Thermodynamic Optimization of a Monolithic-Type Solid Oxide Fuel Cell

In the presented paper possible design modifications in tubular solid oxide fuel cell (SOFC) geometry are investigated in order to increase its performance. The analysis of entropy generation mechanism is very important to optimize the second-law performance of these energy conversion devices. The use of this technique makes it possible to identify the main irreversibilities, understand their causes and propose changes in the system design and operation. The various contributions to the entropy generation are analyzed separately in order to identify which are the main geometrical parameters to be considered as the independent variables in the optimization procedure. The optimization is applied to a CFD model of the fuel cell which accounts for energy equation, fluid dynamics in the channels and in porous media, current transfer, chemical reactions, electrochemistry and raditive heat transfer. The entropy generation is computed as a post-processed quantity with the data obtained for the CFD model. The geometrical parameters of the fuel cell are modified to minimize the overall entropy generation. Boundary conditions to the CFD model are provided with the aid of a reduced thermal model to take in account stack operating condition.