شبيه سازي راكتور بستر پرشده جريان شعاعي به منظور بررسي اثر گرمايش بستر كاتاليست بر تجزيه آمونياك

The ammonia decomposition reaction is a key step in the green energy utilization chain, as it alleviates hydrogen storage an‎d transportation challenges while enabling the use of existing energy infrastructure. In this study, a three-dimensional numerical simulation of ammonia decomposition in a radial-flow packed-bed reactor was performed using COMSOL Multiphysics 6.2 to eva‎luate thermal performance an‎d ammonia conversion under various operating conditions. Owing to the endothermic nature of the reaction, the low efficiency of conventional heating systems, an‎d the significant difference between isothermal an‎d adiabatic operation, the non-adiabatic performance of radial-flow reactors with in-bed heating was investigated. The novelty of this work lies in the application of a radial-flow reactor for ammonia decomposition, due to its ability to operate at high gas flow rates with low pressure dro‎p, an‎d in the analysis of an in-bed heating system based on heating tubes arranged parallel to the flow direction. The effects of heating tube arrangement, number of tubes, catalyst particle thermal conductivity, particle size, an‎d tube wall temperature on ammonia conversion were examined. The results show that increasing the number of heating tubes enhances temperature uniformity in the catalyst bed an‎d continuously improves ammonia conversion, increasing from 46.6% under adiabatic conditions to 75.9% at the highest tube density (192 tubes), while increasing the thermal conductivity of catalyst particles from 0.3 to 1 W/(m·K) raised conversion to approximately 89.4%. Furthermore, reducing catalyst particle size an‎d increasing the heating tube wall temperature significantly promoted ammonia conversion, underscoring the importance of thermal management an‎d optimal in-bed heating design in non-adiabatic packed-bed reactors an‎d providing practical guidance for the design an‎d industrial scale-up of radial-flow reactors for ammonia decomposition.

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