Development of a small vehicular PEM fuel cell system

This paper reports the development of components in a stack assembly and measurements of electrochemical characteristics of a proton exchange membrane (PEM) fuel cell stack. A novel test fixture together with a superposition approach is utilized to assess the Ohmic resistance across the stack. Then, a Tafel-kinetic equation for describing the voltage and current curve for all processes including electrode activation, Ohmic resistance and mass transfer was reported. It was found that the Ohmic resistance inside the fuel cell stack was markedly impacted by clamping torque of the stack. An optimum clamping torque of 90 kgf cm was determined based on measured Ohmic resistance. Uniformity and stability in the stack was verified by measuring cell voltage and temperature distribution. Finally, stack durability was tested by impelling a buggy over a relatively long duration.