Macroscopic modeling of SOFC and PEFC fuel cells for the study of their coupling

The aim of the European project 'FELICITAS' is the development of fuel cell generators capable of meeting the heavy-duty transport demands for road, rail, and marine. The works presented are devoted to the evaluation of a new fuel cell hybridization sources which are coupled in series a high temperature solid oxide fuel cell (SOFC) fuelled by diesel and a low temperature polymer electrolyte fuel cell (PEFC). The SOFC therefore participates in the electrical power supply and also contributes to the purification process of fuel for the PEFC by the oxidation of a fraction of carbon monoxide. A macroscopic modelling approach has been developed. The complexity of a fuel cell lies in the consideration of its multiphysics phenomena: electrochemical, thermal and fluidic phenomena. This difficulty was overcome by using an equivalent electrical analogy to unify its three aspects, implemented and coupled these sub-models into a single Matlab/Simulink^TM subroutine. A SOFC stack model is proposed, applying the principle of electrical circuit analogy of the anode and the cathode, and a nodal method for the thermal behaviour is also developed. The fuel is a mixture of hydrogen, nitrogen, carbon monoxide, carbon dioxide and water vapour, which is the same composition obtained by a reformer. A test bench was specifically designed and built for testing of small stacks in order to validate the model. Two types of design stacks were studied: a free gas combustion technology in the anode and anode exhaust fluid technology collector. A model for isothermal PEFC stack has also been developed on the same principle. The experimental validation was made on a test bench in the laboratory. A library of components of a fluidic generator fuel cell was enriched (valve, flow meter, pressure regulator...) including a simplified model of air compressor. (author)