Modelling thermosyphon in Star-CCM+

HHK · June 7, 2018, 04:25

Hi all,
I am trying to model a thermosyphon (which is a heat transfer device based on evaporation and condensation processes) using Star-CCM+. The details were taken from this publication
https://www.researchgate.net/publica...d_thermosyphon

I have attached the mesh I have used and the screen shots of models in Star.
The problem I am facing is, phase change does not happen even after 40 seconds of run.
Anybody who has experience on this, please do comment.
I have seen similar threads in the forum but none of them are properly answered.
Thanks in advance.

HHK · June 10, 2018, 06:23

Hi all,

Does anybody know how to model it?
Please post your comments.

me3840 · October 29, 2018, 18:13

Heat pipes are very difficult to model explicitly like this.

You say phase change does not occur, this implies there isn't enough heat to generate the change. Does your model show that the temperature and pressure are sufficient to make a phase change?

HHK · October 29, 2018, 19:38

Hi me3840,
Thank you so much for replying!

Quote:

Originally Posted by me3840

You say phase change does not occur, this implies there isn't enough heat to generate the change. Does your model show that the temperature and pressure are sufficient to make a phase change?

I believe so because all the values I have kept are from literature which includes CFD (in Fluent

) and experiments.

It would be a great help if you can tell me why it usually happens and provide some suggestions.

me3840 · October 30, 2018, 09:31

Merely saying "I applied everything from literature, it should work!" is not a good troubleshooting step :P

You need to look in your model and see if it's generating the thermodynamic conditions for phase change to occur. If it is not, then you may have a problem with the boundary conditions, as those are the only sources of heat. If it is, then there's a problem with how the phase change models are being applied or their inputs are incorrect.

HHK · October 31, 2018, 04:26

Quote:

Originally Posted by me3840

You need to look in your model and see if it's generating the thermodynamic conditions for phase change to occur. If it is not, then you may have a problem with the boundary conditions, as those are the only sources of heat. If it is, then there's a problem with how the phase change models are being applied or their inputs are incorrect.

Thanks me3840,
I will definitely try to debug in this way.

Will update the thread soon.

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October 29, 2018, 18:13		#3
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	Heat pipes are very difficult to model explicitly like this. You say phase change does not occur, this implies there isn't enough heat to generate the change. Does your model show that the temperature and pressure are sufficient to make a phase change?

October 30, 2018, 09:31		#5
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	Merely saying "I applied everything from literature, it should work!" is not a good troubleshooting step :P You need to look in your model and see if it's generating the thermodynamic conditions for phase change to occur. If it is not, then you may have a problem with the boundary conditions, as those are the only sources of heat. If it is, then there's a problem with how the phase change models are being applied or their inputs are incorrect.