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Fixes two-phase states for PHSU_D_flash

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Closes https://github.com/CoolProp/CoolProp/issues/289

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
This commit is contained in:
Ian Bell
2014-12-06 14:27:02 -05:00
parent a11dcfb67c
commit 1fc5e43a34
2 changed files with 64 additions and 2 deletions
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61
src/Backends/Helmholtz/FlashRoutines.cpp
View File

@@ -629,6 +629,41 @@ void FlashRoutines::PT_Q_flash_mixtures(HelmholtzEOSMixtureBackend &HEOS, parame
NR.call(HEOS, IO);
}
}
void FlashRoutines::HSU_D_flash_twophase(HelmholtzEOSMixtureBackend &HEOS, long double rhomolar_spec, parameters other, long double value)
{
class Residual : public FuncWrapper1D
{
public:
HelmholtzEOSMixtureBackend &HEOS;
long double rhomolar_spec, Qd, Qo;
parameters other;
long double value;
Residual(HelmholtzEOSMixtureBackend &HEOS, long double rhomolar_spec, parameters other, long double value) : HEOS(HEOS), rhomolar_spec(rhomolar_spec), other(other), value(value){};
double call(double T){
HEOS.update(QT_INPUTS, 0, T);
HelmholtzEOSMixtureBackend &SatL = HEOS.get_SatL(),
&SatV = HEOS.get_SatV();
// Quality from density
Qd = (1/HEOS._rhomolar-1/SatL.rhomolar())/(1/SatV.rhomolar()-1/SatL.rhomolar());
// Quality from other parameter (H,S,U)
Qo = (value-SatL.keyed_output(other))/(SatV.keyed_output(other)-SatL.keyed_output(other));
// Residual is the difference between the two
return Qo-Qd;
}
} resid(HEOS, rhomolar_spec, other, value);
std::string errstr;
// Critical point for pure fluids, slightly different for pseudo-pure, very different for mixtures
long double Tmax_sat = HEOS.calc_Tmax_sat() - 1e-13;
// Check what the minimum limits for the equation of state are
long double Tmin_satL, Tmin_satV, Tmin_sat;
HEOS.calc_Tmin_sat(Tmin_satL, Tmin_satV);
Tmin_sat = std::max(Tmin_satL, Tmin_satV) - 1e-13;
Brent(resid, Tmin_sat, Tmax_sat-0.01, DBL_EPSILON, 1e-12, 20, errstr);
}
// D given and one of P,H,S,U
void FlashRoutines::PHSU_D_flash(HelmholtzEOSMixtureBackend &HEOS, parameters other)
{
@@ -735,9 +770,31 @@ void FlashRoutines::PHSU_D_flash(HelmholtzEOSMixtureBackend &HEOS, parameters ot
}
else
{
throw NotImplementedError("Two-phase for PHSU_D_flash not supported yet");
}
// Now we know that temperature is between Tsat(D) +- tolerance and the minimum temperature for the fluid
if (other == iP){
// Iterate to find T(p), its just a saturation call
// Set some input options
SaturationSolvers::saturation_PHSU_pure_options options;
// Specified variable is pressure
options.specified_variable = SaturationSolvers::saturation_PHSU_pure_options::IMPOSED_PL;
// Use logarithm of delta as independent variables
options.use_logdelta = false;
// Actually call the solver
SaturationSolvers::saturation_PHSU_pure(HEOS, HEOS._p, options);
// Load the outputs
HEOS._phase = iphase_twophase;
HEOS._Q = (1/HEOS._rhomolar-1/HEOS.SatL->rhomolar())/(1/HEOS.SatV->rhomolar()-1/HEOS.SatL->rhomolar());
HEOS._T = HEOS.SatL->T();
}
else{
// Residual is difference in quality calculated from density and quality calculated from the other parameter
// Iterate to find T
HSU_D_flash_twophase(HEOS, HEOS._rhomolar, other, value);
}
}
}
// Check if vapor/solid region below triple point vapor density
else if (HEOS._rhomolar < component->triple_vapor.rhomolar)

5
src/Backends/Helmholtz/FlashRoutines.h
View File

@@ -84,6 +84,11 @@ public:
/// @param Tmax The higher temperature limit [K]
static void HSU_P_flash_singlephase_Brent(HelmholtzEOSMixtureBackend &HEOS, parameters other, long double value, long double Tmin, long double Tmax);
/// A generic flash routine for the pairs (D,H), (D,S), and (D,U) for twophase state. Similar analysis is needed
/// @param HEOS The HelmholtzEOSMixtureBackend to be used
/// @param other The index for the other input from CoolProp::parameters; allowed values are iP, iHmolar, iSmolar, iUmolar
static void HSU_D_flash_twophase(HelmholtzEOSMixtureBackend &HEOS, long double rhomolar_spec, parameters other, long double value);
/// A generic flash routine for the pairs (D,P), (D,H), (D,S), and (D,U). Similar analysis is needed
/// @param HEOS The HelmholtzEOSMixtureBackend to be used
/// @param other The index for the other input from CoolProp::parameters; allowed values are iP, iHmolar, iSmolar, iUmolar