Dynamic modeling and analysis of bunkering and pressurization for marine LNG fuel tank

Abstract

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.