Model for the Hydrodynamic Boundary Conditions at a Surface Vaporizing under High Temperatures and Pressures

Abstract

The hydrodynamic theorems describing the conservation of energy, momentum, and mass flux are applied on each side of a vaporizing surface, and, further, the mass flux is assumed to be proportional to the difference of the chemical potentials of the vapor and condensed phases. Assuming that heat conduction is negligible, there is also conservation of the total energy (enthalpy and kinetic) of the vapor. From these theorems and assumptions, a simultaneous set of equations is derived which relates the thermodynamic properties of the vapor and condensed phases to the downstream hydrodynamic field and the heating rate of the condensed phase. For small vaporization rates, the set reduces to give the same dependence of the vapor pressure on the vaporization rate as that given by the kinetic calculation of Kucherov and Rikenglaz, but gives a different relationship between the temperature drop across the surface and the vaporization rate than the above authors have calculated.