Uncertainty with Energy plus Enthalpy inputs for PCMs

asked 2018-02-05 05:56:08 -0500

Roccan
63 ●1 ●1 ●4

updated 2018-02-05 08:19:57 -0500

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

Hello!

I am doing a PCM simulation in energy plus. To do so, I'm using the object MaterialProperty: PhaseChange. The object itself is very trivial and the input parameters are straightforward, however, the PCM I am trying to simulate has two different histograms. One Enthalpy-Temperature diagram for melting and another for the solidification. To go along, it has different thermal conductivity, density and specific heat values for both solid and liquid states. What is confusing me is that E+ requires only one set of temperature-enthalpy inputs. Which parameters am I supposed to enter, the solidification or melting? Is there a possibility to enter both? For my base-case simulations I have used the melting histogram. As for the thermal conductivity, I believe it is solved with the object MaterialProperty:VariableThermalConductivity, however density and specific heat remain with one input only.

What would be your suggestion to keep the simulation as accurate as possible?

Thank you in advance!

answered 2018-02-11 02:47:11 -0500

Avi
4300 ●2 ●11

You need to use MaterialProperty:PhaseChangeHysteresis instade of MaterialProperty:PhaseChange. Doing that you will be able to set both curves.

You can read in the Engineering Reference and in the Input Output Reference.

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Comments

Thank you, this exactly what I needed. Do I have to update my energy plus, or I can just add the code in the text file and then simulate it?

Roccan ( 2018-02-11 09:18:06 -0500 )edit

@Roccan I might have lost you. Anyway you will need to edit your idf file inorder to change the MaterialProperty either in IDF editor or in a plane text editor. Then run the simulation again.

Avi ( 2018-02-11 10:42:58 -0500 )edit

Sorry, I didn't specify the issue. I don't have this object when I'm in the IDF editor. Maybe I'm using an outdated E+ version? That's why I asked could I just create it in the text editor.

Roccan ( 2018-02-11 13:03:53 -0500 )edit

@Roccan Yes this is out of the latest version 8.8 so you need to install the new version and then run the IDFVersionUpdater which can be found in the PreProcess folder.

Avi ( 2018-02-11 13:10:00 -0500 )edit

Thank you very much!

Roccan ( 2018-02-11 13:40:41 -0500 )edit

In my experiment, I added a phase change material (PCM) to my prototype as layer to the interior wall. In EnergyPlus Software, I define the PCM but I do not know how to add it to the interior wall as layer. Would you please help me in this point?

Talal7757 ( 2018-04-05 02:05:16 -0500 )edit

First you create your PCM as a material object (as you would create any other material), then you need to define the phase change with the MaterialProperty:PhaseChange object (or the phase change hysteresis object as mentioned here). When you've done this, you should have no problems adding a layer of PCM in the construction object. Hope this helps.

Roccan ( 2018-04-11 08:37:11 -0500 )edit

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