Try P.L.Zervas et al 'Mathematical Modelling of Fuel Cell Systems' NOVA Science Publishers ,2007 and 2008.
Also Energy Conversion and Management,47,p2883-2899,2006 and in Proceedings of Inst.of Mech.Engineers.Part A J.of Power and Energy,220(6),pp525-533,2006,
Also J.of Power Sources,185(2008),p345-355 and 181(2008)p.327-338.
Finally J.Hasikos, J.of Power Sources 193(2009)p258-268.