Patent ID: 8129056

Claim:
A method for determining the speed of a recirculation pump in an anode recirculation loop of a fuel cell stack based on a predetermined ratio of fresh hydrogen to recirculated hydrogen, said method comprising: measuring the pressure drop across the recirculation pump; measuring the temperature of the anode recirculation gas flowing through the recirculation loop; feeding fresh hydrogen into the recirculation loop; calculating the pressure drop across the anode side of the stack; calculating the volume flow of the recirculation gas through the anode side of the stack as a function of the calculated pressure drop across the anode side of the stack, the percentage of hydrogen in the recirculation gas, the measured temperature of the anode recirculation gas flowing through the recirculation loop and the measured pressure drop across the recirculation pump; and using the calculated volume flow and the amount of fresh hydrogen being fed into the recirculation loop to determine the speed of the pump to achieve the predetermined ratio.