Study of evaporation and condensation problems by kinetic theory, volume 41, no. 5
Abstract
The halfspace evaporation and condensation problem is investigated by using the linearized BGK model equation and the finite element method. Numerical predictions of microscopic and macroscopic temperature and density slip coefficients based upon the finite element method are compared with alternative numerical results. The method is applied to the twosurface evaporation and condensation problem to obtain the density and temperature distributions in the vapor phase and the mass flux from the high temperature surface to the low one for the various inverse Knudsen numbers. The negative temperature gradient in the vapor phase between the two surfaces is observed in some particular conditions and explained from the kinetic theory viewpoint. Furthermore, by employing the finite element method to the twosurface evaporation and condensation problem in the presence of noncondensable gas, the effects of the noncondensable gas on the mass flux and on the negative temperature gradient are investigated. For the description of this problem, the linearized GK model equations are used. As a result, it is found that the presence of noncondensable gas plays a decisive role in retarding the mass flow rates and makes the occurrence of the negative temperature gradient difficult.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 May 1976
 Bibcode:
 1976STIN...7712330M
 Keywords:

 Condensing;
 Evaporation;
 Kinetic Theory;
 Density Distribution;
 Finite Element Method;
 Half Spaces;
 Mass Flow;
 Mathematical Models;
 Temperature Distribution;
 Fluid Mechanics and Heat Transfer