Sublimation and deposition at a solid sphere in the presence of a non-condensable gas

The sublimation/deposition process at a solid sphere of argon, or krypton, into its vapor in the presence of helium as a background gas is modeled applying the McCormack model for the linearized Boltzmann equation. The mass and energy flow rates from the sphere are expressed in terms of the kinetic coefficients following the formalism of non-equilibrium thermodynamics. The kinetic coefficients are calculated over a wide range of rarefaction parameter covering the free-molecular, transitional and near viscous regimes. Several values of the mole fraction of helium in the mixture are considered. To assess the influence of the interatomic interaction potential on the kinetic coefficients, the calculations are carried out with the hard-spheres model and ab-initio potentials. It is shown that some kinetic coefficients are significantly sensitive to the potential. Profiles of the macroscopic parameters such as temperature, pressure and mole fraction are provided for two reference temperatures, 50 K and 70 K. The phenomenon of negative temperature gradient is discussed. • Sublimation and deposition at a solid sphere of argon/krypton immersed in helium. • Kinetics and thermodynamics of mass and energy exchange at a gas-solid interface. • Effect of atomic potential on the kinetic coefficients: hard-spheres and ab-initio. • Effect of rarefaction, chemical composition, and temperature on mass and heat fluxes.