Bug in flash routines with fixed phase

[jowr]

Calling FlashRoutines::PHSU_D_flash with a pre-specified phase flag does not populate the state object properly. There is something wrong with the if-clause, it seems to be misplaced, see https://github.com/CoolProp/CoolProp/blob/master/src/Backends/Helmholtz/FlashRoutines.cpp#L727-L733 .

import CoolProp
state = CoolProp.AbstractState('HEOS','R134a')
state.update(CoolProp.HmassP_INPUTS, 394738, 101325)
state.T()
CoolProp.CoolProp.PropsSI("T","H",394738,"P",101325,"R134a")
state.specify_phase(CoolProp.iphase_gas)
state.update(CoolProp.HmassP_INPUTS, 394738, 101325)
state.specify_phase(CoolProp.iphase_unknown)
state.update(CoolProp.HmassP_INPUTS, 394738, 101325)
state.specify_phase(CoolProp.iphase_not_imposed)
state.update(CoolProp.HmassP_INPUTS, 394738, 101325)

[jowr]

This one affects a couple of flash routines...

import CoolProp
state = CoolProp.AbstractState('HEOS','R134a')
state.update(CoolProp.HmassP_INPUTS, 394738, 101325)
T = state.T()
p = state.p()
h = state.hmass()
s = state.smass()
d = state.rhomass()
state.specify_phase(CoolProp.iphase_gas)
state.update(CoolProp.HmassP_INPUTS, h, p)
state.update(CoolProp.PSmass_INPUTS, p, s)
state.update(CoolProp.DmassP_INPUTS, d, p)
state.specify_phase(CoolProp.iphase_not_imposed)
state.update(CoolProp.HmassP_INPUTS, h, p)
state.update(CoolProp.PSmass_INPUTS, p, s)
state.update(CoolProp.DmassP_INPUTS, d, p)

[ibell]

What is wrong? Can you explain? I should be able to fix it if you can clarify.

[jowr]

Have you tried running the code above? Does it work for you?

Here is what I experienced:
In some of the flash routines, the if-clause if (HEOS.imposed_phase_index != iphase_not_imposed) seems to turn off all calculations and not only the phase determination. The state object does not get populated and the code fails because the internal temperature HEOS._T is not a number.

In short: I think the if-clauses have to be restructured to respect an imposed phase. If the phase is not imposed, everyhting is finde because the phase detection fills the variables required during the post update steps. I am not sure which flash routines are affected, but I found at least three (see above).

It should be fixable, but I do not feel comfortable making some sort of a hotfix because there still a few things in the HEOS backends that I do not understand completely.

[ibell]

Hmm, this does seem like a bug. Let me see what I can do.

On Fri, May 15, 2015 at 2:21 AM, Jorrit Wronski notifications@github.com
wrote:

Have you tried running the code above? Does it work for you?

Here is what I experienced:
In some of the flash routines, the if-clause if (HEOS.imposed_phase_index
!= iphase_not_imposed) seems to turn off all calculations and not only
the phase determination. The state object does not get populated and the
code fails because the internal temperature HEOS._T is not a number.

In short: I think the if-clauses have to be restructured to respect an
imposed phase. If the phase is not imposed, everyhting is finde because the
phase detection fills the variables required during the post update steps.
I am not sure which flash routines are affected, but I found at least three
(see above).

It should be fixable, but I do not feel comfortable making some sort of a
hotfix because there still a few things in the HEOS backends that I do not
understand completely.

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