Flow analysis and geometry optimization of an integrated ammonia decomposition-combustion reactor through CFD Modeling

Ammonia, one of the hydrogen compounds, has gained attention as a hydrogen carrier due to its ease of liquefaction, high storage capacity, and environmental friendliness. Ammonia can also be utilized as a direct fuel in some fuel cells. However, it is necessary to consider a system with an ammonia reformer (cracker) because the performance of the fuel cell is significantly improved when the ammonia is pretreated (cracked) rather than directly injected. In order to improve the efficiency of the ammonia reformer, this study analyzes a system in which the off-gas from the fuel cell is reused in the combustor and the heat generated through combustion is utilized for reforming. The internal flow and combustion reactions are simulated by modeling the integrated ammonia reformer and combustor using Computational Fluid Dynamics. Based on this, the optimal operating conditions and reactor geometry are derived to improve ammonia reforming efficiency, achieve a uniform internal temperature, and reduce NOx emissions. The reformer system developed through the results of this study is expected to provide insights for ammonia-based fuel cell system design and operation strategies.