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-   -   Solid-Solid CHT Model (http://www.cfd-online.com/Forums/cfx/24382-solid-solid-cht-model.html)

Parthipan August 8, 2007 09:22

Solid-Solid CHT Model
 
Dear all,

I am modelling a solid-solid CHT model in CFX. It consist of an inner volume and an outer bounding volume. The inner volume is the source of heat and I want to see the heat transfer in the outer volume. I have been given only the Thermal conductivity of both the materials and the heat produced in 'Watts' from the inner volume.

Which is right?

Case1: Modelling both the inner volume and outer volume and specifying the inner volume as source.

or

Case2: Modelling only the outer volume and specifying the inner surfaces as Wall with heat transfer coefficient.

If it is Case1, then how could I give the source. Do I have to just divide the value in Watts by the volume of the inner volume and enter the source value in kg/m^3?

If it is Case2, then is there a possiblity to calculate the heat transfer coefficient using Thermal conductivity?

Waiting for your replies.......

Thank you.

opaque August 8, 2007 11:04

Re: Solid-Solid CHT Model
 
Dear Parthipan,

Case 1: Create the a subdomain for the inner volume, and add an "Energy" source. Option = Total Source and you enter your value in Watts.

Case 2: I do not see why you need a heat transfer coefficient. First you must determined the heat flux across the interface between the inner and outer volumes. That should be imposed as a Option = Heat Flux in boundary condition. Using a heat transfer coefficient implies that the source (heat flux) is dependent of the temperature in the outer volume, is it?

Hope this helps.

Opaque


Trang August 9, 2007 03:49

Re: Solid-Solid CHT Model
 
Hi Opaque,

I am doing the similar simulation. However, I expected that on the surface of one solid, there is a reaction. Then I want to put heat flux on the interface between them. Do you know how to calculate this heat flux, I had only activation energy and the thickness of the layer at the interface. And if we have the energy, can we dive it to surface area to get the flux?.

Thank you in advance.

Parthipan August 16, 2007 04:40

Re: Solid-Solid CHT Model
 
Thank you Opaque.

I have decided to take the case 1. I understand that the interfaces boundary conditions are automatically assigned to the interfaces between the volumes. How should I / Should I apply the heat flux across the interface between the inner and outer volumes in CFX?

opaque August 16, 2007 14:32

Re: Solid-Solid CHT Model
 
Dear Parthipan,

If you are specifying the volumetric source for the inner volume, you are done. There is nothing else to do..

Opaque..


Parthipan August 17, 2007 05:10

Re: Solid-Solid CHT Model
 
Thank you again Opaque. I will get back when I am finished with the solving.

Parthipan August 21, 2007 08:58

Re: Solid-Solid CHT Model
 
After Performing a steady state calculation, I find that the temperature is very high than expected.

I did the calculation with the following settings.

Output control -> Solid Timescale Control -> Physical Timescale -> 5 s

I tried the calculation agian with

Output control -> Solid Timescale Control -> Physical Timescale -> 0.1 s

Now the Temperature is somewhat nearer to my expectation.

How could I come to a conclusion with my Physical Timescale for the solid?

Thank you.

suribabu September 4, 2007 05:29

solid and gas phase
 
hellow friend.

here i have one dout in ansys cfx. iam doing scrubber analysis which is used for removeing sulfur content in flue gas. i have a one reaction i want to do chemical reaction between them.

caco3(s)+so2(g).............. caso3(s)+co2(l).

how to do these any one can help me


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