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

Condensation in a closed thermosyphon??? (heat pipe, evaporation-condensation))

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 20, 2014, 19:59
Default Condensation in a closed thermosyphon??? (heat pipe, evaporation-condensation))
  #1
New Member
 
Xiaobing Zhang
Join Date: Apr 2014
Posts: 12
Rep Power: 12
xiaobingwill is on a distinguished road
Hello,

I'm modeling phase change flow in a closed thermosyphon. Now my status is having evaporation in my evaporator. But little condensation is found in the cold part. The following pics are my results.

I calculated 200s already, but condensation is still very small.

Any guidance or help will be appreciated.

Thanks,
Xiaobing

Limited condensation happens in the condenser.

Limited condensation happens in the condenser.

Evaporation is good.
xiaobingwill is offline   Reply With Quote

Old   April 7, 2015, 16:19
Default Udf
  #2
Member
 
Muhammed Asmail
Join Date: Nov 2009
Location: Iraq
Posts: 43
Rep Power: 17
Muhammed_iraq is on a distinguished road
did you use UDF for heat and mass transfer ??
i am not get on condensation ??!!!
i do not know why?
Muhammed_iraq is offline   Reply With Quote

Old   December 12, 2015, 23:35
Default evaporation condensation in fluent
  #3
Member
 
Ram Kumar Pal
Join Date: Apr 2015
Posts: 38
Rep Power: 11
rampal is on a distinguished road
Hello friends, I have written UDF for phase change in thermosyphon, boiling is happening inside evaporator but there is no condensation inside condenser, I'm confused why this error is happening. I'm writing UDF below, please notify me what is the error in UDF.

#include "udf.h"
#include "sg_mphase.h"
#include "mem.h"
#include "metric.h"
#include "flow.h"
#include "sg.h"
#define T_SAT 373
#define LAT_HT 2455e3
DEFINE_SOURCE(vap_src,cell,pri_th,dS,eqn)
{
real m_dot_v;
Thread *mix_th, *sec_th;
mix_th = THREAD_SUPER_THREAD(pri_th);
sec_th = THREAD_SUB_THREAD(mix_th,1);
/*m_dot_v=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_v = 0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = 0.0;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_v = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
}
return m_dot_v;
}
DEFINE_SOURCE(liq_src,cell,sec_th,dS,eqn)
{
real m_dot_l;
Thread *mix_th, *pri_th;
mix_th = THREAD_SUPER_THREAD(sec_th);
pri_th = THREAD_SUB_THREAD(mix_th,0);
/*m_dot_l=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_l = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_R(cell,sec_th)*(C_T(cell,mix_th)-T_SAT)/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_l = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] =0.0;
}
return m_dot_l;
}
DEFINE_SOURCE(enrg_src,cell,mix_th,dS,eqn)
{
real enrg_dot;
Thread *pri_th, *sec_th;
pri_th = THREAD_SUB_THREAD(mix_th,0);
sec_th = THREAD_SUB_THREAD(mix_th,1);
if (C_T(cell,mix_th)>T_SAT)
{
enrg_dot = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT*(C_ T(cell,mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
enrg_dot = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*LAT_HT*(T_ SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*LAT_HT/T_SAT;
}
return enrg_dot;
}
rampal is offline   Reply With Quote

Old   December 14, 2015, 10:22
Default Udf
  #4
Member
 
Muhammed Asmail
Join Date: Nov 2009
Location: Iraq
Posts: 43
Rep Power: 17
Muhammed_iraq is on a distinguished road
Dear rampal

your Ansys-Fluent is original version??
I mean original from the company no commercial that it is bought from the market
case of heat pipe is very complex and it needs original license and the condensation will not appear to you if the Ansys not original version as it happened with me through 8 months and i did not get result
Ansys can solve simple cases if it is not original version but heat pipe is complex case and it needs original version
i hope that you understand me
many thanks
Mohammed













Quote:
Originally Posted by rampal View Post
Hello friends, I have written UDF for phase change in thermosyphon, boiling is happening inside evaporator but there is no condensation inside condenser, I'm confused why this error is happening. I'm writing UDF below, please notify me what is the error in UDF.

#include "udf.h"
#include "sg_mphase.h"
#include "mem.h"
#include "metric.h"
#include "flow.h"
#include "sg.h"
#define T_SAT 373
#define LAT_HT 2455e3
DEFINE_SOURCE(vap_src,cell,pri_th,dS,eqn)
{
real m_dot_v;
Thread *mix_th, *sec_th;
mix_th = THREAD_SUPER_THREAD(pri_th);
sec_th = THREAD_SUB_THREAD(mix_th,1);
/*m_dot_v=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_v = 0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = 0.0;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_v = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
}
return m_dot_v;
}
DEFINE_SOURCE(liq_src,cell,sec_th,dS,eqn)
{
real m_dot_l;
Thread *mix_th, *pri_th;
mix_th = THREAD_SUPER_THREAD(sec_th);
pri_th = THREAD_SUB_THREAD(mix_th,0);
/*m_dot_l=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_l = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_R(cell,sec_th)*(C_T(cell,mix_th)-T_SAT)/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_l = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] =0.0;
}
return m_dot_l;
}
DEFINE_SOURCE(enrg_src,cell,mix_th,dS,eqn)
{
real enrg_dot;
Thread *pri_th, *sec_th;
pri_th = THREAD_SUB_THREAD(mix_th,0);
sec_th = THREAD_SUB_THREAD(mix_th,1);
if (C_T(cell,mix_th)>T_SAT)
{
enrg_dot = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT*(C_ T(cell,mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
enrg_dot = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*LAT_HT*(T_ SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*LAT_HT/T_SAT;
}
return enrg_dot;
}
Muhammed_iraq is offline   Reply With Quote

Old   June 17, 2016, 10:43
Default
  #5
New Member
 
SHUJAN
Join Date: Jun 2016
Posts: 17
Rep Power: 10
MDSHUJAN is on a distinguished road
Quote:
Originally Posted by rampal View Post
Hello friends, I have written UDF for phase change in thermosyphon, boiling is happening inside evaporator but there is no condensation inside condenser, I'm confused why this error is happening. I'm writing UDF below, please notify me what is the error in UDF.

#include "udf.h"
#include "sg_mphase.h"
#include "mem.h"
#include "metric.h"
#include "flow.h"
#include "sg.h"
#define T_SAT 373
#define LAT_HT 2455e3
DEFINE_SOURCE(vap_src,cell,pri_th,dS,eqn)
{
real m_dot_v;
Thread *mix_th, *sec_th;
mix_th = THREAD_SUPER_THREAD(pri_th);
sec_th = THREAD_SUB_THREAD(mix_th,1);
/*m_dot_v=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_v = 0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = 0.0;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_v = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
}
return m_dot_v;
}
DEFINE_SOURCE(liq_src,cell,sec_th,dS,eqn)
{
real m_dot_l;
Thread *mix_th, *pri_th;
mix_th = THREAD_SUPER_THREAD(sec_th);
pri_th = THREAD_SUB_THREAD(mix_th,0);
/*m_dot_l=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_l = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_R(cell,sec_th)*(C_T(cell,mix_th)-T_SAT)/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_l = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] =0.0;
}
return m_dot_l;
}
DEFINE_SOURCE(enrg_src,cell,mix_th,dS,eqn)
{
real enrg_dot;
Thread *pri_th, *sec_th;
pri_th = THREAD_SUB_THREAD(mix_th,0);
sec_th = THREAD_SUB_THREAD(mix_th,1);
if (C_T(cell,mix_th)>T_SAT)
{
enrg_dot = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT*(C_ T(cell,mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
enrg_dot = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*LAT_HT*(T_ SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*LAT_HT/T_SAT;
}
return enrg_dot;
}
Hi. Did you get condensation. I am working on similar project, and can't get condensation. Let me know if you get condensation.
MDSHUJAN is offline   Reply With Quote

Old   July 5, 2016, 13:47
Default
  #6
Senior Member
 
Przemek
Join Date: Jun 2011
Posts: 249
Rep Power: 16
gaza is on a distinguished road
Quote:
Originally Posted by rampal View Post
Hello friends, I have written UDF for phase change in thermosyphon, boiling is happening inside evaporator but there is no condensation inside condenser, I'm confused why this error is happening. I'm writing UDF below, please notify me what is the error in UDF.

#include "udf.h"
#include "sg_mphase.h"
#include "mem.h"
#include "metric.h"
#include "flow.h"
#include "sg.h"
#define T_SAT 373
#define LAT_HT 2455e3
DEFINE_SOURCE(vap_src,cell,pri_th,dS,eqn)
{
real m_dot_v;
Thread *mix_th, *sec_th;
mix_th = THREAD_SUPER_THREAD(pri_th);
sec_th = THREAD_SUB_THREAD(mix_th,1);
/*m_dot_v=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_v = 0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = 0.0;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_v = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
}
return m_dot_v;
}
DEFINE_SOURCE(liq_src,cell,sec_th,dS,eqn)
{
real m_dot_l;
Thread *mix_th, *pri_th;
mix_th = THREAD_SUPER_THREAD(sec_th);
pri_th = THREAD_SUB_THREAD(mix_th,0);
/*m_dot_l=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_l = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_R(cell,sec_th)*(C_T(cell,mix_th)-T_SAT)/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_l = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] =0.0;
}
return m_dot_l;
}
DEFINE_SOURCE(enrg_src,cell,mix_th,dS,eqn)
{
real enrg_dot;
Thread *pri_th, *sec_th;
pri_th = THREAD_SUB_THREAD(mix_th,0);
sec_th = THREAD_SUB_THREAD(mix_th,1);
if (C_T(cell,mix_th)>T_SAT)
{
enrg_dot = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT*(C_ T(cell,mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
enrg_dot = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*LAT_HT*(T_ SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*LAT_HT/T_SAT;
}
return enrg_dot;
}
Hi Rampal,
Can you send errors you got?
__________________
best regards
pblasiak
gaza is offline   Reply With Quote

Old   July 14, 2016, 13:02
Default
  #7
Senior Member
 
Przemek
Join Date: Jun 2011
Posts: 249
Rep Power: 16
gaza is on a distinguished road
Quote:
Originally Posted by xiaobingwill View Post
Hello,

I'm modeling phase change flow in a closed thermosyphon. Now my status is having evaporation in my evaporator. But little condensation is found in the cold part. The following pics are my results.

I calculated 200s already, but condensation is still very small.

Any guidance or help will be appreciated.

Thanks,
Xiaobing

Limited condensation happens in the condenser.

Limited condensation happens in the condenser.

Evaporation is good.
Hi Xiaobing,
Did you model this with UDF or built-in Fluent model?
__________________
best regards
pblasiak
gaza is offline   Reply With Quote

Old   July 27, 2016, 12:37
Default
  #8
Senior Member
 
Przemek
Join Date: Jun 2011
Posts: 249
Rep Power: 16
gaza is on a distinguished road
Quote:
Originally Posted by rampal View Post
Hello friends, I have written UDF for phase change in thermosyphon, boiling is happening inside evaporator but there is no condensation inside condenser, I'm confused why this error is happening. I'm writing UDF below, please notify me what is the error in UDF.

#include "udf.h"
#include "sg_mphase.h"
#include "mem.h"
#include "metric.h"
#include "flow.h"
#include "sg.h"
#define T_SAT 373
#define LAT_HT 2455e3
DEFINE_SOURCE(vap_src,cell,pri_th,dS,eqn)
{
real m_dot_v;
Thread *mix_th, *sec_th;
mix_th = THREAD_SUPER_THREAD(pri_th);
sec_th = THREAD_SUB_THREAD(mix_th,1);
/*m_dot_v=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_v = 0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = 0.0;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_v = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
}
return m_dot_v;
}
DEFINE_SOURCE(liq_src,cell,sec_th,dS,eqn)
{
real m_dot_l;
Thread *mix_th, *pri_th;
mix_th = THREAD_SUPER_THREAD(sec_th);
pri_th = THREAD_SUB_THREAD(mix_th,0);
/*m_dot_l=0.0;*/
if (C_T(cell,mix_th)>T_SAT)
{
m_dot_l = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*(C_T(cell, mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_R(cell,sec_th)*(C_T(cell,mix_th)-T_SAT)/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
m_dot_l = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*(T_SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] =0.0;
}
return m_dot_l;
}
DEFINE_SOURCE(enrg_src,cell,mix_th,dS,eqn)
{
real enrg_dot;
Thread *pri_th, *sec_th;
pri_th = THREAD_SUB_THREAD(mix_th,0);
sec_th = THREAD_SUB_THREAD(mix_th,1);
if (C_T(cell,mix_th)>T_SAT)
{
enrg_dot = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT*(C_ T(cell,mix_th)-T_SAT)/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,sec_th)*C_R(cell,sec_th)*LAT_HT/T_SAT;
}
else if (C_T(cell,mix_th)<T_SAT)
{
enrg_dot = 0.1*C_VOF(cell,pri_th)*C_R(cell,pri_th)*LAT_HT*(T_ SAT-C_T(cell,mix_th))/T_SAT;
dS[eqn] = -0.1*C_VOF(cell,pri_th)*C_R(cell, pri_th)*LAT_HT/T_SAT;
}
return enrg_dot;
}
Hi Rampal
Have you solved your problem with no condensation? I have the same problem. Please see here:
http://www.cfd-online.com/Forums/flu...on-doesnt.html
__________________
best regards
pblasiak
gaza is offline   Reply With Quote

Old   October 18, 2016, 14:18
Default
  #9
New Member
 
Join Date: Oct 2016
Location: Ringkobing, Denmark
Posts: 10
Rep Power: 10
Abdelhamid Kassem is on a distinguished road
Anyone succeed to simulate the heat pipe evaporator and condenser?
I'm doing my bachelor project on it and i will appreciate any help in this case because, i'm beginner with fluent however, i know the equations of energy and momentum which need to be written in the udf but i failed to simulate it.
Abdelhamid Kassem is offline   Reply With Quote

Old   December 21, 2016, 12:25
Default Heat Pipe
  #10
New Member
 
Reza
Join Date: Dec 2016
Posts: 2
Rep Power: 0
Rezaa is on a distinguished road
Hi everyone. I am new in the two-phase flow and heat pipe field and I should simulate a wicked heat pipe by OpenFoam. It is appreciated if anyone can help me ... Thanks
Rezaa is offline   Reply With Quote

Reply

« Previous Thread | Next Thread »

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
High values of heat transfer coefficient for laminar flow in pipe Allankey CFX 2 May 28, 2014 13:44
heat transfer along a pipe lysander FLUENT 0 July 28, 2012 00:39
evaporation and condensation aximefu CFX 4 May 14, 2012 00:09
Evaporation and heat pipes Energy FLUENT 6 November 5, 2011 11:50
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 10:11


All times are GMT -4. The time now is 08:39.

Contact Us - CFD Online - Privacy Statement - Top