Dynamic–to–Static Surface–Area–Ratio Scaling of Sloshing–Induced Boil–Off Amplification in a Partially Filled Rectangular Tank

Sloshing can increase boil–off gas (BOG) generation in partially filled tanks by renewing near – wall thermal boundary layers and deforming the liquid–vapor interface. This study quantifies the corresponding boil–off – rate (BOR) amplification in a rectangular water–steam system maintained at a nominal pressure of 2.0 bar, with saturation and outer – boundary temperatures of 120 and 160 °C, respectively. A volume – of – fluid (VOF) unsteady Reynolds – averaged Navier–Stokes (URANS) solver is coupled with conjugate heat conduction through a modeled solid insulation layer, Rohsenow – type weak nucleate wall boiling, and a volumetric interfacial evaporation closure. Hydrodynamics are benchmarked against an isothermal sway – excited rectangular – tank experiment, and static heat ingress is assessed using Nusselt – number comparisons and boiling – regime checks. Twenty forced – sway cases cover filling ratios of 20–80% and excitation periods of 0.9–1.7 s. Near the dominant sloshing response, the time – averaged BOR reaches 2.8–4.0 times the static value, while the longest – period cases yield amplification factors of 1.09–1.57. The wetted – wall pathway contributes 62–93% of the dynamic BOR. Dynamic – to – static wetted – wall and free – surface area ratios organize the observed BOR amplification, and a ridge – regularized surrogate achieves R 2 = 0.894 and MAPE = 11.5% within the investigated design space.