Design and investigation on a novel system coupling a natural gas reformer and a high temperature PEM fuel cell for automotive application

Environmental concerns stress the necessity of new solutions for energy supply both in the stationary and automotive field. In this context, fuel cells emerged as an interesting and promising solution, both for industrial and transport applications. Among these latter ones, high temperature PEM fuel cells systems are likely to be the most versatile solution, due to the relative high level of operative temperature, absence of water management problems, high tolerance to CO content and flexibility in fuel composition.

In comparison to conventional PEM fuel cells, which require almost pure hydrogen and water as inlet fuel, this new latter feature enables a wider range of possibilities in terms of fuel composition, which consistently increase the flexibility of the system. This work investigates the design and performance of an innovative system for hybrid vehicles.

This new set up, featuring the coupling of a flameless steam reformer and a high temperature PEM fuel cell will be implemented in the service vehicles of DTU university campus (Technical University of Denmark). The complete power plant layout is designed andits performance is studied by means of an in-house validated code.

The residual off-fuel coming from the fuel cell is burnt (in addition to the natural gas) in a catalytic burner to provide heat for the reformer and thereby reduce the need for required natural gas. The water content in the reformate inlet fuel isreduced to enhance the hydrogen molar fraction at a minimum level of 60 %.

Finally, the reduction of water content in the reformate gas implies the stream to be cooled; since the fuel cells requires the inletfuel temperature to be higher than 150 °C, a heat exchanger is designed to re-increase the temperature of the reformate gas at expenses of the combusted gas stream from the burner.