Condensing Steam Analysis - What Model Should I Use??

victorz · April 22, 2013, 07:40

Hi all,

My analysis includes two-phase steam flow in a pipe (with 15% steam mass fraction, or 2% volume fraction). At a certain location, cold water is injected into the pipe, so that the steam condenses. The aim of this analysis is to determine the exact location (after the cold water injection) at which all of the steam has condensed into water.

Fluent has a built-in Wet Steam model (available with the density based solver), but it has a limitation of 20% steam mass fraction (according to the Users Guide), while my analysis requires a full condensing of the steam.

Another option is to use a regular multiphase model with pressure based solver (I suppose the Eulerian is the most suitable?), but it requires creating complicated UDF's that model the mass and heat transfer from the vapor to the water.

(1) What would you suggest in such a case? What model is the most suitable?
(2) Can I use the Wet Steam model, disregarding the 20% mass fraction limit?
(3) Are there any tutorials for steam condensing problems?

Thanks a lot in advance!!

dlrobin · April 22, 2013, 23:21

I think you can use UDF to model the phase changing. You can find the UDF file on the Internet

victorz · April 24, 2013, 07:48

Thanks dlrobin!

Can you please refer me to a good condensation UDF?

mhdmk · April 25, 2013, 14:50

hi i'm working on a similar case and i use mixture model. i used the model evaporation-condensation model in fluent but you also need a source term for energy equation but when i run the case with energy source term i cant converge it.i also wrote a udf for both mass transfer and energy source term but when i run it fluent says :
Error: Divergence detected in AMG solver: pressure correction

i haven't anyone help me to fix this .if you want give me your email and i send this udf to you.

Kula · February 2, 2015, 22:37

Hi Mehr,

I am working on steam generation and condensation for a solar still. Can you please share the UDF to me too. pls send the UDF to cfdsekar@gmail.com

Thanks for your help. If i get any breakthrough, will share with you.

Thanks
Kula

Quote:

Originally Posted by mhdmk

hi i'm working on a similar case and i use mixture model. i used the model evaporation-condensation model in fluent but you also need a source term for energy equation but when i run the case with energy source term i cant converge it.i also wrote a udf for both mass transfer and energy source term but when i run it fluent says :
Error: Divergence detected in AMG solver: pressure correction

i haven't anyone help me to fix this .if you want give me your email and i send this udf to you.

Atif ch · November 28, 2016, 23:12

Anyone got UDF file for steam condensation ?

April 22, 2013, 07:40	Condensing Steam Analysis - What Model Should I Use??	#1
victorz New Member Join Date: Sep 2011 Posts: 17 Rep Power: 15	Hi all, My analysis includes two-phase steam flow in a pipe (with 15% steam mass fraction, or 2% volume fraction). At a certain location, cold water is injected into the pipe, so that the steam condenses. The aim of this analysis is to determine the exact location (after the cold water injection) at which all of the steam has condensed into water. Fluent has a built-in Wet Steam model (available with the density based solver), but it has a limitation of 20% steam mass fraction (according to the Users Guide), while my analysis requires a full condensing of the steam. Another option is to use a regular multiphase model with pressure based solver (I suppose the Eulerian is the most suitable?), but it requires creating complicated UDF's that model the mass and heat transfer from the vapor to the water. (1) What would you suggest in such a case? What model is the most suitable? (2) Can I use the Wet Steam model, disregarding the 20% mass fraction limit? (3) Are there any tutorials for steam condensing problems? Thanks a lot in advance!!

November 28, 2016, 23:12	Steam Condensation ANSYS-fluent	#6
Atif ch New Member Atif Join Date: Nov 2016 Posts: 1 Rep Power: 0	Anyone got UDF file for steam condensation ?

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April 22, 2013, 23:21		#2
dlrobin New Member 董生 Join Date: Apr 2013 Posts: 1 Rep Power: 0	I think you can use UDF to model the phase changing. You can find the UDF file on the Internet

April 24, 2013, 07:48		#3
victorz New Member Join Date: Sep 2011 Posts: 17 Rep Power: 15	Thanks dlrobin! Can you please refer me to a good condensation UDF?

April 25, 2013, 14:50		#4
mhdmk New Member mehrdad Join Date: Feb 2011 Posts: 20 Rep Power: 15	hi i'm working on a similar case and i use mixture model. i used the model evaporation-condensation model in fluent but you also need a source term for energy equation but when i run the case with energy source term i cant converge it.i also wrote a udf for both mass transfer and energy source term but when i run it fluent says : Error: Divergence detected in AMG solver: pressure correction i haven't anyone help me to fix this .if you want give me your email and i send this udf to you.