Excel Mixtures

[Miles Abarr]

My first quick question is if there is a thorough documentation of Excel CoolProp syntax? I managed to discover how to do mixtures indirectly from another user's question, but I imagine there are still things I don't know how to do.

My main question has to do with an error I am getting with this particular mixture: "HEOS::Methane[0.042]&Ethane[0.845]&nButane[0.028]&Pentane[0.085]"

When I am not in the phase change region, the CoolProp outputs seem to match REFPROP pretty well, for example in Excel I get PropsSI("H","P",100000, "T",300,  "HEOS::Methane[0.042]&Ethane[0.845]&nButane[0.028]&Pentane[0.085]")/1000 = 614.90 kJ/kg. Putting the same mixture and state into REFPROP gives 614.69 kJ/kg. However, when I get to the phase change region of 159.5K to 253.54K at 0.1MPa (determined in REFPROP), Excel CoolProp is not able to calculate states in that region. Any advice? Is there a way to change the fluid state model or something that might help?

Miles

[Ian Bell]

Miles,

For the high-level interface, read this page in its entirety : http://www.coolprop.org/dev/coolprop/HighLevelAPI.html

Ask questions for things that are unclear.  We can fix the docs to make things clearer.

Intentionally, the interface for mixtures is limited in Excel to use through PropsSI.  If you want to have access to the lower-level capabilities of mixtures, you need to use an environment that supports a more object-oriented style.  See for instance http://www.coolprop.org/dev/coolprop/LowLevelAPI.html .  Perhaps also http://www.coolprop.org/dev/coolprop/LowLevelAPI.html#access-from-high-level-interface .

For two-phase inputs with PT as inputs, I believe the algorithms in CoolProp are not configured to be able to do those types of calculations, only saturation calculations.  It's a limitation that could be overcome, but the required algorithms are complex and I simply don't have the energy for it.  It's very complicated.  REFPROP support for mixture flash calculations is much better.

Ian

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