Performance investigation of 2.4 kW PEM fuel cell stack in vehicles

The aim of this paper was to investigate the behaviour of a 2.4 kW PEM stack in dynamic conditions typical of vehicle applications, including urban driving cycles taken from European legislation. A management strategy of the main fuel cell system auxiliary components was chosen with the scope of minimizing the energy consumptions associated to humidification, cooling and reactant feeding operations. The results obtained provided the definition of a correlation diagram power-temperature, in particular the application of a statistical indicator of the cell voltage uniformity (coefficient of variation Cv) allowed the specification of a reliable working field in terms of stack durability in real applications. The tests effected on European driving cycles R40 and R47 evidenced that stack power increase rates up to 500 W/s were acceptable for the fuel cell system used in this paper, while for higher dynamics the stack working regularity was limited by low stoichiometric ratio values (R<1). However during fast transient phases (10 s as order of magnitude) excursions outside the optimal conditions of power, temperature and R resulted acceptable in terms of Cv (mostly lower than 4%).