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aximefu February 24, 2012 01:45

phase change with CFX
I want to simulate the phase change in micro heat pipe with triangle cross section, and I set up a model. I made the configuration as follows:

1water and water vapor are continuous fluids, and they have the constant properties;
2Free surface model;
3heat transfer model: Thermal Energy, turbulence model: BSL Reynolds Stress;
4Surface Tension Coefficient is constant;
5Surface Tension Force: continuum Surface Force, Primary Fluid is water;
6Interphase Transfer: Free Surface ;
7Momentum Transfer: Drag Coefficient
8Mass Transfer: Phase change, phase change model is “Thermal Phase change” and a constant Saturation Temperature will be given;
9Heat Transfer: Two Resistant, vapor side set to be “zero thermal resistance”
Initial conditions: Velocity Type option is Automatic, the temperature set to be ambient temperature, the volume fraction of water is 0.75
Boundary conditions: Heat flux boundary is applied on the face of heat in and heat out, and adiabatic boundary condition is applied on the other surfaces. Wall contact angle is slip wall is chosen for water and water vapor.

The simulation results are shown as follows:

The phenomena that liquid flows from the condenser to the evaporator in the sharp corners, while the vapour moves from the evaporator to the condenser in the centre of the micro heat pipe is not happened. The whole zone in heat pipe is full of water, that is not identical to the overall mass. And interphase mass transfer rate is too small almost close to zero.

So anyone have experience about simulation of phase change point me out the mistake I had made in my simulation? Thanks a lot!

Danial Q March 22, 2012 02:12

Did u solve that problem??

aximefu March 22, 2012 08:49

I haven't work out that problem yet. Are you interested in this problem or somrthing like this?

haider760 March 28, 2012 00:29


I was also trying to use phase change model for mixture flows inside condenser tube but unfortunately the model is extremely disappointing so far!

IPMT rates are actually negligible.

Have you come up with some solution?

Danial Q March 28, 2012 02:28

Hey ! i am also working on some solidification model (including phase change) but unfortunately stuck with some MPF error. still working on it. I am trying fluent for solidification now.:(
u can try" Leap australia"; its some kind of support group for ansys users. just send them ur problem and they would help u to find out any error. it might be helpful for u!!they gave me some suggestions and i ma working on it.

aximefu March 28, 2012 03:38

Tkanks for your information! I will send message to them!

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