A dynamic model for a single, spatially distributed molten carbonate fuel cell ͑MCFC͒ in cross-flow configuration is presented. The equations are formulated in dimensionless terms and are based on balances of mass, enthalpy, and charge. They include a detailed description of the electric potential field, reforming reactions inside the anode channel, mass transport resistance between the bulk gas phase and the electrochemical reaction zone inside the electrode pores, a catalytic combustion chamber, and the recycling of cathode exhaust gas. The simulation yields transient and spatially distributed profiles of temperatures, concentrations, gas fluxes, and current density as well as the cell voltage and the electric power over the full range of operating conditions. It is therefore a useful basis for system design, optimization, and control design of MCFC, applicable to any size of MCFC and transferable to other high-temperature fuel cells such as the solid oxide fuel cell. The complete set of model equations is presented in detail. Some exemplary steady state and transient simulation results are presented and compared to results from other models.Among the various types of fuel cells, the molten carbonate fuel cell ͑MCFC͒ is a promising device for stationary power and heat supply. Due to its high operating temperature of about 600°C, this concept has certain advantages over low-temperature fuel cell systems. The temperature is high enough to allow for internal reforming, which means to produce hydrogen from different types of fuel gases within the cell stack itself. Also due to the high temperature, no expensive catalysts are required; nickel and nickel oxide are sufficiently active as electrode catalysts. The coupling of electric energy production with heat or steam supply is feasible with this device. Also, the use of the hot exhaust gases for the generation of additional electric energy via a microturbine is possible. The temperatures are low enough to use cheap metallic materials for the cell, so no expensive ceramics are required, like in many solid oxide fuel cells ͑SOFCs͒, for example.The cell is tolerant with respect to carbon monoxide, so no extensive cleaning procedure is required for the feed gas, and a wide variety of different gaseous fuels can be applied, for example natural gas, bio gas, waste gas, and coal gas. Nevertheless, sulfur is a catalyst poison, so its concentration in the feed gas must be below a few ppm. Another drawback of the MCFC is its power density, which is considerably lower than that of a proton exchange membrane fuel cell ͑PEMFC͒, for example. This is mainly due to the typical current density of MCFC, which is about 150 mA/cm 2 . For comparison, PEMFCs are capable of delivering more than 1000 mA/cm 2 . Because of the high temperatures, the operation of the system is difficult. One must avoid strong temperature gradients and stay within a certain window of admissible temperatures. Chemical and electrochemical reactions slow down considerably in regions with low temperatures, whereas...
