Numerical study of the boil-off gas (BOG) generation characteristics in a type C independent liquefied natural gas (LNG) tank under sloshing excitation

Abstract

In this paper, a numerical model considering phase change and external heat leakage is established to study the thermodynamic and hydrodynamic of a type C LNG tank under sinusoidal sloshing excitation. The volume of fluid (VOF) method, coupled with the mesh motion treatment, is adopted to predict the movement of the vapor-liquid interface. The sinusoidal sloshing excitation is realized by a user-defined function (UDF). Compared with related fluid sloshing experiments, the feasibility of the numerical model is verified. The numerical results show that the sloshing excitation has great influences on the thermophysical process and the BOG generation of the LNG tank. The effects of different sloshing frequencies and amplitudes on the thermodynamic characteristics of the LNG tank are studied. In addition, the partial damage of the insulation system is also studied, and it is found that the sloshing has little effect on the critical superheat of the tank wall where the insulation layer is partial damaged, but it will delay the increase of the tank wall temperature. This study is significant to deeply understand the thermal behavior of the LNG sloshing and the characteristics of the BOG generation under sloshing condition during the actual marine transportation of LNG ships.