# Energy Storage Calculation

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 February 20, 2020, 14:38 Energy Storage Calculation #1 New Member   Join Date: Feb 2020 Posts: 3 Rep Power: 6 Hello, I am running a transient melting and solidfication simulation on PCM. I would like to calculate and record the total energy stored in the PCM with time. In terms of boundary conditions I have a flux on one side of the "box", and convection on the remaining three sides. Anaytically I know it would be a simple energy balance but I don't know how to translate that into Ansys. Any help would be greatly appreciated. Thanks!

 February 20, 2020, 15:56 PCM as Energy Storage #2 Senior Member     Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35 Calculation in a CFD tool is similar to analytical energy balance. Since you are using PCM as an energy storage device, that implies it is able to provide energy as long as it is in liquid phase. Once solidified, it needs to be re-energized or recharged. So, the amount of latent heat available in the remaining liquid is the available energy. In Fluent, you can describe it using a custom-field-function or an expression as the volume Integral of the product of density, liquid fraction, and latent heat of fusion. If using CFF, create a CFF as product of three parameters and then setup a volume integral monitor over whole PCM domain using CFF as variable. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

 February 20, 2020, 16:58 PCM as Energy Storage #3 New Member   Join Date: Feb 2020 Posts: 3 Rep Power: 6 Hi Vinerm, Thanks for that very good suggestion. It makes sense and puts me in the direction. I assume the same procedure would be used to sensible energy but changing latent heat of fusion with Cp and difference in Temperature from initial temperature? Cheers

February 20, 2020, 18:53
Can't plot named expression
#4
New Member

Join Date: Feb 2020
Posts: 3
Rep Power: 6
Hello,
I followed your suggestions and made a named expression as seen in the attached picture. However, when I try to create a plot, it doesn't come up as a report definition. What am I missing here?
Attached Images
 Expression.JPG (25.4 KB, 52 views)

 February 21, 2020, 04:33 Expressions and CFF #5 Senior Member     Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35 Expressions cannot be plotted directly as contours. However, you can select those as monitors during the run. Better option would be to create a CFF and then create a volume integral of the CFF. Yes, you can define the heating and cooling part as well using the sensible heat. In that case, as you mentioned, specific heat is to be used and the reference temperature would either be the temperature of the surroundings or the temperature to which storage system need to supply the energy. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

 Tags pcm, surface average, surface intergral, total energy