Electrification of ammonia cracking for on-demand hydrogen production: CFD modeling

Abstract

This paper investigates the design, computational modeling, and thermal optimization of a compact macro-scale ammonia cracking reactor to enable efficient, scalable, and high-conversion hydrogen production through enhanced heat management and non-isothermal kinetic analysis. The non-isothermal behavior of ammonia decomposition in a parallel plates macro-scale reactor is investigated by means of computational fluid dyinamics simulations, focusing on the optimization of the heat distribution to enhance performance and maintain a compact design. This approach addresses industrial need for efficient, zero-carbon hydrogen production from ammonia, and provides practical and scalable design solutions for thermal management in high-throughput endothermic reactions. Kinetic parameters for the reactor were determined based on a commercial catalyst, and simulations were conducted to solve mass and energy balance equations and to model reacting flow properties, including species mole fractions and NH₃ conversion rates. A comprehensive heat transfer analysis was conducted to evaluate temperature gradients in both the heater and the reactor sections, aiming to minimize hot spots and improve internal heat distribution. Results show the optimized heating plates of the system can efficiently provide the required reaction heat, reducing temperature gradients across the system. Increasing the heater length enhanced surface contact and lowered the heat flux, minimizing the formation of hot spots. This optimized approach holds promise for enhancing the ammonia cracking reactor performance for high-throughput hydrogen generation.