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Buuilding a model to describe the uptake of hydrogen in sodium alanate.

Posted Jun 28, 2012, 6:41 p.m. EDT Chemical Reaction Engineering Version 4.3 3 Replies

Kevin Smith
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I am trying to model a material using a simple geometry (donut with cooling on the exterior and hydrogen delivered at the interior). This model will couple conservation of mass, momentum, energy and chemical kinetics in one shot. But the form of the equations don't seem to mesh with the selectable physics in the menu. Attached is a document that addresses the physics used in COMSOL previously as I am trying to verify results, but I am struggling to put the equations into the program. The relevant pages in the pdf file are 24-35 under model description. Does this mean I need to use the pde option using the common form and just add in the equations? Specific equations that need to be added are 4.4.1-1, 4.4.1-3, 4.4.3-1, 4.4.5-3a, 4.4.5-3b, 4.4.5-5 and table 4.4.5-1.

Afterwards are 4 pages of inputs presented for use in the program and shown in one text (.txt) file annotated for clarity and brevity.

The two biggest questions besides the best way to add in the equations are:

How do I put in a cubic spline fit for the data in table 4.4.5-1?

How do I handle the pressure terms in 4.4.3-1, namely adding their physics into the program?
3 Replies Last Post Aug 2, 2012, 8:38 a.m. EDT
Kevin Smith
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Posted: 1 decade ago Jun 29, 2012, 5:43 p.m. EDT
Attached is my model as it stands, I used piecewise functions to describe the reaction kinetics, but the physics models don't seem to like my choice of non-dimensional concentration and temperature in the model.
Attached is my model as it stands, I used piecewise functions to describe the reaction kinetics, but the physics models don't seem to like my choice of non-dimensional concentration and temperature in the model.

Attachments:

Jhuang Yu-Siang
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Posted: 1 decade ago Jul 4, 2012, 2:42 p.m. EDT
I can't open your COMSOL files correctly.
I can't open your COMSOL files correctly.
Claudio Zagano
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Posted: 1 decade ago Aug 2, 2012, 8:38 a.m. EDT

Attached is my model as it stands, I used piecewise functions to describe the reaction kinetics, but the physics models don't seem to like my choice of non-dimensional concentration and temperature in the model.


I tried to run your model "hydride.mph" but it goes in error: "There are cyclic dependencies - variable name: epsilon error in multiphysics compilation - error in automatic sequence generation"
Did you still further develop the model?

Thanks
[QUOTE] Attached is my model as it stands, I used piecewise functions to describe the reaction kinetics, but the physics models don't seem to like my choice of non-dimensional concentration and temperature in the model. [/QUOTE] I tried to run your model "hydride.mph" but it goes in error: "There are cyclic dependencies - variable name: epsilon error in multiphysics compilation - error in automatic sequence generation" Did you still further develop the model? Thanks

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