Development of a condensing-type hydrogen liquefaction system for improving cooling efficiency and long-term storage

Abstract

In this study, the experimental investigations for production of liquid hydrogen were conducted using a manufactured condensing-type hydrogen liquefaction device. A direct-cooling type hydrogen liquefier was designed, fabricated, and tested using a commercially available cryo-coolers, heat pipe, ortho-para converter, LN2 shield, and LN2 pre-cooler. In order to effectively carry out the experimental investigations in the presence of two cryo-coolers and LN2 shield in addition to the small-scale liquefaction system, this study introduced the new experimental system based on the cryogenic techniques. The production of liquid hydrogen could be achieved just by controlling the temperature and pressure inside the storage vessel. The cooling time of the vessel was reduced by approximately 100 min using new experimental system. The total time required to produce the same amount of liquid hydrogen, around 20L, was reduced by approximately 200 min. The experiments successfully demonstrated the liquefaction of hydrogen gas in the vessel at a rate of approximately 3.5L/h, corresponding to a level meter reading of 14.5 cm (6.95 % of the vessel's height). Therefore, the cooling time of the vessel and the total time required for liquid hydrogen production were found to be significantly influenced by the gas used to cool the initial container and the presence of LN2 shield.