Meta-stable States

[henningjp]

Formulas for the meta-stable states just inside the vapor dome are provided in IAPWS R7-97(2012), the "Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam, August 2007". These are not currently included in this IF97 implementation, but could be implemented to provide properties in the meta-stable region.

[henningjp]

Is there any interest in this?

[hlucian]

I would be happy to have this ability. In Refprop, i can enforce metastable conditions using the </>.
I am currently running a in-house developed CFD code for two-phase analysis of steam turbines in
an Euler-Euler formulation. I get good results but since I am using the algebraic expressions of IF-97,
the simulations is really slow. We have started the integration of table lookup in the solver and
it would be nice if I could also add the metastable conditions into the lookup table.

[ibell]

Have you experimented with the tabular backends in CoolProp core? They are not 100% perfect, but are pretty fast if they meet your needs

[hlucian]

No I haven't. I am quite new to Coolprop/Refprop and only have to deal
with it since I would like to update an existing refpropm routine that we
use to compute property tables. The issue is that refpropm does not allow me
to compute metastable conditions for water. Another issue was that Refprop 9
was not consistent when computing the metastable conditions based on T = f(h,p<)
while it worked for h = f(T,p<). As you suggested me in another post, in Refprop 10,
this issue is not present anymore. However, since I had to pay myself for the upgrade
I wanted to give Coolprop a try.

I have now purchased Refprop 10 and started to replace refpropm with the python matlab
wrapper. However, I have a problem now when trying to compute the critical pressure for water.
In Refprop guy and the outdated refpropm I get the value for PCrit = 2.2064MPa. However, using
the python wrapper in Matlab i get 2.237MPa.

I was using the following routine in Matlab

RP = py.ctREFPROP.ctREFPROP.REFPROPFunctionLibrary('C:\Program Files (x86)\REFPROP\REFPRP64.DLL');
MOLSI = RP.GETENUMdll(int8(0),'MASS BASE SI').iEnum;
iMass = int8(0); % 0: molar fractions; 1: mass fractions
iFlag = int8(1); % 0: don't call SATSPLN; 1: call SATSPLN
z = {1.0}; % mole fractions, here a pure fluid, so mole fraction of 1.0
r = RP.REFPROPdll('Water','CRIT','P',MOLSI,iMass,iFlag,0,0,z);
o = double(r.Output);
ZVal = o(1)

Can ou tell me what I am doing wrong? I also tried with different options for iFlag (SATSPLIN)

[hlucian]

I do not know what happend but now it is returning the expected values.
Sorry for the inconvenience, not sure if it was somehow using an older version in
the background.