Validation of Test Procedure for Measuring the Fuel Consumption of Production-Model FCVs 2019-01-0382
Factors affecting the measurement of the fuel consumption of FCVs were analyzed to reveal their sensitivity. The method for measuring fuel consumption described in the Worldwide harmonized Light vehicles Test Procedures (WLTP) is to measure the hydrogen consumption by using an electric precision balance and off-vehicle tanks (not on-vehicle tanks). This is unique compared with conventional vehicles such as petrol-engine vehicles and pure-electric vehicles. Therefore, we examined the sensitivities of the effect of hydrogen consumption determination, the effect of hydrogen supply pipe design, and the effect of hydrogen supply pipe management. The experiments were conducted with two production models of FCVs having different FC management systems. The effects were quantitatively evaluated by comparing the fuel consumption rate driving in the Worldwide Light-duty Test Cycles (WLTC). First, the hydrogen consumption amounts of the FCVs were measured with the gravimetric method. Then, a quantitative sensitivity analysis of the factors was conducted based on a hypothetical vehicle with a fuel consumption rate of 0.67 kg/100 km in the Low phase. All factors described in this paper were less than 0.5%, meaning that the effects of factors unique to FCVs are minor compared with those for conventional vehicles. As a result, the method for testing the fuel consumption rate of FCVs described in WLTP is shown to be practical. To the best of our knowledge, this is the first validation of the test procedure for measuring the fuel consumption of production-model FCVs by a national laboratory.