An improved three-dimensional numerical analysis for a MCFC stack has been carried out to predict its performance. The continuity, Navier-Stokes, energy, and species equations are solved for the velocity, temperature, pressure and concentration distributions in the cathode and anode channels of a unit cell. The channel with the trapezoidal supports is approximated by an anisotropic porous medium, of which the effective permeability and conductivity are obtained by separate 3D FVM calculations.
The diffusion coefficient for each species is evaluated from a simplified formular for multicomponent mixtures. The flow rate to each cell in the stack is determined iteratively by coupling the manifold and channel flows to match the pressure drop for each cell to the corresponding flow rate.
The performance of a unit cell is estimated for a range of loads and utilization rates. This is an iterative process and is assumed to have converged when the cell voltage and the local current density fall within the specified convergence criterion. The results, which include the performance curve, the flow rates to each cell, etc., are satisfactory and are presented in the thesis along with the discussions on the effects of various components in the procedure.
