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I'm using different pcms and getting the same result

asked 2018-10-31 14:57:35 -0500

Ulylabcee's avatar

updated 2018-11-01 16:24:32 -0500

I'm using the energyplus 8.9 version. I'm trying to simulate the energy consume with hvac and the thermal confort with natural ventilation. I'm using data sheet for 4 different PCMS and getting the exact same value of consumed energy and room temperatures in all the rooms of the simulated house. In material hysteresis Their latent heat varies from a range of 190KJ/kg to 250kj/kg, so its a pretty big difference. They also have a range of peak temperatures (from 21 to 28). It was expected at least a little change.
I've already tryed to use graus kelvin and celsius, since in the inputoutput reference it is said to use Kelvin but in the program has a C. Already tryed to change the HeatBalanceAlgorithim.

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Have you already looked at example files to see how PCM is modeled in EnergyPlus? The top two to check are:

  • CondFD1ZonePurchAirAutoSizeWithPCM.idf
  • 1ZoneUncontrolledWithHysteresisPCM.idf

Also, to really answer your question you should either add the text of the PCM-related EnergyPlus objects to your post, or add a link to your entire input file in your post so that others can better answer your question.

Aaron Boranian's avatar Aaron Boranian  ( 2018-10-31 15:27:33 -0500 )edit

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answered 2018-11-01 13:52:46 -0500

It is possible that you have such a quantity of PCM mass that it is never completely freezing or melting (in which case total energy storage - 190KJ/kg vs 250kj/kg - would be irrelevant). If I was getting the results you are getting, I would try doing a sensitivity analysis in which I reduce the thickness of the PCM until (hopefully) a difference in performance is observed.

If you haven't already, I would also recommend seeing how a baseline model with no PCM applied performs in comparison to the ones with the PCM. If this also yields the same results, your building is either incredibly massive (thermally speaking) or the PCM object is not being successfully applied.

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Asked: 2018-10-31 14:57:35 -0500

Seen: 204 times

Last updated: Nov 01 '18