conjugate heat transfer with phase change

mogoko · March 22, 2011, 11:53

Hi to all,
I'm simulating conjugate heat transfer with phase change. A cold fluid flows in outer pipe, and a hot fluid flows in inner pipe, a solid domain conducts the heat flow between them. The cold fluid will be heated to evaporate.
Both the inlet velocities are quite low, so I set the flow as laminar.
However, the solution couldn't come to convergence.
Then I tried to set the flow as turbulence, the solution could convergence well, but there was a new problem that the heat transfer solution looked bad. The cold fluid could not evaporate however I changed both the inlet conditions. And the monitor which I set before indeed kept at an invariant liquid volume fraction value of 1.
What the cause of these problems? Mesh? Phase change model?
Thank..

ghorrocks · March 22, 2011, 22:34

Sounds like you should build up your model one bit at a time. You have a number of complex systems and you need to get them working well by themselves before they will work together.

I would model the evaporating cold fluid by itself and make sure that works reliably before I added CHT and the hot fluid.

mogoko · March 23, 2011, 12:25

Um, before this I've made a simple simulation with evaporation only. I tried both particle model and mixture model which both came to a good solution. Then I made a conjugate heat transfer simulation without phase change, it also performed well. However, once I conjugated fluid and solid, problems came out.

March 22, 2011, 11:53	conjugate heat transfer with phase change	#1
mogoko New Member Neil Yang Join Date: Mar 2011 Posts: 6 Rep Power: 15	Hi to all, I'm simulating conjugate heat transfer with phase change. A cold fluid flows in outer pipe, and a hot fluid flows in inner pipe, a solid domain conducts the heat flow between them. The cold fluid will be heated to evaporate. Both the inlet velocities are quite low, so I set the flow as laminar. However, the solution couldn't come to convergence. Then I tried to set the flow as turbulence, the solution could convergence well, but there was a new problem that the heat transfer solution looked bad. The cold fluid could not evaporate however I changed both the inlet conditions. And the monitor which I set before indeed kept at an invariant liquid volume fraction value of 1. What the cause of these problems? Mesh? Phase change model? Thank..

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March 22, 2011, 22:34		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	Sounds like you should build up your model one bit at a time. You have a number of complex systems and you need to get them working well by themselves before they will work together. I would model the evaporating cold fluid by itself and make sure that works reliably before I added CHT and the hot fluid.

March 23, 2011, 12:25		#3
mogoko New Member Neil Yang Join Date: Mar 2011 Posts: 6 Rep Power: 15	Um, before this I've made a simple simulation with evaporation only. I tried both particle model and mixture model which both came to a good solution. Then I made a conjugate heat transfer simulation without phase change, it also performed well. However, once I conjugated fluid and solid, problems came out.