Thermal Stress Analysis of a Solid Oxide Fuel Cell Interconnect using a Staggered Tube Bank Geometry

Abstract

In this study, the thermal stress of a 3-D planar solid oxide fuel cell, simulated within COMSOL Multiphysics, is investigated when the inlet boundary conditions of velocity and temperature for the fuel and oxidant are varied. Prior to the 3-D simulation, a 2-D flow study was conducted to investigate the effect the peg size of a staggered bank geometry had on the flow characteristics. It was found that the smallest peg radius of 0.5 mm had the best flow profile in terms of reducing the dead zone wake regions that formed. The 3-D study primarily focused on the thermal stress formation within the interconnect and electrodes of the SOFC. Of the three studied geometries (0.5 mm, 0.75 mm, and 1 mm), the 1 mm had the best von Mises stress distribution in the interconnect. Introducing the fuel and oxidant at 973 K was advantageous over the 1073 K inlet temperature resulting in a lower temperature distribution within the cell. Thermal expansion of the pegs into the electrodes caused local compressive stress around the pegs themselves. The 1 mm peg geometry had compressive stress crossover between adjacent pegs potentially causing local fracture.