Wet Surface
This node should be used to model evaporation from and condensation to a solid surface completely covered with liquid water. It adds the evaporation flux to the boundary conditions of Equation 7-3, Equation 7-4, Equation 7-5, or Equation 7-6 of either a Moist Air (Moisture Transport Interface) node or a Hygroscopic Porous Medium node with Equilibrium between liquid and gas phases set to Equilibrium formulation, and computes the corresponding latent heat source to be added in the heat transfer equation.
It can be applied on the exterior boundaries of a domain where either a Moist Air (Moisture Transport Interface) node or a Hygroscopic Porous Medium node is active.
The evaporation flux gevap (SI unit: kg/(m2⋅s)) is defined as:
where Mv is the molar mass of water vapor (SI unit: kg/mol), K is the evaporation rate factor (SI unit: m/s), csat is the saturation concentration of vapor (SI unit: mol/m3), and cv is the vapor concentration (SI unit: mol/m3).
The evaporation flux is accounted for through the moisture flux. On boundaries of a moist air domain it gives:
On boundaries of a porous medium, the moisture flux contains both the vapor diffusive flux and the liquid capillary flux:
The latent heat source qevap (SI unit: W/m2) is obtained by multiplying the evaporation flux by the latent heat of evaporation Lv (SI unit: J/kg):
Wet Surface Settings
Enter a value or expression for the Evaporation rate factor K.
See Moist Surface node for the computation of the amount of liquid water accumulated on a solid surface partially covered with liquid water, due to evaporation and condensation.
When a Heat and Moisture multiphysics coupling node is active, the resulting latent heat source is automatically added as a boundary heat source into the heat transfer equation.
Evaporative Cooling of Water: Application Library path Heat_Transfer_Module/Phase_Change/evaporative_cooling
Location in User Interface
Context Menus
Moisture Transport in Air > Evaporation/Condensation > Wet Surface
Moisture Transport in Building Materials > Evaporation/Condensation > Wet Surface
Equilibrium Moisture Transport in Porous Media > Evaporation/Condensation > Wet Surface
Nonequilibrium Moisture Transport in Porous Media > Evaporation/Condensation > Wet Surface
Ribbon
Physics tab with interface as Moisture Transport in Air, or any version of the Moisture Transport interface selected:
Boundaries > interface > Wet Surface