ESTIMATION OF SPATIAL TEMPERATURE DISTRIBUTION IN CO-FLOW PLANAR SOLID OXIDE FUEL CELLS 1 Handa Xi Jing Sun ∗ Jian Chen Email: xih@umich.edu Email: jingsun@umich.edu Email: jianc@umich.edu Department of Naval Architecture and Marine Engineering University of Michigan Ann Arbor, Michigan 48109 ABSTRACT Significant temperature distribution has been identified in planar Solid Oxide Fuel Cells (SOFCs) during both steady state and transient operations. In order to ensure the material stability and device protection, the maximum temperature and tempera- ture gradient have to be closely monitored and securely main- tained below certain limits. In practical implementation, how- ever, direct measurement of the temperature distribution inside the SOFC is difficult and costly. In this paper, an observer is de- signed and the corresponding performance is analyzed for esti- mating the temperature distribution in the co-flow planar SOFC. To facilitate the observer design, we introduce a reduced-order nonlinear SOFC model that is obtained based on the high-order detailed model derived in our previous work. Using three eas- ily accessible measurements, namely the stack voltage and the temperatures of the solid structure at the entrance and exit of the SOFC, the observer designed based on the low order model can effectively estimate the temperature profile during both steady- state and transient operations. Model-based analysis and simula- tion results are presented to demonstrate the performance of the estimation scheme and to provide design guidelines. NOMENCLATURE C s molar concentration of species s (mol /m 3 ) ∗ Corresponding author. Ph.: (734)-615-8061, Fax: (734)-936-8820. 1 This research is supported in part by Department of Navy (through Office of Naval Research) under grant N00014-06-1-0209 and in part by the Department of Army (through Scientific Service Program) under TCN-05158. I electrical current load (A) N molar flow rate (mol /s) T temperature (K) ∇T temperature gradient (K/cm) U stack operating voltage of the fuel cell stack (V) Subscript: I interconnector PEN PEN structure a air bulk flow airC air flow to CPOX airS air flow to SOFC cathode cpox Catalytic Partial Oxidation reformer f fuel bulk flow s a species in the air flow s f species in the fuel flow sol solid structure in SOFC Superscript: cpox Catalytic Partial Oxidation reformer j the jth discretization unit 1 INTRODUCTION Solid Oxide Fuel Cell (SOFC) provides a promising alter- native energy conversion solution for both stationary and mobile applications. Among different types of SOFCs, planar SOFCs are appealing for their relatively higher power density and effi- ciency. While substantial progress has been made on the planar SOFC technology development, many technical issues are yet to 1 Copyright c  2007 by ASME Proceedings of IMECE2007 2007 ASME International Mechanical Engineering Congress and Exposition November 11-15, 2007, Seattle, Washington, USA IMECE2007-43397