Massive production of hydrogen with high efficiency, CO 2 free, and cost effectiveness is a critical challenge in the hydrogen economy. Thermochemical cycles are potential methods to produce hydrogen. The iodine–sulfur (IS) process is one such thermochemical cycle. It utilizes clean primary energy sources such as nuclear, solar, and industrial waste heat, and is a promising candidate for large‐scale hydrogen production. A key step in this process, the HI decomposition reaction, significantly impacts the overall thermal efficiency. The reaction is a gas‐phase catalytic reaction, so a packed bed reactor (PBR) is an ideal candidate for this. Various configurations of PBRs are simulated using computational fluid dynamics (CFD) software to optimize the decomposition step. The study first compares external heating versus internal heating strategies and demonstrates that internal heating provides better thermal distribution and enhanced reaction conversion. The study then focuses on different inlet configurations and reveals that a 4‐inlet system outperforms a single inlet setup, offering improved flow uniformity, better heat distribution, and reduced pressure drop, which makes the process more economical while increasing conversion efficiency. Additionally, the study also focuses on the influence of key operating parameters like feed flow rate, feed temperature, and heater temperature on HI conversion. Results obtained from these COMSOL simulations offer valuable insights into the optimal design and operation of HI decomposition reactors. It also provides a theoretical and technical basis for improving the performance and scalability of the IS process in large‐scale hydrogen production.
Bhattacharya et al. (2026) studied this question.