A hydrogen-compression system using porous metal hydride pellets of LaNi_(5-x)Al_x

摘要

The objective of this study is to examine the performance of a hydrogen compressor by using recently developed porous metal hydride compact technology exhibiting high thermal conductance. The inlet temperatures of the cooling medium for hydrogen storage (20 and 30℃), the heating medium for compression (60, 70, 80, and 90℃), and the kind of metal hydride (LaNi_5 and LaNi_(4.75)Al_(0.25)) were considered as key parameters. For each condition, transient temperature distributions and compressed pressures were monitored. Results showed that the hydrogen compressor fared better at lower storage temperatures. The research showed that LaNi_(4.75)Al_(0.25) had a faster absorption rate than LaNi_5. In addition, the compression ratio was found to be primarily dependent on the temperature difference between cooling and heating; the compression work and the efficiency of the LaNi_5 reactor were slightly larger than those of the LaNi_(4.75)Al_(0.25) reactor. Under the considered conditions, the maximum work (2.44 kJ) and efficiency (5.91%) occurred when LaNi_5 operated at cooling temperature of 20℃ and heating temperature of 90℃.