Numerical modeling of flow film boiling in cryogenic chilldown process using the AIAD framework

Flow film boiling plays a dominant role in cryogenic chilldown process, which involves complicated heat transfer and flow regime transition. Nevertheless, existing researches about flow film boiling with cryogenic fluids are relatively limited. In this study, a Computational Fluid Dynamics (CFD) model based on a wall heat flux partition algorithm is built. The AIAD framework implemented in the two-fluid model is employed to appropriately calculate the drag force on the liquid-vapor interfaces. The CFD model is validated by the satisfactory coincidence between the simulated heat fluxes and experimental data in literature. Accordingly, the two-phase interaction on the flow regime and heat transfer is further investigated. The results reveal that the vapor film beneath the bulk liquid becomes thinner due to the drag force on the liquid-vapor interface. In addition, FFT analysis on the pressure drop shows that dominant frequency of the interfacial waves in the tube mainly locates around 2.8 Hz. The normalized intensity indicates that fluctuation becomes more violent with the increase of superheat and inlet liquid flow rate. Finally, comparison between correlations and experimental data indicates that a correlation of heat transfer coefficient considering both film boiling effect and forced convective flow effect needs to be proposed.