A 70 MPa hydrogen-compression system using metal hydrides

The objective of this work was to develop a 70 MPa hydride-based hydrogen compression system. Two-stage compression was adopted with AB2 type alloys as the compression alloys. Ti0.95Zr0.05Cr0.8Mn0.8V0.2Ni0.2 and Ti0.8Zr0.2Cr0.95Fe0.95V0.1 alloys were developed for the compression system. With these two alloys, a 70 MPa two-stage hydride-based hydrogen compression system was designed and built with hot oil as the heat source, and composite materials formed by mixing hydrogen storage alloys with Al fiber were used to prevent hydride bed compaction and to prevent strain accumulation. The experimental results showed that Ti0.95Zr0.05Cr0.8Mn0.8V0.2Ni0.2 and Ti0.8Zr0.2Cr0.95Fe0.95V0.1 alloys could well meet the requirements of compression system. Composite materials formed by mixing hydrogen storage alloys with Al fiber were an effective way to prevent strain accumulation for hydride compression. With cold oil (298 K) and hot oil (423 K) as the cooling and heating sources, the built compression system could convert hydrogen pressure from around 4.0 MPa to over 70 MPa.

► We have developed two hydrogen storage alloys suitable for 70 MPa hydrogen compressors.
► A 70 MPa two-stage hydride-based hydrogen compression system was designed and built with hot oil as the heat source.
► The thermal efficiency of the compression system was calculated.