Effects of Sloshing on the Heat Transfer Coefficient of the Vertical Walls in a Membrane Type LNG Cargo Containment System

In this study, sloshing effects on the heat transfer coefficient of the vertical walls in a membrane type LNG cargo containment system (CCS) were analyzed. To develop correlations of the heat transfer coefficient incorporating sloshing effects, experiments were conducted to measure the heat transfer coefficient of an oscillating vertical plate. Based on experiments, two different correlations were developed which are each applicable to vertical and horizontal oscillations. Using the developed correlations, the heat flow rate penetrated into the vertical walls in KC-1 CCS was investigated under sloshing conditions. The results showed that the penetrated heat flow rate increases with the sloshing speed, which is defined as the product of the sloshing amplitude and the frequency. The maximum increase ratio of the heat flow rate was found to be about 7.5% at the sloshing speed of 10m/s. Also, it was found that the penetrated heat flow rate more increases when the CCS oscillates in the perpendicular direction to the vertical walls, than the parallel direction to the vertical walls. This study suggests that the increase in wall heat transfer coefficients has to be considered when evaluating the boil-off rate of CCSs that are shaking due to sloshing.