|
[Sponsors] |
April 24, 2016, 16:37 |
Drying process (evaporation in porous)
|
#1 |
New Member
Tomasz
Join Date: Mar 2016
Posts: 6
Rep Power: 9 |
Helo everybody
I trying to model a drying process. Hot air from nozzle come throught porous domain. Porous material (straw) contains water (modeled as morphology- dispersed fluid). To model water evaporation i used tips from Solver modeling guide. It seems that evaporation working corectly. Problem is with water-liquid in straw. When simulation starts after few seconds all water goes out. My question is how to stop/fix water in porous region? I want evaporate it not blow out. |
|
April 24, 2016, 21:37 |
|
#2 |
New Member
Angel Vera Gonzalez
Join Date: Dec 2015
Posts: 1
Rep Power: 0 |
Hi, im interested on drying Model for biomass combustion. Would you be so Nice to share the model or some instructions??
Please!! |
|
April 25, 2016, 21:08 |
|
#3 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
Tomasz - it sounds like your physics is wrong then. Can you post your CCL?
|
|
April 26, 2016, 15:15 |
|
#4 |
New Member
Tomasz
Join Date: Mar 2016
Posts: 6
Rep Power: 9 |
ghorrocks thanks for your interest. CCL in attachment
ceolitzin I used tips from Ansys CFX Solver modeling guide (realise 17.0) chapter: 8.5.4.7.2. Liquid Evaporation Model I only changed morphology for dispersed fluid. I'm not sure is it right for this problem |
|
April 27, 2016, 03:04 |
|
#5 |
Senior Member
Maxim
Join Date: Aug 2015
Location: Germany
Posts: 415
Rep Power: 12 |
we generally don't like to download *.zip files from random people from the internet. You should post your CCL in here directly into an [*CODE] [*/CODE] wrapper (without the *)
|
|
April 27, 2016, 04:44 |
|
#6 |
New Member
Tomasz
Join Date: Mar 2016
Posts: 6
Rep Power: 9 |
Is it okey in .txt file?
I can't use [*CODE] [*/CODE] - too many characters |
|
April 28, 2016, 10:11 |
|
#7 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
I think you need to have a careful think about what you are trying to do here. You appear to be modelling the gas as a air/water vapour mixture, and then a multiphase model with water droplets. Please correct me if I am wrong but I don't think a eularian droplet multiphase model is appropriate to model the evaporation process in this application.
Modelling the detailed physics in this as you are attempting appears very challenging to me. So do you really need the detailed physics? I would consider doing a much simpler additional variable approach where you use an additional variable to track the water content of the straw, and have an empirical model to remove the water based on the local conditions. Then the details of the physics are covered in the empirical model. This sounds far simpler to apply to me. |
|
May 5, 2016, 18:58 |
|
#8 |
New Member
Tomasz
Join Date: Mar 2016
Posts: 6
Rep Power: 9 |
ghorrocks do you know any easier way to model drying proces? I don't need very detailed model. I found this solution in Ansys CFX Solver modeling guide (realise 17.0).
|
|
May 6, 2016, 02:32 |
|
#9 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
The additional variable approach I suggested is very simple.
You need to state what is the important physics in your case before we can recommend a model. Is the change of mass important? Heat gain/loss due to evaporation? Humidification of the air leaving the area? Temperature profiles? etc etc. The more of these things you want to model, the more complex it gets. |
|
May 6, 2016, 09:58 |
|
#10 |
New Member
Tomasz
Join Date: Mar 2016
Posts: 6
Rep Power: 9 |
Most important is get to know water mass change in time. I want to estimate optimal time for drying straw for combustion. In addition i want get temperature profile.
I have a real size empirical model and measurement data to compare with simulation. |
|
May 7, 2016, 01:37 |
|
#11 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
So then I guess that important physics would be:
* evaporation rate versus water content, air humidity and temperature data * specific heat loss/gain due to phase change Do you have this data? The specific heat loss/gain would just be standard water data. But I suspect the evaporation rate one is dependant on the straw material so you will need to provide this data. Do you have it? |
|
May 10, 2016, 18:35 |
|
#12 |
New Member
Tomasz
Join Date: Mar 2016
Posts: 6
Rep Power: 9 |
Ok, I found specific heat loss/gain. Evaporation rate, air humidity and temperature (temperature of hot air? Or straw before heating?) - i can gain this data in experiment. But what next? Could You describe Your idea? Is it include a hot air flow?
|
|
May 10, 2016, 21:53 |
|
#13 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
I would be thinking about using a additional variable to track the water content in the straw, and a multicomponent mixture for the air. You then need to couple the AV to the mixture using source terms.
|
|
February 16, 2018, 15:12 |
Drying of brick (half porous)
|
#14 |
New Member
Rose
Join Date: Feb 2018
Posts: 3
Rep Power: 8 |
Helo everybody
Would this case fit considering the 8-hole brick as a porous medium? because I'm trying to seize this case and I'm not getting it. |
|
February 17, 2018, 06:37 |
|
#15 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
It is important to understand what you are trying to do before we suggest approaches to model it. Please answer the questions on your other thread and we will discuss it there.
__________________
Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum. |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
simulate the drying process | Valpress | FLUENT | 8 | April 25, 2018 11:23 |
The fl process could not be started because of UDF | majid_kamyab | Fluent UDF and Scheme Programming | 6 | December 15, 2015 09:42 |
Drying process | mehdimoradi. | FLUENT | 0 | July 16, 2013 05:26 |
Coupling of drying process and flow simulation | franzdrs | Main CFD Forum | 0 | April 29, 2013 15:11 |
problem in simulating porous drying process | benson621 | ANSYS | 7 | December 16, 2011 15:59 |