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fkonias August 28, 2008 08:50

droplet condensation
 
Hi all! I' m trying to perform a droplet condensation simulation in a steam turbine, but I encounter some problems in pre set-up, with the materials choice, mixtures, phase change, libraries etc. I'm using the ansys cfx solver modeling guide but it is not adequate. Were can I find a relevant tutorial?

Thank you F.Konias


fkonias August 30, 2008 13:57

Re: droplet condensation
 
In the guide it is mentioned that I have to choose vapor, liquid and homogeneous binary mixture to define saturation properties. Dose this mean, for example, that in the domain/material list I have to use all three steam3l, steam3v, steam3lv (items that I found in C:\CFX\Ansys Inc\v110\CFX\etc\materials-extra\MATERIALS-iapws.ccl)? If I try to do that, I encounter many problems in set up and error messages.

Kumar August 31, 2008 03:33

Re: droplet condensation
 
You can use H20Rkv,H2oRKl combination from Redlich kwong materials (uses Redlich-Kwong eqn of state).

In material selection use H20Rk which will be HBM of liq and vapor.You have to select droplet condensation model or Phase change model to solve for condensation.

fkonias August 31, 2008 08:13

Re: droplet condensation
 
Thank you for your reply, but I still have a problem.

In domain / general options / fluids list, I used all three: H2ORkl, H2ORkv and H2ORkvl

Domain / fluid models / multiphase options / homogeneous model: active

Domail/fluid details / H2ORKl / morphology / droplets with phase change

/ H2ORKl / heat transfer / small droplet temperature

/ H2ORKv / morphology / continuous fluid

/ H2ORKv / heat transfer / total energy

/ H2ORKvl / morphology / droplets with phase change

/ H2ORKvl / heat transfer / small droplet temperature

/ H2ORKvl / component details / H2ORkl / equilibrium constraint

/ H2ORkv / equilibrium fraction

Domain / fluid pairs / H2ORkl-H2ORkv / interphase transfer / particle model

/ heat transfer / small droplets

/ mass transfer / phase change / small droplets

/ H2ORkv-H2ORkvl / same all

I have the error: The Thermal Phase Change model has been activated for the fluid pair 'H2ORKv | H2ORKvl', but Saturation Temperature details have not been set. Please set it either on the Fluid Pair form or using a Homogeneous Binary Mixture.


fkonias September 2, 2008 03:18

Re: droplet condensation
 
some help please! what do i do wrong? what else do i have to set?

Pankaj September 2, 2008 07:52

Re: droplet condensation
 
take Vapor,liq and HBM. HBM is material defn with liq and vapor. then define their saturation temp in material definition only.

Else in Thermal Phase change option of Mass Transfer,you can define Saturation temp.

fkonias September 2, 2008 11:04

Re: droplet condensation
 
Thank you for making it clear that I have to use all three. When you say "then define their saturation temp in material definition only", what do you mean…? The CCL library? I also found where I can give a value for saturation temperature. And that is only if I use "Thermal Energy" for HBM's heat transfer model. But even that way how can I define it when there is no expression that gives saturation temperature as a function of pressure? Shouldn't that info about saturation temperature be already defined in the CCL library for the material?

Fotis


HekLeR September 9, 2008 22:46

Re: droplet condensation
 
Using all 3 materials is wrong as that would be a 3 phase problem.

You want a two phase problem so just pick the vapour and liquid . You only need to have the HBM in the CCL libarary so the solver is told how to compute saturation properties.

haghshenasfard February 28, 2010 12:13

you should hust consider vapor and liquid, then in the material, defina a hbm


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