Calculation of Hydrogen Consumption for Fuel Cell Vehicles by Exhaust Gas Formulation

The hydrogen consumption of fuel cell vehicles (FCV) can be measured by the gravimetric, pressure and flow methods within a ±1% error. These are the methods acknowledged by ISO and SAE [1, 2], but require the test vehicles to be modified in order to supply hydrogen from an external, rather than the onboard tank. Consequently, technical assistance of the vehicle manufacturer is necessary for this modification, while various components in the test vehicle must be readjusted. For these reasons, a measurement method free of vehicle modification is in great demand. The present study therefore developed an “oxygen balance method” which determines the amount of hydrogen that has reacted with oxygen in the fuel cell stack by measuring the oxygen concentration in exhaust gas. The results of evaluation tests indicated a good possibility of the oxygen balance method to achieve measurement of FCV fuel consumption while at the same time promising the simplicity of testing equipment and procedure comparable with the carbon balance method that is applied to the measurement of fuel consumption for internal combustion engine vehicles (ICEV).