본 논문은 슬로싱 상태에 놓인 포화 상태 액체수소탱크에서 열 유속 및 BOG(Boil-off gas)의 경향을 다루고 있다. 특히, 액체-기체 간의 침투 및 혼합에 의한 열 교환에 관심을 두었다. 먼저, VOF(Volume of fluid)와 Eulerian 기반의 다상 유동모델로 모형 슬로싱 실험 을 모사하여 압력을 예측하고 계측된 값과 비교하였다. 자유 수면 및 충격 압력 실험 결과와 해석 결과를 비교하였으며, 유체의 속도 예측에서 정확할 수 있음을 간접적으로 증명하였다. 그리고 2차원의 Type-C 원통형 수소탱크를 대상으로 다상열유동해석을 수행하 였다. 이때 포화상태에 놓인 액체 및 기체수소를 가정하고, 해석을 통해 각 상간의 혼합에 의한 열 교환의 수준을 확인하고자 하였다. 단, 상간의 열 교환만을 관심으로 두고 있었으므로 질량전달 및 기화모델은 해석에서 제외하였다. 최종적으로 상의 혼합으로 인해 액 체수소로 유입되는 열 유속의 기여도에 대하여 정리하였다. 또한 액체수소로 유입되는 열 유속과 집중 질량 기반의 간이식을 통해 BOG 발생량 및 경향을 예측하고 분석하였다.

This study was conducted to predict the tendency for heat exchange and boil-off gas (BOG) in a liquefied hydrogen tank under sloshing excitation. First, athe fluid domain excited by sloshing was modeled using a multiphase-thermal flow domain in which liquid hydrogen and hydrogen gas are in the saturated state. Both the the volume of fluid (VOF) and Eulerian-based multi-phase flow methods were applied to validate the accuracy of the pressure prediction. Second, it was indirectly shown that the fluid velocity prediction could be accurate by comparing the free surface and impact pressure from the computational fluid dynamics with those from the experimental results. Thereafter, the heat ingress from the external convective heat flux was reflected on the outer surfaces of the hydrogen tank. Eulerian-based multiphase-heat flow analysis was performed for a two-dimensional Type-C cylindrical hydrogen tank under rotational sloshing motion, and an inflation technique was applied to transform the fluid domain into a computational grid model. The heat exchange and heat flux in the hydrogen liquid-gas mixture were calculated throughout the analysis,, whereas the mass transfer and vaporization models were excluded to account for the pure heat exchange between the liquid and gas in the saturated state. In addition, forced convective heat transfer by sloshing on the inner wall of the tank was not reflected so that the heat exchange in the multiphase flow of liquid and gas could only be considered. Finally, the effect of sloshing on the amount of heat exchange between liquid and gas hydrogen was discussed. Considering the heat ingress into liquid hydrogen according to the presence/absence of a sloshing excitation, the amount of heat flux and BOG were discussed for each filling ratio.

Abstract
1. 서 론
2. 본 론
    2.1 유동 및 열확산 반영방법
    2.2 수치해석 방법
3. 슬로싱 압력 해석 검증
    3.1 슬로싱 실험 조건
    3.2 다상 유동 모델의 개요
    3.3 압력 비교 결과
4. Type-C 액화수소 탱크의 열 유속 예측
    4.1 대상 모델 및 격자
    4.2 슬로싱에 따른 내부 벽면의 대류 열 유속 변화
    4.3 Filling Ratio에 따른 열 유속 예측 결과
5. 결 론
감사의 글
References

• 이진호(인하대학교 조선해양공학과 석사과정) | Jin-Ho Lee (Graduate Student, Department of Naval Architecture and Ocean Engineering, Inha University, Incheon, 22212, Korea)
• 황세윤(인하대학교 조선해양공학과 연구교수) | Se-Yun Hwang (Research Professor, Department of Naval Architecture and Ocean Engineering, Inha University, Incheon, 22212, Korea)
• 이성제(인하대학교 조선해양공학과 박사과정) | Sung-Je Lee (Graduate Student, Department of Naval Architecture and Ocean Engineering, Inha University, Incheon, 22212, Korea)
• 이장현(인하대학교 조선해양공학과 교수) | Jang Hyun Lee (Professor, Department of Naval Architecture and Ocean Engineering, Inha University, Incheon, 22212, Korea) Corresponding Author