binary pair CO2&N2 gives wrong density and fails on saturation pressure caluculation

[ox-en-frog]

Good evening,

CoolProp fails to calculate the saturation pressure of a binary mixture and exits with an error message.

Steps to Reproduce

1. set binary pair CO2&N2 at 0.95,0.05
2. try to update to saturation state (Q=0), fails for all temperatures I tested.

throws: ValueError Traceback (most recent call last) in ----> 1 HEOS.update(CP.QT_INPUTS, 0,290.)

CoolProp/AbstractState.pyx in CoolProp.CoolProp.AbstractState.update()

CoolProp/AbstractState.pyx in CoolProp.CoolProp.AbstractState.update()

ValueError: solver_rho_Tp was unable to find a solution for T= 290, p=7.05883e+06, with guess value 13230 with error: The molar density of -4230.149318 mol/m3 is below the minimum of 0.000000 mol/m3

Expected behavior: [What you expect to happen] return the saturation pressure of roughly 75 bar.

Actual behavior: [What actually happens] CooolProp calculates negative density and fails, throws an error message

Versions

In [16]: import CoolProp In [17]: print(CoolProp.version) 6.4.2dev

downloaded and compiled September 14th, 2022

Access via python (ipython interface, python 3.10) on Debian Linux .

Additional Information

if you change Q to a value near 0, it works:

In [18]: HEOS.update(CP.QT_INPUTS, 0.001,290.)

In [19]: HEOS.p() Out[19]: 7484127.52168147

If possible, please post examples and/or screenshots of the issue.

import CoolProp.CoolProp as CP

HEOS = CP.AbstractState("HEOS", "CO2&N2")

HEOS.set_mole_fractions([0.95,0.05])

HEOS.update(CP.QT_INPUTS, 0,290.)

Thanks for the great work!