Modeling Intermediate Temperature Protonic Ceramic Fuel Cells

Thursday, 30 July 2015: 11:40
Alsh (Scottish Exhibition and Conference Centre)
K. J. Albrecht, C. Duan, R. O'Hayre, and R. J. Braun (Colorado School of Mines)
Protonic ceramics fuel cells (PCFC) have emerged as a promising candidate for distributed power generation and synthetic fuel production. The cells offer the potential for reduced temperature operation (~500°C) which enables faster startup times, longer life, and lower material cost components to be used compared to their oxygen ion conducting counterparts. The development of a protonic ceramic fuel cell computational modeling tool is imperative to the design and implementation of systems. A framework is presented for a predictive cell-level, interface charge transfer PCFC model capturing the mixed conducting nature of the protonic ceramic materials. The model employs a 1-D channel-level modeling strategy (Fig. 1) where fuel depletion and flow configuration effects are resolved and coupled to a semi-empirical electrochemical model. Modeling results calibrated against experimental data of a state-of-the-art PCFC composition are presented.

            The lower cell temperature and hydrogen removal from the anode channel present unique operational features which are considered in the present work. In particular, a thermodynamic analysis is presented for operating regimes where solid carbon formation is not thermodynamically favorable. Simulation results are presented for the operation of the cell over a variety of operational regimes. Model predicted distributions of gas phase species, temperature, and local current density are resolved. The model predicted cell performance when operating on a humidified methane fuel source with steam-to-carbon ratio (S/C) of 2.4 at 500oC and 80% utilization indicates a power density greater than 0.100 W/cm2 is attainable at an average current density of 0.15 A/cm2. Model-predicted cell performance is explored under various operating conditions (Temperature, utilization, S/C) and an evaluation of reactant flow configuration (co- vs. counter-flow) is also presented.