Research on compressor utilizing hydrogen storage materials for application in heat treatment facilities

The design of hydrogen compressor utilizing hydrogen storage alloys for application in heat treatment facilities is presented. This compressor working between 0.02 and 3.3 MPa could be an alternative for a mechanical compressor. In laboratory experiments, a model of the hydride compressor was used (scale 1:13). The compressor model uses LaNi4.8Sn0.2 (45 kg) and LaNi4.25Al0.75 (3.5 kg) alloys closed in two separate containers equipped with heat exchangers. The alloys were being heated and cooled by oil flowing through the containers. It was noticed that penetration of hydrogen to the alloy bed situated in the lower part of the containers was not sufficient. The experiments have shown a high efficiency of heat exchangers mounted in the container with LaNi4.8Sn0.2 (finned tubes) and too small efficiency of heat exchangers mounted in the container with LaNi4.25Al0.75 (smooth tubes). The initial research of the stability of alloys subjected to many hydrogen absorption-desorption cycles (207 cycles) was carried out for 0.3–3.3 MPa pressure range (LaNi4.8Sn0.2 at 310–450 K) and 0.02–0.3 MPa (LaNi4.25Al0.75 at 315–410 K). The desorption isotherm for LaNi4.8Sn0.2 at 293 K was also determined.The experiments revealed that energy losses were too high to use the hydride compressor instead of a mechanical compressor in an industrial application. Reducing energy loss would be the most important point of further research.