Fuel Cell System for Two-Wheeled Vehicles

Direct methanol fuel cell (DMFC) system is a compact lightweight system as it eliminates the need of a complex reformer unit. Moreover, since the methanol-water-solution used as fuel does not correspond to a flammable substance, it is thought that convenience is high.

We have developed the hybrid scooter integrated with the DMFC system and the Li-ion rechargeable batteries, and optimized various parameters related to the performance and the efficiency. The power output of the DMFC system was adjusted to the value necessary for a constant ground run in 30 km/h of a commercial small electric scooter. All the system components had to be constituted in the limited space and under the restricted weight conditions.

The net-power-output of the system was examined under various air flow rate, fuel flow rate and methanol concentration conditions. We confirmed that the maximum net-output of the system was obtained at a condition different from one at the maximum gross-output conditions, because the increase of the gross-output had been accompanied by the increase of the auxiliary power consumptions. It was clearly found that the trade-off relation of the gross-output increase and the auxiliary power consumption increases must be considered to set up the optimized operating condition of the system.