Experimental studies on a micron-copper powder enhanced multi-helical AB5 hydrogen storage reactor: Challenges and pathways to improved design

The first of its kind, a four-helical copper tube structured AB₅-based hydrogen storage reactor, is fabricated based on the author's prior multi-objective optimization method. The reactor employed a 4 × 1.6 mm copper tube and recorded a weight ratio of 0.65. The reactor absorbed 68.82 g of hydrogen at 25 bar, 298 K, and 1.5 lpm in 1582 s with a volumetric storage density of 25.81 kg_H/m³ and thermal power of 114.81 W/kg_h. This study advances a pioneering thermal augmentation strategy, uniquely incorporating 3 % pure micro-copper powder (5 μm size) into the alloy bed. Integrating 3 % copper reduced the absorption time by 27.37 % (to 1149 s) under the same conditions while substantially enhancing thermal power (164.65 W/kg_h, ↑43.4 %). The experimental studies demonstrated that copper powder addition proved the most effective and economical strategy for enhancing heat transfer, all while maintaining the weight ratio. It enhanced thermal power by 43–58 %, reduced absorption time by 27–32 %, and enhanced heat extraction efficiency by 5–6 % across all experimental cases. Moreover, challenges encountered during fabrication and experimentation are analyzed, and an improved design is offered. The improved design, validated and simulated numerically, outperformed the fabricated reactor in weight ratio (↑27.69 %), thermal power (↑20.87 %), and volumetric storage density (6.35 %) at a reduced absorption time (↓13.65 %). The implementation of hybrid thermal energy storage indicated that the levelized energy cost for 10000 absorption cycles, heating ∼4.96 L of water per cycle to 343 K under 298 K, 1.5 lpm, and 25 bar conditions, is $0.26/kWh.