CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   heat pipe simulation in Fluent (http://www.cfd-online.com/Forums/fluent/83468-heat-pipe-simulation-fluent.html)

nahmed December 30, 2010 04:54

heat pipe simulation in Fluent
 
Hi,

I am using Fluent to perform heat pipe simulations. I am trying to solve it by VOF multiphase model but i am finding it hard to incorporate the boiling and condensation mechanisms at the liquid and vapor interface, both at condensor and evaporator side.

I was wondering if any one of you have tried to tackle the same sort of problem or could probably suggest me what could be a reasonable way to interact the two phases?

Moreover do i need to use some UDFs for boiling and condensation? What kind of operating conditions are more suitable? steady or unsteady?

Thanks.

nahmed January 1, 2011 08:27

Anyone with good suggestions on my problem?

nahmed January 9, 2011 15:39

gentle bounce!

hilmi January 13, 2011 02:59

hello there
 
i am an undergraduate student, and i was also assigned to develop a CFD analysis of a heat pipe. im really really new with fluent. is FLUENT really can do modeling, meshing, and analysis of a heat pipe?

how to model for the wick structure?

airleacheri January 13, 2011 03:11

cheaptheatreticket
 
I was also assign to build up a CFD examination of a temperature pipe. i am an apprentice undergraduate student , . I am actually new with confident. is FLUENT in truth can do model, mesh, and analysis of a heat pipe?

barzin January 31, 2011 18:53

Hi guys,,,I'm dead new to Fluent and I need to model a heat pipe using Nano fluids as working fluid,please let me know if u find any idea how to it and I'll do the same,,,,cheers

JohannVV February 4, 2011 04:54

Hi all, I'm also working with phase change and use fluent to solve my problems.
I started with the film boiling tutorial from fluent and I have some questions concerning the code and the function of it.(it is not a programming issue)
The question is, where is the information that the evaporation should start at a particular temperature? For example at 100°C with water!
Here the code concerning my problem.


DEFINE_ADJUST(area_density, domain)
{
Thread *t;
Thread **pt;
cell_t c;
Domain *pDomain = DOMAIN_SUB_DOMAIN(domain,P_PHASE);
real voidx, voidy, voidz=0;

...
...
mp_thread_loop_c (t,domain,pt)
if (FLUID_THREAD_P(t))
{
Thread *tp = pt[P_PHASE];

begin_c_loop (c,t)
{

#if RP_3D
C_UDMI(c,t,0) = (C_VOF_G(c,tp)[0]*C_T_G(c,t)[0]+C_VOF_G(c,tp)[1]*C_T_G(c,t)[1]+C_VOF_G(c,tp)[2]*C_T_G(c,t)[2]);
#endif

#if RP_2D
C_UDMI(c,t,0) = (C_VOF_G(c,tp)[0]*C_T_G(c,t)[0]+C_VOF_G(c,tp)[1]*C_T_G(c,t)[1]);
#endif

}
end_c_loop (c,t)
}
...
...
}

DEFINE_SOURCE(gas, cell, thread, dS, eqn)
{

real x[ND_ND];
real source;
Thread *tm = THREAD_SUPER_THREAD(thread);
Thread **pt = THREAD_SUB_THREADS(tm);

real Kl = C_K_L(cell, pt[1])*C_VOF(cell, pt[1]), Kg = C_K_L(cell, pt[0])*C_VOF(cell, pt[0]);
real L = 1e5;

source = (Kl+Kg)*C_UDMI(cell,tm,0) / L;



C_UDMI(cell, tm, 1) = source;


C_UDMI(cell, tm, 2) = -source*L;



dS[eqn] =0;

return source;
}

DEFINE_SOURCE(liquid, cell, thread, dS, eqn)
{
real x[ND_ND];
real source;
Thread *tm = THREAD_SUPER_THREAD(thread);
Thread **pt = THREAD_SUB_THREADS(tm);

source = -C_UDMI(cell, tm, 1);

dS[eqn] = 0;

return source;
}

DEFINE_SOURCE(energy, cell, thread, dS, eqn)
{
real x[ND_ND];
real source;
Thread *tm = thread;



source = C_UDMI(cell, tm, 2);
dS[eqn] = 0;

return source;
}

nahmed February 5, 2011 09:19

@JahanVV
It is not clear if the phase change you want to do is in closed domain like what happens in case of a heat pipe. as for my application I have just started to look into the UDF manual of Fleunt and at this stage, I am trying to write a UDF for heat source in evaporator and heat sink in condensor section of the heat pipe. If any one can guide me in writing the code that would be highly appreciated.

@Others
I am not completely sure but the simulation of heat pipe is possible in Fluent. It depends upto what extent you want to be precise about your simulation. So far I have not come up with a succesful startegy to model phase change inside a heat pipe. I guess we can do without it as well by modelling wick and the vapor region separately.

JohannVV February 6, 2011 15:28

Hi nahmed,
with the phase change Ii want to model an evaporator an a condenser in a heat pump. For my understanding is my problem with the heat pump similar to yours with the heat pipe.

I do not see a problem to set up a case in fluent, including the programming stuff. I have a problem with the mechanism of evaporation and condensation. I'm desperately searching for some equitation’s to establish the model from the mathematical/physical side.

So if you could help me with the theory (equitation’s, treatments), I could help you with the case setup including writing of the udf!

haghshenasfard June 30, 2011 06:35

Quote:

Originally Posted by barzin (Post 293020)
Hi guys,,,I'm dead new to Fluent and I need to model a heat pipe using Nano fluids as working fluid,please let me know if u find any idea how to it and I'll do the same,,,,cheers

hello
could you please send me any information about CFD simulation of heat pipes? I need a udf for simulations, I you need I can send you a new paper in this field,
masoud734@yahoo.com

sharonbashyam October 12, 2012 05:49

UDF for evaporating and condensation in heat pipe
 
please any one kindly mail me the udf regarding the evaporation and condensation process in heat pipe ..if u would do kindly i would be obliged....my email id is sharon340mech@yahoo.com

mecman July 23, 2013 19:19

Hi all
i want simulate heat pipe in fluent,but i dont Know haw simulate boilnig with Vof model in heat pipe...please any one kindly mail me the udf regarding the evaporation and condensation process in heat pipe ..if u would do kindly i would be obliged....my email id is m.bahreini1990@gmail.com


All times are GMT -4. The time now is 19:04.