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유화롱(HWALONG YOU),최병일(BYUNGIL CHOI),도규형(KYUHYUNG DO),김태훈(TAEHOON KIM),김창현(CHANGHYUN KIM),김민창(MINCHANG KIM),한용식(YONGSHIK HAN) 한국수소및신에너지학회 2023 한국수소 및 신에너지학회논문집 Vol.34 No.6
This study analyzes the cool-down process of liquid hydrogen storage tanks, which have advantages in terms of large-capacity transfer, storage, and utilization as hydrogen demand increases. A hydrogen liquefaction plant is selected for analysis and an efficient tank cooling method is sought by comparing the time required for the cool-down process with the gas consumption in connection with the gassing-up process required for the operation of the liquid hydrogen storage tank. The results of this study can be referred to in the operation process after the initial start-up and maintenance of the hydrogen liquefaction plant.
Design of BOG re-liquefaction system of 20,000 m3 liquid hydrogen carrier
Byeongchang Byeon,Hwalong You,Dongmin Kim,Keun Tae Lee,Mo Se Kim,Gi Dock Kim,Jung Hun Kim,Sang Yoon Lee,Deuk Yong Koh 한국초전도저온학회 2023 한국초전도저온공학회논문지 Vol.25 No.3
This paper presents the design of a re-liquefaction system as a BOG (boil-off gas) handling process in liquid hydrogen transport vessels. The total capacity of the re-liquefaction system was assumed to be 3 ton/day, with a BOR (boil-off rate) of 0.2 %/day inside the cargo. The re-liquefaction cycle was devised using the He-Brayton Cycle, incorporating considerations of BOG capacity and operational stability. The primary components of the system, such as compressors, expanders, and heat exchangers, were selected to meet domestically available specifications. Case studies were conducted based on the specifications of the components to determine the optimal design parameters for the re-liquefaction system. This encompassed variables such as helium mass flow rate, the number of compressors, compressor inlet pressure and compression ratio, as well as the quantity and composition of expanders. Additionally, an analysis of exergy destruction and exergy efficiency was carried out for the components within the system. Remarkably, while previous design studies of BOG re-liquefaction systems for liquid hydrogen vessels were confined to theoretical and analytical realms, this research distinguishes itself by accounting for practical implementation through equipment and system design.
Jeong, Jinyeong,Seo, Suwon,You, Hwalong,Chang, Daejun Elsevier 2018 International journal of hydrogen energy Vol.43 No.7
<P><B>Abstract</B></P> <P>This study proposed a liquefied natural gas (LNG)-liquid hydrogen (LH<SUB>2</SUB>) hybrid propulsion system for a 267,000 m<SUP>3</SUP> LNG carrier to be compliant with the energy efficiency design index (EEDI) requirement for CO<SUB>2</SUB> emissions from ships in the near future and evaluated the system with regard to the aspects of the EEDI, hybrid fuel ratio, installation area, safety, and economics. The system design parameters were adjusted to satisfy the EEDI of Phases 4 and 5, which were less than the current EEDI requirement by 14% and 28%, respectively. The propulsion power of 6 MW should be generated in Phase 4 from hydrogen that accounted for 3% of the total mass of LH<SUB>2</SUB> and LNG fuel. The CO<SUB>2</SUB>-free power generation in Phase 5 was increased to 13 MW, corresponding to 6% of the total fuel mass. The LH<SUB>2</SUB> price was $2.0/kg and $2.4/kg for Phases 4 and 5, respectively, to gain an economic competitiveness against the conventional LNG-based propulsion system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The propulsion system of merchant vessels should be satisfied the enhanced environmental regulations and economics. </LI> <LI> The energy efficiency design index provides the applicable fuel ratios of LNG and LH<SUB>2</SUB> considering the environmental policy. </LI> <LI> The cold energy of LH<SUB>2</SUB> liquefied the BOG of LNG to improve the energy efficiency of the system. </LI> <LI> The life cycle analysis is applied to the economic evaluation for the hybrid propulsion systems. </LI> <LI> The breakeven price of hydrogen fuel for hybrid propulsion system is estimated. </LI> </UL> </P>
Numerical and experimental study of a plate-stiffened prismatic pressure vessel
Choi, Younseok,Ahn, Junkeon,You, Hwalong,Jo, Choonghee,Cho, Younghee,Noh, Yeelyong,Chang, Daejun,Chung, Hyun,Bergan, På,l G. Elsevier 2018 Ocean engineering Vol.164 No.-
<P><B>Abstract</B></P> <P>This study evaluates the structural feasibility of a prismatic pressure vessel using strength assessments. A prismatic pressure vessel, which differs from a cylindrical or spherical pressure vessel, is proposed. A prismatic pressure vessel can be used to ship liquefied gas. A prototype of the prismatic pressure vessel was designed, manufactured and tested in accordance with the ASME Boiler and Pressure Vessel Code. Its design uses the “design-by-analysis” method, including protection against plastic collapse. The prototype of the prismatic pressure vessel uses typical construction materials considering their linear elastic and nonlinear plastic behaviors. The vulnerable components of the structure were obtained through numerical analysis using the finite element method. A pressure test with strain gauges was conducted, and the results demonstrate the feasibility of the prismatic pressure vessel as a suitable vessel for high-pressure fluids with high volume efficiencies. The prismatic pressure vessel has potential for general applicability in the shipping of liquefied gas.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This study evaluates the structural feasibility of a prismatic pressure vessel using strength assessments. </LI> <LI> The structural feasibility of a prismatic pressure vessel was demonstrated through numerical and experimental. </LI> <LI> The proposed prototype pressure vessel can be used for real pressure vessel without any failure occur during operation. </LI> </UL> </P>