Hyojeong Kim

Existing liquefied petroleum gas (LPG) fuel supply systems are considered for conversion to alternative marine fuels, but the effects of fuel properties on their operating conditions have not been quantified. This study determined how the operating conditions and equipment loads of an existing 200 kW-class LPG fuel supply system change when ammonia, methanol or ethanol is used. With the system configuration kept the same, steady-state simulations were performed with Aspen HYSYS, and the model was compared with operating data of the system with LPG. Under the LPG operating conditions, ammonia did not remain liquid at the high-pressure pump suction (vapor fraction 0.935); raising the low-pressure section from 10 to 11 barg kept it liquid with a pressure margin of 0.57 bar. Methanol and ethanol remained liquid even at a service tank pressure of 2 barg. The pump power scaled with the reciprocal of the liquid density and the heat duties with the liquid heat capacity; the heat duties of ammonia were 1.7–2.1 times those of LPG at equal mass flow rate and 1.6–2.4 times at equal heat input. Similar vapor pressures therefore do not guarantee phase stability, and the results provide property-based guidelines for fuel conversion.

In response to the International Maritime Organization (IMO)’s greenhouse gas reduction targets and the growing demand for decarbonization in the maritime sector, the development of hydrogen-fueled ship technologies has gained increasing attention. Liquid hydrogen (LH₂) is regarded as a promising marine fuel due to its high energy density per unit volume when liquefied at −253 °C, enabling large-scale storage and transportation. However, critical technical challenges remain in cryogenic storage, transfer, vaporization processes, and safety assurance. This study proposes a conceptual pre-standardization framework for land-based evaluation of LH₂ fuel tank and supply systems, supported by preliminary validation using LN₂ surrogate tests. The protocol is established through a reinterpretation of existing international and domestic standards (KGS AC111, ISO/TR 15916, CGA H-3) and adapted to Korean demonstration environments. Test items were categorized into (i) supply performance (flow and pressure), (ii) vaporization and heating performance (temperature), and (iii) safety functions, with acceptance criteria benchmarked against international guidelines. To overcome the significant safety and cost constraints of handling actual LH₂, liquid nitrogen (LN₂) was applied as a surrogate medium to enable preliminary validation under safe and practical conditions, and process simulations are proposed as a future pathway for comprehensive verification. The results highlight not only the application but also the localization and refinement of global standards into a practical protocol for small- to medium-sized ship applications. This protocol is expected to serve as a critical reference for subsequent sea trials and commercialization, thereby contributing to the advancement of eco-friendly marine fuel technologies and strengthening international competitiveness in the hydrogen powered shipping sector.