System and method for determining the concentration of hydrogen in an anode recirculation circuit of a fuel cell system

摘要

A method of determining the concentration of hydrogen in an anode recirculation loop (18, 20) of a fuel cell stack (12), the method comprising: measuring the pressure of the anode off-gas discharged from the fuel cell stack (12); the pressure drop is measured across a recirculation pump (30); the temperature of the anode recirculation gas flowing through the recirculation circuit (18, 20) is measured; setting an arbitrary value for the percentage of hydrogen in the recirculation gas; the pressure drop across the anode side of the stack (12) is calculated; calculating the volume flow rate of the recirculation gas flowing through the anode side of the stack (12) as a function of the calculated pressure drop across the anode side of the stack (12), the percentage of hydrogen in the recirculation gas, the measured temperature and the measured pressure of the anode exhaust gas; the density of the recirculation gas flowing through the recirculation circuit (18, 20) is calculated using the calculated volume flow, the measured pressure drop and the speed of the recirculation pump (30); and the calculated density, measured temperature, and measured pressure drop are used to calculate a new percentage of hydrogen in the recirculation gas.