Efficient and durable system design for ammonia-fueled solid oxide fuel cells using multiscale multiphysics modeling approach

Abstract

It is crucial to consider all of the scales and underlying physics to design a durable and efficient ammonia-fueled SOFC system. Therefore, a novel multiscale multiphysics modeling approach is used in this study as a design tool to investigate various features of ammonia-fueled SOFC systems, stacks, and cells including performance and nitriding degradation. Different system configurations are designed and influence of anode off-gas recirculation (AOR) and ammonia pre-cracking is investigated. Results indicate the impact of the design changes on efficiency and nitriding degradation. Air flow rate and inlet temperature should be controlled for different configurations to keep the temperature of cells in the stacks inside a desired range. Implementing the AOR showed a considerable improvement in efficiency as for 0 %, 50 %, 70 %, and 90 % AOR rates, system efficiencies are around 53 %, 63 %, 70 %, and 75 %, respectively. To avoid nitriding at the given operating conditions, around 90 % external pre-cracking is required. A system with 90 % of pre-cracking and 90 % AOR is selected as the most efficient and durable system configuration, for the technology at hand. Pressure drops in the system components, particularly on the air side, should be minimized to achieve high efficiency in cases with high ammonia pre-cracking ratios.