Helmholtz free energy using MATLAB

[gabriel...@lepten.ufsc.br]

    Hi, I am currently using CoolProp in MATLAB to calculate helmholtz free energy, but I can't use the form G = alpha0 + alphar, because I get the following error:

>> CoolProp.PropsSI('alphar','T',t, 'P', p, 'Water')

Warning: This input [48: "alphar"] is not valid for keyed_output 

Error using CoolPropMATLAB_wrap

Fatal error.

Error in CoolProp.PropsSI (line 2)

  [varargout{1:max(1,nargout)}] = CoolPropMATLAB_wrap(313,varargin{:});

So I am calculating G = U - T*S, where S = S(T,P) and U = U(T,P) are calculated using CoolProp. For the derivatives of Helmholtz energy I just use the chain rule and CoolProp to calculate the U and S derivatives.

Is there something I can do to use the alpha0+alphar form?

Can I calculate the way I did?

[Ian Bell]

What version of CoolProp are you using?  I thought I had fixed this issue in v6.  Also we could export Helmholtz energy directly , so you would not need to do ideal plus residual sum.

--
You received this message because you are subscribed to the Google Groups "coolprop-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to coolprop-user...@googlegroups.com.
To post to this group, send email to coolpro...@googlegroups.com.
Visit this group at https://groups.google.com/group/coolprop-users.
For more options, visit https://groups.google.com/d/optout.

[Ian Bell]

I added more access to Helmholtz energy here: https://github.com/CoolProp/CoolProp/issues/1086

alphar was definitely working in v6.  Again, what version of CoolProp are you using?

Best,

Ian

On Thursday, May 26, 2016 at 6:55:50 AM UTC-6, Ian Bell wrote:

What version of CoolProp are you using?  I thought I had fixed this issue in v6.  Also we could export Helmholtz energy directly , so you would not need to do ideal plus residual sum.

On May 25, 2016 7:19 PM, <gabriel...@lepten.ufsc.br> wrote:

    Hi, I am currently using CoolProp in MATLAB to calculate helmholtz free energy, but I can't use the form G = alpha0 + alphar, because I get the following error:

>> CoolProp.PropsSI('alphar','T',t, 'P', p, 'Water')

Warning: This input [48: "alphar"] is not valid for keyed_output 

Error using CoolPropMATLAB_wrap

Fatal error.

Error in CoolProp.PropsSI (line 2)

  [varargout{1:max(1,nargout)}] = CoolPropMATLAB_wrap(313,varargin{:});

So I am calculating G = U - T*S, where S = S(T,P) and U = U(T,P) are calculated using CoolProp. For the derivatives of Helmholtz energy I just use the chain rule and CoolProp to calculate the U and S derivatives.

Is there something I can do to use the alpha0+alphar form?

Can I calculate the way I did?

--
You received this message because you are subscribed to the Google Groups "coolprop-users" group.

To unsubscribe from this group and stop receiving emails from it, send an email to coolprop-users+unsubscribe@googlegroups.com.
To post to this group, send email to coolprop-users@googlegroups.com.