Issue with the phase envelope on the PH diagram of some refirgerants (e.g., R245fa) for ORC cycle

[nicolas-rangel]

Hello.
I am trying to plot a simplified (enthalpy vs pressure) thermodynamic cycle using refrigerant R245fa, for an ORC calculation.
The issue is that when I use CoolProp's PropertyPlot() as a background template, the phase envelope does not coincide with the actual state of my fluid. For instance, when calling upon the CoolPropsSI module, the library correctly predicts the state of the fluid to be a liquid, for example, however when plotted on top of CoolProp's property plot, the same PH values end up being plotted on the two-phase fluid region (ie, within the phase envelope).

The first picture below shows my current cycle using only CoolProp (along with the PH values being plotted). The second plot shows the same values I obtain from CoolProp being plotted on top of a published phase diagram for the same refrigerant I found online (https://www.researchgate.net/profile/Claudia-Toro/publication/260791538/figure/fig3/AS:340292772352008@1458143528020/R245fa-Pressure-Enthalpy-diagram.png) This second plot accurately predicts the fluid's states.

I imagine this has to do with the reference state of the fluid being assumed by CoolProp, however, I don't see any way to modify these initial conditions in the PropertyPlot() module. Thanks in advance for any help or tip anyone can provide.

[jowr]

You can set the state per fluid, please have a look here: http://www.coolprop.org/coolprop/HighLevelAPI.html#reference-states

Do not expect too much from the plotting code, it is partly broken.

[nicolas-rangel]

Thank you Jowr. I tried all the built-in reference states, but still none did the trick.
Do you know by chance another library that might be better for Ts, PH plotting?

[frank998]

Hey @nicolas-rangel
I built a app in MATLAB for plotting P-h/T-s/T-h chart for myself, for which the refrigerant property is calculated by CoolProp. I try to duplicate your example in my app. The result seems normal, as the second plot you provide. See the pic I paste below. For your information, when plotting the P-h chart, I plot the saturated line by myself by calculate properties at quality Q=0 and Q=1. So may be the problem is from the PropertyPlot()? I do not check for that.

I also plot a version using REFPROP, which gives the same results.

[fwitte]

You could give it a try with https://github.com/fwitte/fluprodia. It uses CoolProp to generate the diagrams.