[haisfa]

Hi,

I have to simulate the change of moisture content of air passing through a fan coil. There is cold water running in a copper tube. The heat of air should be transmitted through aluminum fins and copper tube walls to the water. I successfully simulated the temperature change without considering the moisture content. Therefore the basic settings should be alright. The software version is 2021 R1 student license.

To simulate the change of relative humidity, the multiphase model (mixture) is applied. The related settings are as the following.

Phase:
phase-1: mixture-template (air and water-vapor)
phase-2: water-liquid

Mass transfer:
From phase-2
To phase-1 (h2o)
Mechanism: evaporation-condensation

Boundary conditions:
Inlet:
Air inlet -> phase-2 -> Multiphase: Volume fraction = 0
Water inlet -> phase-2 -> Multiphase: Volume fraction = 1
Outlet:
Air outlet -> phase-2 -> Multiphase: Volume fraction specification method = From neighboring cell
Water outlet -> phase-2 -> Multiphase: Backflow volume fraction = 1

Others are kept as default. After calculation, no condensation occurs even the relative humidity of the air around the tube surface is higher than 100%. I don't know what I missed. I need help.