op in n U

by assuming that the local current density is a linear function of equations for porous electrodes based on volume averaging, which atical Simi-e pre-con-their ignifi-as as-e and steady 0).— equal by the i 00 Downlodistance ~first order approximation!. Both of these approximations are valid only under limited cell operating conditions. A comprehen-sive full cell model is necessary to explain the fuel cell performance. Previously, we developed a polarization model for the MCFC cathode based on volume averaging6 of variables in the three phases separately. A similar approach has been used by Prins-Jansen et al.7 to analyze the impedance of the MCFC cathode. This approach dif-fers from the conventional agglomerate model used to analyze the performance of the MCFC anode1 and cathode.1 As compared to the agglomerate model1 where macropores and micropores remain as separate entities. In this approach the pores in the electrode exist in a single continuum. Further, all three phases coexist within the po-rous electrode and reaction proceeds everywhere at the solid/melt has been adopted here. Detailed derivation of the mathem equations in the cathode was presented in our previous paper.6 lar equations can be derived for the anode. In this paper w sented the final governing equations along with the boundary ditions in each of the cathode, anode and the matrix and interfaces. Since the potential and the concentration varied s cantly along the thickness of the fuel cell, a 1-D model w sumed. Further, we did not consider corrosion of the cathod current collectors and assumed that the system was under state. Equations at the current collector cathode interface (x 5 CO2 and O2 enter at the cathode side. The concentrations were to the inlet concentrations and the current was carried entirel