Injector flow measurement for fuel cell applications
View Patent ↗A method for determining the amount of fuel flow from a high pressure gas tank to the anode side of a fuel cell stack through pulsed injector. The anode sub-system pressure is measured just before the injector pulse and just after injector pulse and a difference between the pressures is determined. The difference between the pressures, the volume of the anode sub-system, the ideal gas constant, the anode sub-system temperature, the fuel consumed from the reaction in the fuel cell stack during the injection event and the fuel cross-over through membranes in the fuel cells of the fuel cell stack are used to determine the amount of hydrogen gas injected by the injector.
1. A method for determining a fuel flow through a pulsed device that provides hydrogen fuel from a hydrogen source to an anode side of a fuel cell stack, said method comprising:
determining when the device is opened and closed
determining a pressure of the anode side of the fuel cell stack just before opening the device;
determining a pressure of the anode side of the fuel cell stack just after closing the device; and
determining the fuel flow using the difference between the pressure just after closing the device and the pressure just before opening the device.
2. The method according to claim 1 wherein determining the pressure of the anode side includes using a pressure sensor.
3. The method according to claim 1 wherein the method determines a fuel flow through the pulsed device only when an anode bleed valve is closed.
4. The method according to claim 1 wherein the pulsed device is an injector.
5. The method according to claim 4 wherein determining the injector event includes determining a frequency and duty cycle of the injector.
6. The method according to claim 1 further comprising determining whether there is a leak in the anode sub-system during a decay duration by using the difference between the pressure just after closing the device and the pressure just before opening the device.
7. The method according to claim 6 wherein determining whether there is a leak includes using the equation:
N leak =( P 2 −P 3 ) V/RT−N io −N xoo
where N leak is the amount of leaking between device events, P 3 is the anode sub-system pressure after the decay duration, N io is the fuel consumed by the stack during the decay duration and N xoo is the fuel cross-over during the decay duration.
8. The method according to claim 1 wherein determining the fuel flow also includes using a volume of an anode sub-system and a temperature of the anode sub-system.
9. The method according to claim 8 wherein determining the fuel flow also includes using an ideal gas constant, the fuel consumed by the stack during the device event and fuel cross-over through membranes in fuel cells of the fuel cell stack during the device event.
10. The method according to claim 9 wherein determining the fuel flow includes using the equation:
N inj =( P 2 −P 1 ) V/RT+N ii +N xoi
where N inj is the amount of fuel flow, P 2 is the anode sub-system pressure after the device event, P 1 is the anode sub-system pressure before the device event, V is the anode sub-system volume, R is the ideal gas constant, T is the anode sub-system temperature, N ii is the fuel consumed by the stack during the device event, and N xoi is the fuel cross-over during the device event.
11. The method according to claim 9 wherein the fuel consumed by the stack during the device event is calculated from measured stack current.
12. The method according to claim 9 wherein the fuel cross-over during the device event is calculated based on membrane permeability.
13. A method for determining a fuel flow through a pulsed injector that injects hydrogen fuel from a hydrogen source to an anode side of a fuel cell stack, said method comprising:
determining injector events of when the injector is opened and closed using a frequency and duty cycle of the injector;
determining a pressure of the anode side of the fuel cell stack just before the injector is opened using a pressure sensor;
determining a pressure of the anode side of the fuel cell stack just after the injector is closed using the pressure sensor; and
determining the amount of fuel flow using the difference between the pressure just after the injector is closed and the pressure just before the injector is opened, a volume of an anode sub-system, a temperature of the anode sub-system and an ideal gas constant.
14. The method according to claim 13 wherein determining the fuel flow also includes using the fuel consumed by the stack during the injector events and fuel cross-over through membranes in fuel cells of the fuel cell stack during the injector events.
15. The method according to claim 14 wherein determining the fuel flow includes using the equation:
N inj =( P 2 −P 1 ) V/RT+N ii +N xoi
where N inj is the amount of fuel flow, P 2 is the anode sub-system pressure after the injector event, P 1 is the anode sub-system pressure before the injector event, V is the anode sub-system volume, R is the ideal gas constant, T is the anode sub-system temperature, N ii is the fuel consumed by the stack during the injector event, and N xoi is the fuel cross-over during the injector event.
16. The method according to claim 14 wherein the fuel consumed by the stack during the injectors event is calculated from measured stack current.
17. The method according to claim 14 wherein the fuel cross-over during the injector events is calculated based on membrane permeability.
18. The method according to claim 13 further comprising determining whether there is a leak in the anode sub-system during a decay duration between the injector events using the difference between the pressure just after closing the injector and the pressure just before opening the injector.
19. The method according to claim 18 wherein determining whether there is a leak includes using the equation:
N leak =( P 2 −P 3 ) V/RT−N io −N xoo
where N leak is the amount of leaking between injector events, P 3 is the anode sub-system pressure after the decay duration, N io is the fuel consumed by the stack during the decay duration and N xoo is the fuel cross-over during the decay duration.
20. A system for determining a fuel flow through an injector that provides hydrogen fuel from a hydrogen source to an anode side of a fuel cell stack, said system comprising:
means for determining injector events of when the injector is opened and closed;
means for determining a pressure of the anode side of the fuel cell stack just before opening the injector;
means for determining a pressure of the anode side of the fuel cell stack just after closing the injector; and
means for determining the fuel flow using the difference between the pressure just after closing the injector and the pressure just before opening the injector.
21. The system according to claim 20 wherein the means for determining the fuel flow uses the equation:
N inj =( P 2 −P 1 ) V/RT+N ii +N xoi
where N inj is the amount of fuel flow, P 2 is an anode sub-system pressure after the injector event, P 1 is the anode sub-system pressure before the injector event, V is the anode sub-system volume, R is the ideal gas constant, T is the anode sub-system temperature, N ii is the fuel consumed by the stack during the injector event, and N xoi is the fuel cross-over through fuel cell membranes during the injector event.
22. The system according to claim 20 further comprising means for determining whether there is a leak in an anode sub-system that uses the equation:
N leak =( P 2 −P 3 ) V/RT−N io −N xoo
where N leak is the amount of leaking between injector events, P 3 is the anode sub-system pressure after a decay duration between injector events, N io is the fuel consumed by the stack during the decay duration and N xoo is the fuel cross-over through fuel cell membranes during the decay duration.