The Investigation of Ca0.6Mm0.4Ni5 for Use in a High Pressure Metal Hydride Hydrogen Compressor

Abstract

The research performed here consisted of the design, construction, and testing of a dual stage metal hydride hydrogen compression system intended to be used with lower grade geothermal or waste energy sources. The metal hydrides used in this study were LaNi5 and Ca0.6Mm0.4Ni5. A FTT model was also developed and the model proved useful in determining how the compression results and energy requirements for the system change with variations in the system parameters. Two single stage hydrogen reactors were also designed and constructed in order to study the compression abilities of the Ca0.6Mm0.4Ni5. The single stage compression results showed that the Ca0.6Mm0.4Ni5 produced maximum compression ratios when higher heating bath temperatures were used. The maximum compression ratio obtained from the single stage Ca0.6Mm0.4Ni5 system was approximately 8, which produced an output pressure of 1,200 psig from an initial supply pressure of 150 psig and a heating bath temperature of 90oC. It was observed that as the supply pressures increase, the final output pressure of the hydrogen also increased, but the compression ratios do not always follow the upward trend. Dual stage system results showed a final compression ratio of approximately 12 when using cooling and heating temperatures of 10oC and 90oC, respectively. The final output pressures and compression ratios were found to follow an upward trend when increasing the heating bath temperatures. It can be concluded from the experimental results, that though the dual stage hydrogen compression system has room for improvement, it is an effective way of compressing the hydrogen from low initial pressures while using low grade energy sources.