Critical Assessment and Sub‐System Design of a Solar Tower Simulator for Hydrogen Regeneration by Thermo‐Catalytic Ammonia Cracking

We investigate several critical aspects of a solar tower simulator for thermo‐catalytic ammonia cracking at an ammonia flow rate of 1 kg h −1 . These include (a) assessing the relative impact of optical, conversion, and receiver efficiencies and waste heat recovery (WHR) fraction on the net solar‐to‐hydrogen generation efficiency, (b) designing an optimal WHR and reuse subsystem for the simulator, (c) mitigating the overheating of a 350 We Xe‐short‐arc lamp, and (d) optimizing the catalyst for efficient ammonia decomposition. We conclude that the conversion efficiency has the highest impact on the net solar‐to‐hydrogen generation efficiency. Therminol 55 mass flow rate of 1.75 kg h −1 offers the highest WHR fraction of ~68% and a net solar‐to‐hydrogen efficiency of ~75.8%. A correlation predicts the surface temperature of the Xe‐short‐arc lamp, for airspeed in the range 1.4–5.2 m s −1 , within an uncertainty of about ±5–7%. Effective thermo‐catalytic ammonia decomposition was achieved by precisely tuning the catalyst composition through the selection of an appropriate support and optimized active metal loading. All of these findings will benefit the development and scale‐up of an integrated system.