[esp-r] Re: Phase change materials properties

[rida at rhrk.uni-kl.de]

Hi Juanita,

 

There is a unit typo in the interface where thermal conductivity should be in [W/m^2K].

 

Using the interface you can only generate the file accounts for the linear function of latent heat of PCM. Also ESP-r can handle other function to calculate the latent heat capacity including exponential but for that you need to edit the *spf file manually and change for a different type.

 

For the linear case: a and b represent the coefficient for the latent heat only. y: the Latent heat x: Temperature.

If you know the characteristic at the onset and offset you can get a and b. you have two coordinate of a linear equation (0,Tm) (Maximum latent,TS). 

The apparent heat capacity= Cpsolid + Latent(T)

When T is less than Tm or greater then Ts latent is zero.

 

Check that your *spf file is linked to the model! Open your ‘model’.cfg file and look for a line with: *spf (your special material file name) 

If you couldn’t find it I think you have to add it manually and save.

 

Hope that help!

 

Regards,

Mohamad Rida

 

 

From: esp-r-bounces at lists.strath.ac.uk <esp-r-bounces at lists.strath.ac.uk> On Behalf Of Juanita Solano Guzmán
Sent: 29 July 2019 09:49
To: esp-r at lists.strath.ac.uk
Subject: [esp-r] Phase change materials properties

 

Hello to All, 

 

I am currently trying to figure out the meaning of the input values and units when defining a phase-change material. 

 

- Melting temperature degC: no questions
- Solidification temperature degC: no questions 
- Thermal conductivity in the solid phase J/kg: In the ESPr interface the thermal conductivity is shown to have units of J/kg, I assume this is a mistake? 
- Thermal conductivity in the liquid phase J/kg: same as above
- Specific heat  J/kg.K: no questions
- Latent heat of member a J/kg.K^2 and b J/kg.K: In a previous post I read that a and b, represent the values of a linear function y = ax + b. Woud this linear function correspond to the effective heat capacity given by:

 

C_eff = L/(Te-To) + Cp(T=To)

 

L - latent heat 

Te - Offset temperature

To - Onset temperature 

Cp - specific heat at the onset temperature 

 

in that case, would "a" be equal to L/(Te-To) and "b" to Cp(T=To)?  And then "x" in the linear function corresponds to the temperature? 

 

Thank you in advance for your help, 

 

Best Regards,

Juanita 

 

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