Konrad Motylinski

Modeling of SOFC-Based Power Systems

Chapter 1 introduces the topic of solid oxide fuel cells, setting out the principles of operation and the governing equations used to compute the balances. Depending on the level of detail required, these equations can be reduced to discrete forms, can be simplified under certain assumptions or substituted by alternative mathematical descriptions. Some modeling techniques go as far as omitting the equations altogether. Alternative methods are often proposed to predict cell and stack performance and perform mass, energy, and charge balances instead of using a purely analytical approach and the governing equations. This chapter looks at the different modeling approaches and discusses the method which was found to be best suited to system-level studies in SOFC-based power systems. Development of a SOFC-based power units is usually an iterative procedure in which modeling is coupled with a conceptual phase which includes a definition of the design. This chapter will present different modeling methods applicable to SOFC-based power systems. Selected approaches are discussed and evaluated for the purpose of analysis of a micro-CHP unit with SOFCs. It also highlights the main parameters affecting the performance of SOFC stacks.

Computational fluid dynamics analysis of an innovative start-up method of high temperature fuel cells using dynamic 3d model

Abstract The article presents a numerical analysis of an innovative method for starting systems based on high temperature fuel cells. The possibility of preheating the fuel cell stacks from the cold state to the nominal working conditions encounters several limitations related to heat transfer and stability of materials. The lack of rapid and safe start-up methods limits the proliferation of MCFCs and SOFCs. For that reason, an innovative method was developed and verified using the numerical analysis presented in the paper. A dynamic 3D model was developed that enables thermo-fluidic investigations and determination of measures for shortening the preheating time of the high temperature fuel cell stacks. The model was implemented in ANSYS Fluent computational fluid dynamic (CFD) software and was used for verification of the proposed start-up method. The SOFC was chosen as a reference fuel cell technology for the study. Results obtained from the study are presented and discussed.