No abstract

In this paper, a numerical model considering phase change and external heat leakage is established to study the pressure variation and temperature distribution of marine Liquefied Natural Gas (LNG) fuel tanks 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). The feasibility of the numerical model is verified by comparisons with related fluid sloshing experiments. The thermal physical process in the LNG fuel tank under sloshing conditions and the static condition are compared, and the effects of sloshing amplitude and frequency on the pressure and temperature distribution of the tank are also studied. The results show that when the external sloshing excitation frequency is close to the first natural frequency of the LNG fuel tank, the tank pressure will drop rapidly in a short time, resulting in the shutdown of Natural Gas (NG) engine. Meanwhile, the influence of the sloshing excitation on the mass transfer is theoretically analyzed by the definition of the sloshing Nusselt number.

Liquefied natural gas (LNG) is becoming an ideal alternative fuel for vessels because of its environmental and economic advantages. As LNG is a cryogenic fuel stored around -163 °C, the LNG fuel tank is a highly non-equilibrium thermodynamic system especially during bunkering and pressurization processes. The accurate prediction of the thermodynamic behaviors inside the LNG fuel tank is critical for the system design and operation. In this study, a fast and effective analytical model of bunkering and pressurization for marine LNG fuel tank was developed. The Norwegian car ferry MF Korsfjord was chosen as a benchmark case to confirm the validity of the model. The top spray filling process, the pressurization process, and the fuel gas supply process of the MF Korsfjord were simulated. The model prediction showed good agreement with the measured data. Besides, cryogenic liquid sloshing inside the fuel tank was investigated as well. The results showed that the sloshing had a severe impact on the tank pressure, especially when the resonance condition of the tank was met, resulting in the shutdown of gas engines in extreme situations.