Steady condensation process between two flat surfaces

The paper examines steady heat and mass transfer during condensation and evaporation on two flat liquid surfaces bounding a vapor. It is assumed that the evaporated molecules which are detached from the surface have a Maxwellian distribution and a temperature equal to that of the liquid surfaces. This problem is treated on the basis of the nonlinear BGK kinetic equation, which is solved numerically via the discrete ordinate method. Water vapor flow in a wide range of Knudsen numbers determining the rarefaction rate of the vapor, is treated as an example.