Impact of Thickness on Direct Ammonia Decomposition in Solid Oxide Fuel Cells, Numerical and Experimental Research

Ammonia is a promising carbon-free hydrogen carrier and can be used as a fuel in energy systems, but often requires proper processing or decomposition into hydrogen and nitrogen in the presence of a catalyst. Due to the nickel-based anode and operating temperatures above 600 °C, solid oxide fuel cells (SOFCs) can be directly fed with NH3 as a fuel - direct-ammonia SOFCs (DA-SOFCs). In this study, the performance of cells with different anode thickness was compared under similar operating conditions for crossflow DA-SOFCs. The experimental results were reproduced in the computational fluid dynamics (CFD) software, OpenFuelCell, in which the source term responsible for internal cracking was introduced. Carried out calculations allowed to determine the distribution of ammonia and temperature in the SOFC anode functional layers. Lowering the operating temperature and cell thickness lead to incomplete conversion of ammonia in the cell.