Re: [EnergyPlus_Support] PHASE CHANGE MATERIAL MODELLING- URGENT

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

- Should I input the temperature and enthalpy data directly from DSC curves?

• Yes most likely, but it depends on how the DSC curve data has been processed.

- Or should I follow this equation for calculating the enthalpy at each step? (below)

Considering a CONSTANT SPECIFIC HEAT from product data sheets (for example 2000)- (And constant thermal conductivity):

• Yes on constant specific heat and conductivity  
  

Energy Plus equation for PCMs:  Cp = h2-h1 / T2-T1

• This is also correct if it is the case that your DSC is not already averaged.

So considering an enthalpy of 0 at -20:

h2 = h1 + (T2-T1)*Cp

h2 = 0 + (10-(-20)) * 2000

is this correct or should I just input the data from DSC curves? There are so many confusing explanations in previous studies I have found, I am really in doubt as what I have to do, if somebody could help, it would be really really great!!

• Please send the DSC, perhaps after having a look then better advice can be given. 

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

7409 SW Capitol Highway Portland OR, 97219 #204

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

On Thu, Mar 9, 2017 at 7:11 AM, shahrzadmars@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

I have been trying to understand how to model PCMs in Energy Plus and have been reading papers about it, but I'm still not sure how to input the data into the material properties section for PCMs. My questions are:

- Should I input the temperature and enthalpy data directly from DSC curves?

- Or should I follow this equation for calculating the enthalpy at each step? (below)

Considering a CONSTANT SPECIFIC HEAT from product data sheets (for example 2000)- (And constant thermal conductivity):

Energy Plus equation for PCMs:  Cp = h2-h1 / T2-T1

So considering an enthalpy of 0 at -20:

h2 = h1 + (T2-T1)*Cp

h2 = 0 + (10-(-20)) * 2000

is this correct or should I just input the data from DSC curves? There are so many confusing explanations in previous studies I have found, I am really in doubt as what I have to do, if somebody could help, it would be really really great!!

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Posted by: Jeremiah Crossett <jcrossett@xxxxxxxxxx>

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