Molecular-kinetic description of heat transfer through a spherical liquid–vapor interface at film boiling

•The Boltzmann kinetic equation by the moment method is solved for the problem of the film boiling on a spherical heating surface.•The analytical expressions for the heat flux is obtained.•The obtained nonlinear relation is transformed into the corresponding flat heating surface formula.•The measured and calculated data on the thin films thickness are in good agreement. Special nonlinear relations can determine the heat flux in a film boiling on a spherical heating surface. They are obtained by transforming the system of moment conservation equations derived from the Boltzmann kinetic equation based on a two-sided Maxwellian distribution approximation. We solve the Boltzmann kinetic equation by the moment method elaborating on the approach of L. Lees for describing thermal conductivity through a gas-filled spherical gap between two impermeable interfaces. The obtained analytical expressions for the heat flux can be used for any value of the Knudsen number.