Parametric study of the tubular SOFC power cycle with a thermodynamic model

This work focuses on modeling and performance evaluation of an anodic re-circulation system including ejector technology, pre-reformer and solid oxide fuel cells (SOFC). An improved one-dimensional dynamic model of a simple tubular SOFC cycle components in the engineering equation solver (EES) environment is presented. In this simulation, ejector and pre-reformer components are modeled thermodynamically and a simple electrochemical SOFC model is developed all these models are coupled together to predict the operation of the cycle. The goal is to predict the effect of input parameters such as fuel mixing ratio and temperature on output parameters (i.e. pressure ratio increase, outlet temperature and molar fractions). Therefore the model determines the pressure, temperature and fuel composition variations of each component and the complete cycle at different points. For instance the model for ejector predicts the effect of mixing ratio and temperature on the pressure ratio as well as outlet temperature (operating temperature of pre-reformer) of induced fluid. In addition the model for pre-reformer predicts the effect of input gas temperature on the shift and reforming reactions kinetic. The SOFC developed electrochemical model predicts the effects of electrical load variations on out put gas composition as well as its characteristics. Finally components model are coupled together to conduct a parametric study of the complete cycle. It is found that at the low mixing ratio the pressure variation with the mixing ratio is very sharp but at mixing ratios higher than 1.5 the outlet pressure curve will become smooth. And also it is observed that CH4 mole fraction decreases but H-2 and CO2 mole fractions will increase as the input temperature augments.