# condensation

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 February 16, 2010, 09:46 condensation #1 New Member   amirreza hosseini Join Date: Feb 2010 Posts: 5 Rep Power: 9 hi everybody i have to solve a project about ventilation by fluent . in this problem i have a 3D room equippted with chilled ceiling pannels at dew point temperature of humid air in the room. so condensation occurs and liquid water will constituted at the pannels. and this is my requests:how can i model this problem on fluent?(mixture,particle,wet steam) how can i measure mass of water on pannels after a time? if i must use UDF ? if yes, what kind of UDF ? i await your answers. thx alot!

February 17, 2010, 11:53
modeling condensation
#2
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CFDtoy
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model condensation as a mass transfer phenomena (eulerian 2 fluid or mixture approach). Activate source terms in wall and use appropriate UDF to generate source / sink terms. Couple it with volume fraction eqn and you will see mass transfer along the walls (formation of droplets etc) which ever you want to see. Total mass along the walls can be easily extracted and added up to find the liquid generated.

my 2c

/CFDtoy

Quote:
 Originally Posted by amirreza hi everybody i have to solve a project about ventilation by fluent . in this problem i have a 3D room equippted with chilled ceiling pannels at dew point temperature of humid air in the room. so condensation occurs and liquid water will constituted at the pannels. and this is my requests:how can i model this problem on fluent?(mixture,particle,wet steam) how can i measure mass of water on pannels after a time? if i must use UDF ? if yes, what kind of UDF ? i await your answers. thx alot!
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CFDtoy

 February 19, 2010, 17:14 #3 New Member   amirreza hosseini Join Date: Feb 2010 Posts: 5 Rep Power: 9 hi cfdtoy , thank you for your guidance. let me examine and report that.

 February 23, 2010, 09:22 #4 New Member   amirreza hosseini Join Date: Feb 2010 Posts: 5 Rep Power: 9 hi, i have 1 question: can i use the "species transport model" to modelling the humid air(water vapor as a species in air) in this problem ? if YES, then can i use udf to make a species-sink in my wall? Thank you for your attention

 January 26, 2011, 11:00 #5 New Member   Mike_ Join Date: Jan 2011 Posts: 2 Rep Power: 0 amirreza: have you made any progress regarding you condensation problem? Have you created a UDF ? //Mike

 April 24, 2011, 12:20 #6 New Member   amirreza hosseini Join Date: Feb 2010 Posts: 5 Rep Power: 9 Hi, yes, I could calculate the condensation through the cfd programming. I used the correlation of gas diffusion mass transfer in order to calculation the condensation by saturation boundary condition. if you are interested u can find this correlation in the book of "Mass Transfer Operation" by "Robert Treybal." I will be glad to answer more questions. Amirreza

April 29, 2011, 05:47
#7
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Vishal Patil
Join Date: Apr 2011
Location: Pune,India
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Quote:
 Originally Posted by CFDtoy model condensation as a mass transfer phenomena (eulerian 2 fluid or mixture approach). Activate source terms in wall and use appropriate UDF to generate source / sink terms. Couple it with volume fraction eqn and you will see mass transfer along the walls (formation of droplets etc) which ever you want to see. Total mass along the walls can be easily extracted and added up to find the liquid generated. my 2c /CFDtoy
Sir i am working on condensation of R404A refrigerant inside the long circular tube.....at inlet saturated vapor and outlet saturated liquid ......i am using eulerian (k-e mixture ) model.....operating pressure o pa and velocity inlet boundary condition .In this velocity and temp. for both phase has been given.For outlet pressure outlet B.C. is used with o pressure ...I have not used any source term(especially latent heat of vaporisation). only constant wall temp. for tube is used. My solution is not converging and condensation is starting at only some point....am i going in right way .......i am confused .....please please help me....

May 2, 2011, 04:54
#8
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Mike_
Join Date: Jan 2011
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Quote:
 Originally Posted by amirreza Hi, yes, I could calculate the condensation through the cfd programming. I used the correlation of gas diffusion mass transfer in order to calculation the condensation by saturation boundary condition. if you are interested u can find this correlation in the book of "Mass Transfer Operation" by "Robert Treybal." I will be glad to answer more questions. Amirreza
hi again, what was your approach?
(we model a laminar flow problem)
#1 Did you use the species transport model, in that case what settings?
#2 How can i put relative humidity bc at an inlet or domain?
#3 did you write your own udf for the mass transfer of condensate at the boundary, in that case how does it look like?

/Mike

May 18, 2011, 15:52
#9
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Li Huang
Join Date: Jan 2011
Posts: 30
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Quote:
 Originally Posted by mike_cfd hi again, what was your approach? (we model a laminar flow problem) #1 Did you use the species transport model, in that case what settings? #2 How can i put relative humidity bc at an inlet or domain? #3 did you write your own udf for the mass transfer of condensate at the boundary, in that case how does it look like? /Mike
Hi everyone,

I have been following this thread. I am also interested if it's possible to model water condensation/evaporation with Mixture model and species transport model.
Thanks,

Li

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