Conjugate heat transfer

achal · February 8, 2013, 00:40

Problem Description : An iron brick is to be cooled by the use of
water jet, this would include convection from the top surface of brick
and conduction within the brick.
Is that what we call a conjugate heat transfer ?
Can it modelled with out the use of UDF ?
How do I model this, because there is no temperature change observed in the brick?
Any sort of help would highly be appreciated.

Thanks And Regards

Achal

hellorishi · February 12, 2013, 07:08

Hi Achal,

Yes, this would be called CHT problem.
You would need to give a initial temperature to the brick. If there is a water jet cooling the brick, the temperature of iron brick is bound to change. After some "x" seconds it is likely to attain temperature of impending water jet (unless this brick is getting active heat from some other source).

UDF would not be essential.
Which software are you looking at for this kind of modeling?

Cheers
/R

achal · February 16, 2013, 03:40

No, the brick is not getting any heat energy.
I used patch to initialise the temperature the brick.
Using steady state solver , yes, the temperature of brick became that of jet.
Using unsteady state, even if i select 1-2 seconds, it shows the temperature.
Do you think this to correct ?

Another question.

How can I be sure that heat conduction is happening inside the brick ?
I am not able to get a temperature profile of a cross section

I am using Fluent pacakge.

hellorishi · February 16, 2013, 10:17

I am not sure if I understand what you said about about unsteady state and temperature.

What do you see if your take a cross section? It might be good to check if there are volume elements inside the brick. Depending on the meshing technique used, it is possible that there are no volume elements inside the brick.

achal · February 16, 2013, 11:24

I need to know how much time does it take for the brick to reach room temperature, therefore I need unsteady state solver settings. Am i correct ?

I am sure there is volume meshing inside the brick, that is not an issue.

achal · February 16, 2013, 11:26

I also need to get the temperature profile of a surface which is at the centre of brick, how can i do that ?

hellorishi · February 17, 2013, 11:03

ya you are right that unsteady analysis is required to find time to cool the brick. It is kindof tough to guess whats going on without actually looking at the case. I am guessing it post-processing issue...

achal · February 17, 2013, 11:51

have you worked on such a case ?
Also, I would love to share the case file with you; may I have your email address ?

duri · February 18, 2013, 07:26

I think your wall thermal boundary condition is wrong. Use coupled boundary condition at the fluid solid interface wall.

achal · February 18, 2013, 08:34

Hi

I have used coupled boundary condition on the interface.

February 8, 2013, 00:40	Conjugate heat transfer	#1
achal New Member achal Join Date: Feb 2013 Posts: 9 Rep Power: 13	Problem Description : An iron brick is to be cooled by the use of water jet, this would include convection from the top surface of brick and conduction within the brick. Is that what we call a conjugate heat transfer ? Can it modelled with out the use of UDF ? How do I model this, because there is no temperature change observed in the brick? Any sort of help would highly be appreciated. Thanks And Regards Achal

February 18, 2013, 08:34		#10
achal New Member achal Join Date: Feb 2013 Posts: 9 Rep Power: 13	Hi I have used coupled boundary condition on the interface. MARIO276 likes this.

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February 12, 2013, 07:08		#2
hellorishi Senior Member Rishi . Join Date: Mar 2009 Posts: 149 Rep Power: 17	Hi Achal, Yes, this would be called CHT problem. You would need to give a initial temperature to the brick. If there is a water jet cooling the brick, the temperature of iron brick is bound to change. After some "x" seconds it is likely to attain temperature of impending water jet (unless this brick is getting active heat from some other source). UDF would not be essential. Which software are you looking at for this kind of modeling? Cheers /R

February 16, 2013, 03:40		#3
achal New Member achal Join Date: Feb 2013 Posts: 9 Rep Power: 13	No, the brick is not getting any heat energy. I used patch to initialise the temperature the brick. Using steady state solver , yes, the temperature of brick became that of jet. Using unsteady state, even if i select 1-2 seconds, it shows the temperature. Do you think this to correct ? Another question. How can I be sure that heat conduction is happening inside the brick ? I am not able to get a temperature profile of a cross section I am using Fluent pacakge.

February 16, 2013, 10:17		#4
hellorishi Senior Member Rishi . Join Date: Mar 2009 Posts: 149 Rep Power: 17	I am not sure if I understand what you said about about unsteady state and temperature. What do you see if your take a cross section? It might be good to check if there are volume elements inside the brick. Depending on the meshing technique used, it is possible that there are no volume elements inside the brick.

February 16, 2013, 11:24		#5
achal New Member achal Join Date: Feb 2013 Posts: 9 Rep Power: 13	I need to know how much time does it take for the brick to reach room temperature, therefore I need unsteady state solver settings. Am i correct ? I am sure there is volume meshing inside the brick, that is not an issue.

February 16, 2013, 11:26		#6
achal New Member achal Join Date: Feb 2013 Posts: 9 Rep Power: 13	I also need to get the temperature profile of a surface which is at the centre of brick, how can i do that ?

February 17, 2013, 11:03		#7
hellorishi Senior Member Rishi . Join Date: Mar 2009 Posts: 149 Rep Power: 17	ya you are right that unsteady analysis is required to find time to cool the brick. It is kindof tough to guess whats going on without actually looking at the case. I am guessing it post-processing issue...

February 17, 2013, 11:51		#8
achal New Member achal Join Date: Feb 2013 Posts: 9 Rep Power: 13	have you worked on such a case ? Also, I would love to share the case file with you; may I have your email address ?

February 18, 2013, 07:26		#9
duri Senior Member duri Join Date: May 2010 Posts: 245 Rep Power: 16	I think your wall thermal boundary condition is wrong. Use coupled boundary condition at the fluid solid interface wall.