A High-Performance Dual-Stage Hydrogen Compressor System Using Ca_0.2Mm_0.8Ni₅ Metal Hydride

Dual stage hydrogen compressor with high pressure compression ability can operate efficiently using geothermal, low temperature solar, waste energy as well as combination of these energy sources. In this study, a dual stage thermal compressor system for hydrogen compression was investigated using three different hydrogen storage materials: LaNi₅, Ca_0.6Mm_0.4Ni₅ and Ca_0.2Mm_0.8Ni₅. Compression ratio of Ca_0.2Mm_0.8Ni₅ was found to be 56% and 14.7% higher than those of LaNi₅ and Ca_0.6Mm_0.4Ni₅ respectively, for single stage thermal compressor system with inlet supply pressure of 600 psig. On the other hand, compression performance of Ca_0.2Mm_0.8Ni₅ was similar to that of LaNi₅ at low supply pressure (e.g. 200 psig) condition. In this paper, a dual stage hydrogen compressor system with LaNi₅ in first stage and Ca_0.2Mm_0.8Ni₅ in second stage is proposed for high pressure hydrogen compression based on the experimental results of single stage system. Results show that 53% higher compression ratio can be attained using dual stage hydrogen compressor when appropriate storage materials are selected for two stages.