Sorry for late reply,

I have made some changes and now my model can be highlighted as follows:

Eulerian - evaporation-condensation - saturation temperature 323.15

laminar flow

I changed the material properties to be at operating temperature of 323.15 for both vapor and liquid water. I set the Enthalpy of water as 0 and vapor with the difference between the 2 enthalpies at 323.15 K (after conversion to j/kgmol by multiplying the difference by 18.0152 - the molecular weight of water). I get the material properties from NIST workbook

still rectangular micro-channel with cross section of 50um width, 100um hight and 500 depth. The upper wall is heated with heat = 1e6 W/m^2 (100 W/cm^2)

velocity inlet with liquid entering with speed 0.708 m/s - 323.15 K, and vapor entering with zero velocity and 323.15 K. This 0.708 m/s is equivalent to 700 kg/m.s mass flux

pressure outlet with zero gauge pressure and outlet temperature 323.15 K to avoid super heated vapor

operating conditions - pressure 12352 Pa = saturation pressure, no gravity

methods -> Pressure-velocity coupling - scheme (coupled) - Pressure (Presto) - others set to their defaults - Pseudo transient

initialization - Hybrid - and I patched vapor to fluid body with 0 volume fraction

calculations - time step method (User specified) - pseudo time step (0.001)

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All the convergence curves are below 10^-2, although I have made another check that did not show good result at all

for 10^6 W/m2 I entered on the upper wall of the channel I should be getting 1.049 e-8 kg/s vapor at the outlet according to the following equation:

mass flow rate of vapor * latent heat = 10^6 * area of the upper wall

what I got from the simulation was :

vapor

Mass Flow Rate (kg/s)

-------------------------------- --------------------

inlet -0

outlet -1.2587459e-12

---------------- --------------------

Net -1.2587459e-12

of course 1.2587459e-12 is very far from the theortical value 1.049 e-8

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Here are the convergence curves

Here is the mass integral (mass transfer rate) inside the fluid-body zone

mass transfer rate vs iterations

Any help would be appreciated!