FEA analysis and modelling of thermal stress in SOFCs

Schlegl, Harald and Dawson, Richard James (2016) FEA analysis and modelling of thermal stress in SOFCs. In: Proceedings of 12th European SOFC & SOE Forum 2016. UNSPECIFIED, pp. 109-119. ISBN 9783905592214

Abstract

Durability and reliability of anode supported SOFC stacks have proven unsatisfactory in large scale trials, showing rapid failure, thermal cycling intolerance and step change in electrochemical performance most likely related to mechanical issues. Monitoring and understanding the mechanical conditions in the stack especially during temperature changes can lead to improvements of the design and of the operating regime targeting maximum durability. Within this project modelling and simulation of thermal stresses within the different parts of the cells and the stack and the validation of this models play a key role and were performed in this work. The modelling and simulation of stress and strain have been carried out using the FEA software AbaqusTM. Model variations documented the importance of exact knowledge of material properties like Young’s modulus, Poisson’s ratio, thermal expansion coefficient, thermal conductivity and creep viscosity. The benefit of literature data for these properties is limited by the fact that all these properties are highly dependent on the composition of materials but also on details of the fabrication process like mixing, fabrication technique and sintering temperature and duration. The work presented here is an investigation into the modelling techniques which can be most efficiently applied to represent anode supported solid oxide fuel cells and demonstrates the temperature gradient and constraint on the stresses experienced in a typical design. The work described in this paper is part of a project with the title “Noveld iagnostic tools and techniques for monitoring and control of SOFC stacks – understanding mechanical and structural change” and is a collaboration with Loughborough University and Imperial College in the UK and the POSTECH institute of new and renewable energy, the Korea Institute of Energy Research (KIER) and Hankook Oil in Korea.