Evolution of liquid–vapour interface during film boiling on sphere

Abstract

The dynamics of the liquid–vapour interface during stable liquid film boiling on a spherical heater is described by formulating a complete system of equations. The dynamics of the interface surface is analysed using the Rayleigh equation considering the non-equilibrium effects near the vapour–liquid interface in the boundary conditions. Heat transfer in the vapour phase is determined by the thermal conductivity and radiation and that in liquid is described by solving the unsteady thermal conductivity equation. The closed mathematical description is reduced to a system of ordinary differential equations with corresponding initial and boundary conditions under certain assumptions. For high efficiency liquid heat transfer cases, the system of equations can be simplified owing to zero mass flux across the interface. Finally, the system of equations is solved for sub-cooled water and superfluid helium; the corresponding temporal dependences of the vapour films radiuses are presented.The aim of this work is to propose a method for calculating the evolution of the vapour film during film boiling of highly thermally conductive and subcooled liquids, taking into account the molecular-kinetic features of heat and mass transfer processes on the liquid-vapour interfaces.