hamed razaie - phd.student k.n.toosi university of technology faculty mechanical engineering
masoud ziabasharhagh - associate professor k.n.toosi university of technology /faculty mechanical engineering
mostafa mafi - assistant professor i.k international university /department of mechanical engineering

Environmental problems and lack of energy sources force man to find a clean and sustainable energy. Many attempts have been done for solving this problem through different method. Hydrogen is introduced as effective method and show promising features as an alternative to old fuels. Hydrogen is a very light material and occupies a huge space so need to be liquefied to reach an acceptable density of energy. However the liquefaction processes are really costly and less efficient so more try to improve theefficiency is a necessity. In this study hydrogen liquefaction cycle is investigated through parameter optimization. Effect of higher and lower pressure levels on the major parameters of precooling section of hydrogen liquefaction cycle are investigated. To have a better comparison in any step the precooling cycle is optimized and all the practical limitations are considered. The optimized cycle has improvcd ۵% in the cfficiency with any significant change in the practical limitations

Hydrogen Liquefaction, Precooling, Pressure level, Mixed Refirigerant