Variable air utilization increases fuel cell membrane durability
View Patent ↗A fuel cell stack ( 10 ) is operated with a low air utilization which is very low when the stack is providing low current density, and is operated with air utilization increasing as a function of current density above a predetermined current density.
1. A method characterized by:
operating an evaporatively cooled fuel cell power plant in a manner to provide air utilization of less than about 40% while the power plant is producing electric power at current densities at or below a predetermined current density, and operating the fuel cell power plant with air utilization as a function of current density for current densities in excess of said predetermined current density, wherein said predetermined current density is about one-third of maximum current density.
2. The method of claim 1 , further comprising:
detecting a current of the fuel cell power plant; and
providing an amount of air to the fuel cell power plant based on the detected current.
3. The method of claim 1 , further comprising:
adjusting a temperature of the fuel cell power plant based on a difference between an air exit temperature and a coolant inlet temperature.
4. A method characterized by:
operating an evaporatively cooled proton exchange membrane fuel cell stack with a first predetermined air utilization when the stack is providing current density near maximum current density;
operating said fuel cell stack with a second predetermined air utilization which is less than half of said first predetermined air utilization when the stack is providing current density less than a predetermined current density; and
operating said fuel cell stack with air utilization between said second predetermined air utilization and said first predetermined air utilization as a function of current density provided by said stack between said predetermined current density and said maximum current density, wherein said predetermined current density is about one-third of maximum current density.
5. The method of claim 4 , further comprising:
detecting a current of the fuel cell stack; and
providing an amount of air to the fuel cell stack based on the detected current.
6. The method of claim 4 , further comprising:
adjusting a temperature of the fuel cell stack based on a difference between an air exit temperature and a coolant inlet temperature.