Bond graph model of a solid oxide fuel cell with a C-field for mixture of two gas species

Abstract

A true bond graph model of a solid oxide fuel cell (SOFC) is presented in this paper. The constitutive relations of a C-field for two species of gases are formulated in order to model the cathode and the anode channels of the fuel cell. Moreover, an existing R-field model has been extended for modelling of forced convection of a mixture of two gas species. For given values of system operating pressure, the air source and hydrogen source pressures, the outlet pressures and the inlet gas compositions, the fuel utilization (FU), and air utilization (AU) are interpreted in terms of the partial pressures of the gases in the anode channel and cathode channel. The model is simulated and various static and dynamic characteristic curves for the SOFC are obtained. It is found that the model is capable of capturing all the essential dynamics of the SOFC. Availability of this bond graph model will aid in designing robust model-based control strategies for the fuel cell system and also for performing exergy analysis of the system.