Modeling Coupled Heat and Mass Transfer upon Film Condensation

A mathematical model of film condensation is constructed which is obtained based on the equations for the conservation of mass, momentum, and energy for a heat-transfer fluid in the limited region of the condensate film and gas phase flowing down the surface of the wall of a heat exchanger in a two-dimensional setting. Equations for conserving the momentum of this model take into account the change in the physical properties of the heat-transfer fluid and condensate film depending on temperature. The boundary conditions of coupling are written for the regions on the inner wall of the flow range of the heat-transfer fluid and outer wall along which the condensate film flows, as well as at the film–gas interface. The boundary problem is solved by approximate and numerical methods, together with the condition for determining the unknown thickness of the film for different settings of the thermodynamic problem. Computational and physical experiments are conducted to study the main parameters and regularities of the process.