Modeling, simulation and analysis of tank thermodynamic behaviors during no-vent LNG bunkering operations

• An analytical model was proposed for no-vent LNG bunkering operations. • A droplet model was developed to quantitatively study vapor condensation and cooling. • LNG bunkering through both top and bottom filling lines were simulated. • Bunkering performance is very sensitive to the supply temperature and droplet size. The bunkering process is an important issue of the operation of liquefied natural gas (LNG) fueled ships. In this paper, an analytical model was developed to predict and investigate the thermodynamic behaviors of marine LNG fuel tanks during no-vent bunkering operations. The complex heat and mass transfer phenomena inside the cryogenic tanks were considered and modeled. A spray droplet model was developed to quantitatively evaluate the vapor condensation and cooling effect in the tank during top spray filling. The validity of the model was confirmed by the measured data on a Norwegian car ferry. The results show that the vapor condensation and cooling at the droplet-vapor interface dominate the top spray filling process, while the vapor compression dominates the bottom filling process. The impact of vapor condensation on the tank pressure during top spray filling is around 2.6 times as large as the vapor cooling. Furthermore, parametric study reveals that the bunkering performance is very sensitive to the LNG supply temperature and droplet diameter.