Boiling water
 

I am modelling the process that water is the working fluid; and the temperature change is significant. So the material used is the water with variable density. I am looking for the tutorial of CFX that provide the detail how to deal with this kind of problem, for example, something about boiling water. Where can I find it? Thank you very much.

Atit Koonsrisuk

Re: Boiling water
 

Hi Atit,

You can find information about boiling model in Multiphase flow sections of Solver modelling and Solver theory.

You must be, however, using CFX5.6 or CFX4.

With the boiling model - you will not get water with density changing from water to steam density, but you will have water (at constant density or not) evaporating to steam as the second phase.

Matej

Re: Boiling water
 

Dear Matej, Thank you for your answer. Do you know where I can find the case that the temperature of water increasing so much but the phase isn't changed?

Atit

Re: Boiling water
 

Atit,

I do not think I understand your question. Can you, please, describe what are you modelling?

Matej

Re: Boiling water
 

Dear Matej, I am sorry that I did not make myself clear. The working fluid of my case is water. Water is heated and the increasing temperature is enormous. So I want to model the system that density of water can change. Then I want to find an example that model water with variable density. I hope it is clear. Atit

Re: Boiling water
 

Well,

I'm sorry to be so engineer, but can you transform thw word 'enormous' to more quantitative expression? and is the pressure changing?

So you are changing the temperature of water, it is changing the density but is not boiling, water remains saturated, or is there a steam forming? I guess from previous questions you try to solve the problem for some time, are you unsatisied with the results because they are not physical, or they just do not look the way you want them to be?

I think that setting density dependence on temperature and setting the function in CEL should work. If you doubt it you can allways try some strong dependence to see if there is any effect - just to test.The enthalpy should be set to total enthalpy and it should work.

I do not know if this is of any help.

matej