CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

ONB and CHF prediction in upward water channel with heated walls

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 11, 2018, 01:48
Red face ONB and CHF prediction in upward water channel with heated walls
  #1
New Member
 
ali
Join Date: Dec 2013
Posts: 6
Rep Power: 9
ali_kntu is on a distinguished road
hi dears

i have problem in modeling of upward water channel with heated walls. inlet water temperature is 45 C. heat flux is increases until small bubbles appears.

my problem is bubbles make very late, for example when walls temperature reaches to near 180 C initial bubbles are makes, but in text book it is mentioned that by 10C wall supper heating (from saturation ) ONB is occurs.

and second question:
can CFX predict CHF, how could i calculate CHF(DNBR) in CFX.

Thank you
ali_kntu is offline   Reply With Quote

Old   January 12, 2018, 03:15
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 16,722
Rep Power: 130
ghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the rough
I know what the acronym CFX means, but I do not know all the other acronyms you used. Please define all your acronyms.
ghorrocks is offline   Reply With Quote

Old   January 13, 2018, 05:57
Default Chf ، dnb
  #3
New Member
 
ali
Join Date: Dec 2013
Posts: 6
Rep Power: 9
ali_kntu is on a distinguished road
Onb is onset of nucleate boiling ، and it is occurs when wall temperature is about 10C more than saturation temperature

Chf is critical heat flux which film boiling started

Tanx
ali_kntu is offline   Reply With Quote

Old   January 13, 2018, 17:37
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 16,722
Rep Power: 130
ghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the roughghorrocks is a jewel in the rough
Have you done the CFX tutorial examples on nucleate boiling? They are available in the ANSYS Customer webpage. Note there are many factors you will need to adjust to model your configuration. A critical one is parameters defining the nucleation sites on the heated wall surface, but there are many others.
ghorrocks is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 10:26.