In this study, we have identified the Intermediate Fluid Vaporizer (IFV) as a viable option for large-scale liquefied hydrogen vaporization, given its ability to effectively utilize the cold-heat of the liquefied hydrogen and maintain continuous and stable vaporization. The ultimate goal of this research and development is to introduce hydrogen power generation in order to achieve carbon neutrality in the future and establish a stable supply system to meet the growing demand. To lay the groundwork for the development of a larger IFV, we manufactured and tested a small prototype of this cold-heat recovery type liquefied hydrogen vaporizer, with the aim of acquiring heat transfer performance and mechanical data. Our results demonstrate that the targeted performances, including the volume and temperature of vaporized gas, as well as the temperature of extracted circulating water, were stably achieved. These efforts represent an important step towards establishing a sustainable and efficient hydrogen power generation system.

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Mechanical plating has been attracting attention in recent years as one of the surface treatment methods that can extend the lifetime of metal products. This technique utilizes kinetic energy generated by striking a plating alloy particles at high speed to adhere them to surface of targeted steel object and form a protective film. Since it is a dry-type plating process conducted at room temperature, there are various advantages over conventional zinc coating methods. In this study, the effectiveness of mechanical plating treatment and the mechanism of improving corrosion resistance were investigated. As first step, the corrosion resistance of the alloy powder itself used as a raw material for mechanical plating was evaluated, indicating that the oxygen consumption rate of Zn-Al alloy powders soaked in salt solution was much slower than that of iron powders, and strongly affected by the alloy composition. Furthermore, it was found through the long-term saltwater immersion test and electrochemical evaluation that a corrosion product film of zinc represented good protective performance in the case of applying sufficient mechanical plating treatment. In addition, even better corrosion resistance was obtained when the mechanical plating treatment was conducted as a pretreatment of baked zinc flake coating.

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