Re: [EnergyPlus_Support] Re: Parametric PCM simulations [1 Attachment]

["Jeremiah Crossett jcrossett@xxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

Hi, 

The attached study I did recently on a yacht compares some common PCM's. I use a custom version of E+ with a different PCM model than you are using, so my models would not open for you. 

For a study to determine the PCM properties the method you are using to raise the melt temp with a set freeze point is unrealistic. Instead, when you raise the melt point, you would also want to increase the freeze point so that heat can be rejected from the PCM at night. 

A good starting point is to check node temperatures then set the PCM transition temperatures to fit within the range that the surface either most commonly or under worst case conditions experiences, depending on your design goal..  

Jeremiah D. Crossett | Chief Technological Officer | NRGsim Inc. 

7409 SW Capitol Highway Portland OR, 97219 #204

503-688-8951 | nrgsim.com | Linkedin | Github

On Wed, Jan 4, 2017 at 12:02 PM, Jeremiah Crossett <jcrossett@xxxxxxxxxx> wrote:

Hi, 

Yes the comfort board product should have a limitation of about 10% total savings given the thermal capacity.

Generally a good PCM has a tight transition range, for example from 21C to 24C.. Having a high range means that it would be required for the building to experience the full temperature range in order to use all of the PCM capacity. Most buildings do not get up to 35C. 

Perhaps for your study you might look at a few different PCM's..   Also, I have included some details on the Knaff Comfort Bord.. 

  

Jeremiah D. Crossett | Chief Technological Officer | NRGsim Inc. 

7409 SW Capitol Highway Portland OR, 97219 #204

503-688-8951 | nrgsim.com | Linkedin | Github

On Tue, Jan 3, 2017 at 9:51 PM, poly_purple@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com> wrote:

 

Hi Jeremiah,

Thanks for the reply, I just noticed that I uploaded the wrong file, here's the correct one.

I might have worded that one incorrectly, but what I was trying to achieve in this parametric simulation is to determine the optimum phase change temperature given the weather data, i.e. similar to what the Singapore study did.

The researchers used values from 22-32C[1st image attached] wherein the simulation results [2nd image attached] that the optimum Phase Change Temp is 28C.

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I'm not sure though if I have the parametric simulation set up correctly because the results I get are completely unexpected:

(this is a snippet of the results that I got from the simulation)

IDFNum1 : PhaseChangeTemp: 21.5 | percentageSaving: 1.8037601505497443%

IDFNum2 : PhaseChangeTemp: 22.0 | percentageSaving: 1.8617332591772573%

IDFNum3 : PhaseChangeTemp: 22.5 | percentageSaving: 1.9996598546093505%

IDFNum4 : PhaseChangeTemp: 23.0 | percentageSaving: 2.434157634176394%

IDFNum5 : PhaseChangeTemp: 23.5 | percentageSaving: 7.705738929181642%

IDFNum6 : PhaseChangeTemp: 24.0 | percentageSaving: 6.944291976049036%

IDFNum7 : PhaseChangeTemp: 24.5 | percentageSaving: 6.224276916758244%

IDFNum8 : PhaseChangeTemp: 25.0 | percentageSaving: 5.643097420955074%

IDFNum9 : PhaseChangeTemp: 25.5 | percentageSaving: 5.198121774674616%

IDFNum10 : PhaseChangeTemp: 26.0 | percentageSaving: 4.728777840837902%

IDFNum11 : PhaseChangeTemp: 26.5 | percentageSaving: 3.7395338726936553%

IDFNum12 : PhaseChangeTemp: 27.0 | percentageSaving: 1.87399617839346%

IDFNum13 : PhaseChangeTemp: 27.5 | percentageSaving: 0.05983734301740366%

IDFNum14 : PhaseChangeTemp: 28.0 | percentageSaving: -0.26647783516539975%

IDFNum15 : PhaseChangeTemp: 28.5 | percentageSaving: -0.5274505850699533%

IDFNum16 : PhaseChangeTemp: 29.0 | percentageSaving: 0.03462216485965237%

IDFNum17 : PhaseChangeTemp: 29.5 | percentageSaving: 0.4660878949187268%

IDFNum18 : PhaseChangeTemp: 30.0 | percentageSaving: 0.9192396364598365%

IDFNum19 : PhaseChangeTemp: 30.5 | percentageSaving: 1.577833726593023%

IDFNum20 : PhaseChangeTemp: 31.0 | percentageSaving: 1.7929323542505673%

IDFNum21 : PhaseChangeTemp: 31.5 | percentageSaving: 1.8194452651533959%

IDFNum22 : PhaseChangeTemp: 32.0 | percentageSaving: 1.9278599731923827%

IDFNum23 : PhaseChangeTemp: 32.5 | percentageSaving: 2.20114869557999%

IDFNum24 : PhaseChangeTemp: 33.0 | percentageSaving: 2.3417308228731075%

IDFNum25 : PhaseChangeTemp: 33.5 | percentageSaving: 2.4673593188230933%

IDFNum26 : PhaseChangeTemp: 34.0 | percentageSaving: 2.388213833367072%

IDFNum27 : PhaseChangeTemp: 34.5 | percentageSaving: 2.348160899997142%

IDFNum28 : PhaseChangeTemp: 35.0 | percentageSaving: 2.458831920269978%

------------------

Where the savings in cooling loads was calculated by comparing the cooling loads (ZONE1AIR:Zone Ideal Loads Supply Air Total Cooling Energy [J])of the module with PCMs versus the module without PCMs. 

The graph [2nd image attached] showed that I should have at worst 10% energy savings from cooling loads (PCT @22C or 23C), but the result I got showed that the optimum PCT is at 23.5C and the range where I expect the optimum PCT to be around (28-30) showed extremely low energy savings (even negative for PCT 28 and PCT 28.5), whereas the study had 26% energy savings for PCT28.

I think I made a mistake somewhere but I can't pinpoint exactly where...

Thanks.

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Posted by: Jeremiah Crossett <jcrossett@xxxxxxxxxx>

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D:\Eudora\Attach\73-Meter-PCM-Spec.pdf