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

 March 17, 2009, 00:29 #2 New Member   Harshad Join Date: Mar 2009 Posts: 14 Rep Power: 8 I would suggest first calculate heat absorbed by water considereing simple lumped calculations. Model only for flue gas flow, temp, radiation, combustion.... Radiation is allowed for coal particles in CFX. Apply heat trasfer coefficient at the pipe walls. This will take both convective and radiative heat trasfer through wall into account.

 March 17, 2009, 03:34 #3 Member   Lukasz Join Date: Mar 2009 Posts: 64 Rep Power: 8 You mean option b)? Thanks for Your answer. Luk

 March 17, 2009, 04:20 #4 New Member   Harshad Join Date: Mar 2009 Posts: 14 Rep Power: 8 I would suggest heat transfer coefficient instead of specifying temperature because you can tune the heat transfer coefficient so as to get heat flux through pipe walls as calculated by lumped calculations. I have tried similar things.

 March 17, 2009, 04:41 #5 Member   Lukasz Join Date: Mar 2009 Posts: 64 Rep Power: 8 Ok, I understand almost everything: 1) In first calculation I start fire and radiation. I assume a heat transfer coefficient in the pipe wall (I suppose it can be taken for example from literature more or less) and anticipated water temperature. 2) In second calculation only water flows through a pipe. The heat flux (both radiative and conductive) is taken from the previous calculation. I can check if the outlet water temperature has reasonable value with assumed heat flux (from first calculation). If no, I get back to 1) and assume different water temp and/or heat transfer coeff? Thanks You very much, Lukasz

 March 17, 2009, 04:51 #6 New Member   Harshad Join Date: Mar 2009 Posts: 14 Rep Power: 8 I don't know what kind of analysis you are doing. You can tune heat transfer coefficient. Please note that it does't reflect any physical situation like wall deposition.... Just use it as a tuning parameter to get necessary heat flux through wall. If necessary,only then model for water flow. If you are designing for tube length, dia.... For combustion calculations, the wall heat flux is the only necessary part.

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Holidays Main CFD Forum 23 January 9, 2013 04:29 ymg FLUENT 0 October 16, 2008 08:57 Aris FLUENT 0 August 29, 2008 05:44 Luk CFX 2 June 5, 2008 11:31 Amed Main CFD Forum 2 September 25, 2002 04:59

All times are GMT -4. The time now is 17:25.