freeze and damage the stack. Water on the air side, purged with high air flow, flows directly through the flow channel into the tailpipe and is discharged into the atmosphere. Water on the hydrogen side, under the influence of hydrogen pressure, enters the water distributor and is then discharged through the drain valve. An inappropriate cold purge strategy can prevent the hydrogen side water from being completely discharged, leading to freezing of the drain valve and tailpipe at low temperatures. This can cause the next startup to fail, resulting in engine inoperability and impacting engine reliability. Therefore, developing an appropriate cold purge strategy is crucial.

[0003] Related technologies such as Chinese patents CN114335617B, CN114865024A, CN112993330A, etc., although they involve control methods and devices for shutdown purging of fuel cell systems, have different designs in terms of adaptive control, self-heating combined with cold purging, high and low temperature two-stage purging, avoiding the vicious cycle of membrane drying, and remote setting of purging time periods. However, they are all irrelevant to preventing the tail pipe and drain valve from freezing, and fail to solve the problem of freezing of related components due to inappropriate cold purging strategies, which in turn affects engine startup and operation. Summary of the Invention

[0004] The purpose of the present invention is to provide a fuel cell cold purge control method and a fuel cell system to solve the problems in the prior art.

[0005] To this end, the present invention provides a fuel cell cold purge control method, the steps comprising:

[0006] S100, determining the maximum volume of the water distribution component when the liquid level sensor triggers drainage, and simultaneously determining the flow capacity of the exhaust valve under the hydrogen side pressure during the cold purge process, and calculating the time required to drain the maximum volume of water;

[0007] S200, determining a preset dryness level 1 for stack purge based on a preset requirement, and determining a second time required to reach the preset dryness level 1;

[0008] S300 , determining a start time and cycle of cold purge based on time 1 and time 2.

[0009] As a further description of the above technical solution, in step S100, the step of calculating time 1 includes:

[0010] Time 1 = maximum volume / flow capacity.

[0011] As a further description of the above technical solution, in step S200, the preset dryness 1 includes a preset impedance value and a preset relative humidity, and the preset impedance value is 0.3-0.6Ω·cm 2 , the preset relative humidity is 30%-50% RH.

[0012] As a further description of the above technical solution, it also includes purging the remote drain pipe, and the steps include: after the cold purge is completed, opening the water distribution component with a preset opening time and cycle to purge the remote drain pipe multiple times.

[0013] As a further description of the above technical solution, the cycle of purging the remote drain pipe is:

[0014] Single opening time: single closing time = 2:8;

[0015] The water distribution component purges the remote drainage pipe 9-11 times.

[0016] Also provided is a fuel cell system using the fuel cell cold purge control method, comprising: a pack housing;

[0017] A battery stack, the battery stack being disposed in the pack housing;

[0018] an air intake pipeline, connected to the fuel cell stack, and the fuel cell stack discharges air through an air exhaust pipeline;

[0019] A hydrogen inlet pipeline is connected to the fuel cell stack, a hydrogen exhaust pipeline is connected to the fuel cell stack, and a water distributor is provided on the hydrogen exhaust pipeline, which is connected to a proximal drainage pipeline and a proximal hydrogen exhaust pipeline.

[0020] As a further description of the above technical solution, it also includes a remote drainage pipeline, which is connected to the pack shell.

[0021] As a further description of the above technical solution, the air intake pipeline is sequentially provided with an air filter, an air compressor, an intercooler, an intake valve and an inlet air pressure sensor; the air exhaust pipeline is provided with an outlet air pressure sensor and a tail exhaust valve; and the air intake pipeline and the air exhaust pipeline are provided with a humidifier.

[0022] As a further description of the above technical solution, a proximal drain valve is provided on the proximal drain pipeline, and a proximal exhaust valve is provided on the proximal hydrogen exhaust pipeline.

[0023] As a further description of the above technical solution, a distal drain valve is provided on the distal drain pipeline, and the distal drain pipeline is connected to the proximal drain pipeline.

[0024] Beneficial effects:

[0025] The present invention provides a fuel cell cold purge control method and a fuel cell system. By quantitatively calibrating the cold purge strategy, that is, determining the maximum drainage volume of the water distribution component, the flow capacity of the exhaust valve and the purge time parameters, the drain valve opening time and cycle are set. Combined with the downward slanted anti-liquid accumulation layout of the tail drain pipeline and the multiple drainage control of the remote drain valve, it is ensured that the water accumulated on the hydrogen side is completely discharged during the cold purge. From the two aspects of strategy design and structural optimization, the freezing of the drain valve and the tail drain pipeline at low temperatures is systematically prevented, thereby improving the operating reliability of the fuel cell engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a flow chart of the fuel cell cold purge control method provided by the present invention.

[0028] Figure 2 Schematic diagram of the fuel cell system provided by the present invention.

[0029] In the figure: 1. Air filter; 2. Air compressor; 3. Intercooler; 4. Inlet valve; 5. Humidifier; 6. Tail exhaust valve; 7. Inlet air pressure sensor; 8. Outlet air pressure sensor; 9. Fuel cell; 10. Water distribution component; 11. Remote drain valve; 12. Near drain valve; 13. Exhaust valve. DETAILED DESCRIPTION

[0030] The present invention may be more readily understood by referring to the following detailed description of preferred embodiments of the present invention and the included Examples. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention pertains. In the event of a conflict, the definitions in this specification shall prevail.

[0031] The present invention provides a fuel cell cold purge control method and a fuel cell system, which solves the problem in the prior art that water stored in the fuel cell stack freezes at low temperatures, damages the membrane electrode, causes the next startup failure, and affects the reliable operation of the engine. Water on the hydrogen side is blown into the water distribution component. If the water in the water distribution component cannot be completely discharged, the proximal drain valve connected to it will cause freezing. If the exhaust valve fails, the drain valve will not have time to heat and melt the ice, and the nitrogen replacement process cannot be completed, resulting in startup failure and affecting the reliable operation of the engine.

[0032] The technical concept of the present invention is to quantitatively calibrate the cold purge strategy, that is, to determine the maximum drainage volume of the water distribution component, the flow capacity of the exhaust valve and the purge time parameters, set the drain valve opening time and cycle, and combine the downward slanted anti-liquid accumulation layout of the tail drain pipeline and the multiple drainage control of the remote drain valve to ensure that the water accumulated on the hydrogen side is completely discharged during cold purge. From the two aspects of strategic design and structural optimization, the freezing of the drain valve and the tail drain pipeline at low temperatures is systematically prevented, thereby improving the operating reliability of the fuel cell engine.

[0033] like Figure 1 As shown, a fuel cell cold purge control method includes:

[0034] S100 determines the maximum volume V1 of the water distribution element 10 when the liquid level sensor triggers drainage. Simultaneously, the flow capacity qSLPM of the exhaust valve 13 under the hydrogen-side pressure during the cold purge process is determined, and the time required to drain the maximum volume of water, t1, is calculated. V1 can be determined by installing a liquid level sensor (e.g., a capacitive or float-type sensor) on the water distribution element 10. Liquid water can be slowly injected into the water distribution element 10, the water level at the time the sensor is triggered recorded, and the corresponding volume calculated based on the internal geometric dimensions (cross-sectional area, height, etc.) of the water distribution element 10. The flow capacity qSLPM can be determined by directly measuring the hydrogen flow rate when the exhaust valve 13 is fully open using an external flowmeter (e.g., a mass flowmeter) under cold purge conditions, i.e., when the hydrogen-side operating pressure is stable at a set value, such as the hydrogen pressure during fuel cell system shutdown. During testing, the pressure must be kept constant, and the volume of gas discharged per unit time is recorded and converted to the flow rate qSLPM under standard conditions (e.g., 0°C, 1 atm). The calculation steps for the time t1 required to completely drain the water in V1 are:

[0035] Time 1 = maximum volume / flow capacity, i.e. t1 = V1 / q;

[0036] S200, based on the preset requirements, determines the preset dryness 1 of the stack 9, and determines the time 2 required to reach the preset dryness 1. Step S200 is specifically for the calibration of time 2. During the calibration process, the stack 9 is purged to the appropriate dryness according to the required impedance value of the stack 9, and the shortest time t2 for purging the stack 9 to the appropriate dryness is determined. It should be noted that the appropriate dryness is the preset impedance value after purging of 0.3-0.6Ω·cm 2 , the preset relative humidity after purging is 30%-50%RH.

[0037] S300, based on time one and time two, determines the start time and cycle of cold purge. After determining the start time and cycle of cold purge, that is, the start time of drainage is t1, and the start time of blowing the battery stack 9 to the appropriate dryness is t2. While ensuring that all the water in the water distribution component 10 can be discharged, it can also ensure that the hydrogen discharge concentration meets the national standard requirements, thereby ensuring that the water in the water distribution component 10 can be completely discharged and the near-section drainage valve will not freeze.

[0038] In one embodiment, the tail drain pipe is arranged to be inclined downward to ensure that no liquid accumulates inside the tail drain pipe and to prevent the tail drain pipe from freezing.

[0039] In one embodiment, the remote drain pipe is further purged, and the steps include: after the cold purge is completed, the remote drain valve 11 is opened with a preset opening time and cycle to purge the remote drain pipe multiple times. The cycle of the remote drain pipe purge is:

[0040] Single opening time: single closing time = 2:8;

[0041] The water distribution member 10 purges the remote drain pipe 9-11 times, which can effectively solve the problem of water easily accumulating inside the curved pipe at the connection between the remote drain valve 11 and the battery stack 9, causing the remote drain pipe and the drain valve to freeze.

[0042] like Figure 2 As shown, in one embodiment, a fuel cell system applying the above fuel cell cold purge control method includes: a pack housing;

[0043] A battery stack 9, the battery stack 9 being disposed in the pack housing;

[0044] The air intake pipeline is connected to the fuel cell stack 9, and the fuel cell stack 9 discharges air through the air exhaust pipeline; wherein, the air intake pipeline is sequentially provided with an air filter 1, an air compressor 2, an intercooler 3, an intake valve 4 and an inlet air pressure sensor 7, and the air exhaust pipeline is provided with an outlet air pressure sensor 8 and a tail exhaust valve 6, and there is a humidifier 5 in the air intake pipeline and the air exhaust pipeline.

[0045] The hydrogen inlet and exhaust lines are connected to the fuel cell stack 9. A water distributor 10 is provided on the hydrogen exhaust line, which is connected to the proximal drain line and the proximal hydrogen exhaust line. A proximal drain valve 12 is provided on the proximal drain line, and a proximal exhaust valve 13 is provided on the proximal hydrogen exhaust line.

[0046] Optionally, a remote drainage pipeline is further included, which is connected to the pack shell and the internal battery stack 9. A remote drainage valve 11 is provided on the remote drainage pipeline, and the remote drainage pipeline is connected to the proximal drainage pipeline.

[0047] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fuel cell cold purge control method, characterized in that the steps include: S100, determining the maximum volume of the water distribution component when the liquid level sensor triggers drainage, and simultaneously determining the flow capacity of the exhaust valve under the hydrogen side pressure during the cold purge process, and calculating the time required to drain the maximum volume of water; S200, determining a preset dryness level 1 for stack purge based on a preset requirement, and determining a second time required to reach the preset dryness level 1; S300 , determining a start time and cycle of cold purge based on time 1 and time 2.

2. The fuel cell cold purge control method according to claim 1, characterized in that: In step S100, the calculation step of time 1 includes: Time 1 = maximum volume / flow capacity.

3. The fuel cell cold purge control method according to claim 1, characterized in that: In step S200, the preset dryness 1 includes a preset impedance value and a preset relative humidity, wherein the preset impedance value is 0.3-0.6Ω·cm 2 , the preset relative humidity is 30%-50% RH.

4. The fuel cell cold purge control method according to claim 1, characterized in that: It also includes purging the remote drain pipe, and the steps include: after the cold purge is completed, opening the remote drain valve with a preset opening time and cycle to purge the remote drain pipe multiple times.

5. The fuel cell cold purge control method according to claim 4, characterized in that: The cycle for purging the remote drain pipe is: Single opening time: single closing time = 2:8; The water distribution component purges the remote drainage pipe 9-11 times.

6. A fuel cell system using the fuel cell cold purge control method according to any one of claims 1 to 5, characterized in that: include: pack shell; A battery stack, the battery stack being disposed in the pack housing; an air intake pipeline, connected to the fuel cell stack, and the fuel cell stack discharges air through an air exhaust pipeline; A hydrogen inlet pipeline is connected to the fuel cell stack, a hydrogen exhaust pipeline is connected to the fuel cell stack, and a water distributor is provided on the hydrogen exhaust pipeline, which is connected to a proximal drainage pipeline and a proximal hydrogen exhaust pipeline.

7. The fuel cell system according to claim 6, characterized in that A distal drainage pipeline is also included, and the distal drainage pipeline is connected to the pack shell.

8. The fuel cell system according to claim 6, wherein: The air intake pipeline is sequentially provided with an air filter, an air compressor, an intercooler, an intake valve and an inlet air pressure sensor; the air exhaust pipeline is provided with an outlet air pressure sensor and a tail exhaust valve; and the air intake pipeline and the air exhaust pipeline are provided with a humidifier.

9. The fuel cell system according to claim 6, wherein: The proximal drain pipe is provided with a proximal drain valve, and the proximal hydrogen exhaust pipe is provided with a proximal exhaust valve.

10. The fuel cell system according to claim 7, wherein: A distal drain valve is provided on the distal drain pipeline, and the distal drain pipeline is connected to the proximal drain pipeline.

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