Prediction of Flow Field in a MCFC Stack With Channels of Complex Shape

The flow passage in a molten-carbonate-fuel-cell (MCFC) stack consists of the cathode/anode channels of complex geometry and the inlet/outlet manifolds that supply and collect the gas to and from the channels. It is one of the major design concerns that the reacting fluid be uniformly distributed to each cell and to various regions of the electrode surface in the channel. The paper outlines the method to predict the flow characteristics in the flow passage of a multiple cell MCFC system. Rather than trying to obtain the finite volume solution over the entire channel directly, the channel with uniformly distributed trapezoidal shape supports is approximated by the equivalent porous medium. The effective permeability and the inertial resistance factor are estimated from a rigorous 3D finite volume calculation for a single periodic module of the channel. The pressure in the manifold is determined iteratively from the empirical head-loss relation in a tube. The volume change of the fluid due to chemical reaction is taken into consideration in the analysis. It is shown in the paper that the flow field in both cathode and anode channels is successfully computed and the mass flux to each cell can also be predicted. The pressure drop versus the flow rate for different stack-manifold arrangements is also discussed in the paper.