topic Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve in CFD Forum

Modeling HEPA Filters in CFDesign using Head Capacity Curve

Anonymous — Tue, 07 Feb 2012 17:49:10 GMT

When trying to replicate the flow through a section of HEPA filter, since I don't know the permiability constant I am using the Head Capacity Curve function. I have pressure drop (in H20) versus Air Velocity (ft/min) and have converted the velocity to flow rate based on the area of the filter section my flow volume is through.

However, the pressure drop that results is approximately double what was input in the Head Capacity Curve. Any ideas as to why this happens?

Thanks

Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve

Royce_adsk — Tue, 07 Feb 2012 17:54:04 GMT

What values did you put into the hea capactiy curve (HCC)? Screenshot might help here.

Did you try adding more mesh?

2D Resistances parts can also provide more accurate results at times.

Are you testing the setup in a smaller model that isn't NDA that you are willing to share?

Thanks,

Royce

Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve

Anonymous — Tue, 07 Feb 2012 18:03:10 GMT

I have attached the setup I used, and the values I loaded for the HCC. I haven't tried to add more mesh yet.

One weird thing did occur, when I initally solved the results were approximately 0.17in H20, and some of the variables in the convergence plot had not seemed to quite level off. When I ran additonal interations the pressure drop jumped from 0.17 in H20 to 0.59 in H20.

Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve

Royce_adsk — Tue, 07 Feb 2012 18:06:44 GMT

The *.cfdst file isn't a very useful file to upload, create a support share file (file menu_save share file) and upload that instead.

See this table for more information on CFD file types:

http://www.cfdesign.com/OnlineHelp/2011/User%20Interface/File/Working%20with%20Files.htm

Thanks!

Royce

Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve

Anonymous — Tue, 07 Feb 2012 19:10:15 GMT

See attached for support share file.

I refined the mesh and re ran, and it had very similar results as mentioned previously.

Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve

Royce_adsk — Tue, 07 Feb 2012 21:20:40 GMT

The poor performance is associated with a character used in the material name that is not supported. Try changing the name of the resistance to "2 inch HEPA Filter Resistance". After I removed the " character the pressure drop was more inline with expectations.

I already tested future builds and warnings are given when this character is used.

-Royce

Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve

Anonymous — Tue, 07 Feb 2012 21:57:01 GMT

Thank you solved my issue.

Can you expect a similar issue when using any punctuation? for just the "?

Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve

Royce_adsk — Tue, 07 Feb 2012 22:56:38 GMT

Here is a warning screen with the list of characters to stay away from.

-Royce

Re: Modeling HEPA Filters in CFDesign using Head Capacity Curve

Anonymous — Fri, 23 Mar 2012 19:27:10 GMT

Is there a standard Head Capacity Curve for HEPA filters? Where can that information be found?