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cantera/src/thermo/MixtureFugacityTP.cpp

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/**
* @file MixtureFugacityTP.cpp
* Methods file for a derived class of ThermoPhase that handles
* non-ideal mixtures based on the fugacity models (see \ref thermoprops and
* class \link Cantera::MixtureFugacityTP MixtureFugacityTP\endlink).
*/
/*
* Copyright (2005) Sandia Corporation. Under the terms of
* Contract DE-AC04-94AL85000 with Sandia Corporation, the
* U.S. Government retains certain rights in this software.
*/
#include "cantera/thermo/MixtureFugacityTP.h"
#include "cantera/thermo/VPSSMgr.h"
#include "cantera/thermo/PDSS.h"
#include "cantera/base/stringUtils.h"
#include "cantera/base/xml.h"
using namespace std;
namespace Cantera
{
MixtureFugacityTP::MixtureFugacityTP() :
ThermoPhase(),
m_Pcurrent(-1.0),
moleFractions_(0),
iState_(FLUID_GAS),
forcedState_(FLUID_UNDEFINED),
m_Tlast_ref(-1.0),
m_logc0(0.0),
m_h0_RT(0),
m_cp0_R(0),
m_g0_RT(0),
m_s0_R(0)
{
}
MixtureFugacityTP::MixtureFugacityTP(const MixtureFugacityTP& b) :
ThermoPhase(),
m_Pcurrent(-1.0),
moleFractions_(0),
iState_(FLUID_GAS),
forcedState_(FLUID_UNDEFINED),
m_Tlast_ref(-1.0),
m_logc0(0.0),
m_h0_RT(0),
m_cp0_R(0),
m_g0_RT(0),
m_s0_R(0)
{
MixtureFugacityTP::operator=(b);
}
MixtureFugacityTP&
MixtureFugacityTP::operator=(const MixtureFugacityTP& b)
{
if (&b != this) {
/*
* Mostly, this is a passthrough to the underlying
* assignment operator for the ThermoPhase parent object.
*/
ThermoPhase::operator=(b);
/*
* However, we have to handle data that we own.
*/
m_Pcurrent = b.m_Pcurrent;
moleFractions_ = b.moleFractions_;
iState_ = b.iState_;
forcedState_ = b.forcedState_;
m_Tlast_ref = b.m_Tlast_ref;
m_logc0 = b.m_logc0;
m_h0_RT = b.m_h0_RT;
m_cp0_R = b.m_cp0_R;
m_g0_RT = b.m_g0_RT;
m_s0_R = b.m_s0_R;
}
return *this;
}
ThermoPhase* MixtureFugacityTP::duplMyselfAsThermoPhase() const
{
return new MixtureFugacityTP(*this);
}
int MixtureFugacityTP::standardStateConvention() const
{
return cSS_CONVENTION_TEMPERATURE;
}
void MixtureFugacityTP::setForcedSolutionBranch(int solnBranch)
{
forcedState_ = solnBranch;
}
int MixtureFugacityTP::forcedSolutionBranch() const
{
return forcedState_;
}
int MixtureFugacityTP::reportSolnBranchActual() const
{
return iState_;
}
/*
* ---- Partial Molar Properties of the Solution -----------------
*/
void MixtureFugacityTP::getChemPotentials_RT(doublereal* muRT) const
{
getChemPotentials(muRT);
doublereal invRT = 1.0 / _RT();
for (size_t k = 0; k < m_kk; k++) {
muRT[k] *= invRT;
}
}
/*
* ----- Thermodynamic Values for the Species Standard States States ----
*/
void MixtureFugacityTP::getStandardChemPotentials(doublereal* g) const
{
_updateReferenceStateThermo();
copy(m_g0_RT.begin(), m_g0_RT.end(), g);
doublereal RT = _RT();
double tmp = log(pressure() /m_spthermo->refPressure());
for (size_t k = 0; k < m_kk; k++) {
g[k] = RT * (g[k] + tmp);
}
}
void MixtureFugacityTP::getEnthalpy_RT(doublereal* hrt) const
{
getEnthalpy_RT_ref(hrt);
}
void MixtureFugacityTP::modifyOneHf298SS(const size_t k, const doublereal Hf298New)
{
m_spthermo->modifyOneHf298(k, Hf298New);
m_Tlast_ref += 0.0001234;
}
void MixtureFugacityTP::getEntropy_R(doublereal* sr) const
{
_updateReferenceStateThermo();
copy(m_s0_R.begin(), m_s0_R.end(), sr);
double tmp = log(pressure() /m_spthermo->refPressure());
for (size_t k = 0; k < m_kk; k++) {
sr[k] -= tmp;
}
}
void MixtureFugacityTP::getGibbs_RT(doublereal* grt) const
{
_updateReferenceStateThermo();
copy(m_g0_RT.begin(), m_g0_RT.end(), grt);
double tmp = log(pressure() /m_spthermo->refPressure());
for (size_t k = 0; k < m_kk; k++) {
grt[k] += tmp;
}
}
void MixtureFugacityTP::getPureGibbs(doublereal* g) const
{
_updateReferenceStateThermo();
scale(m_g0_RT.begin(), m_g0_RT.end(), g, _RT());
double tmp = log(pressure() /m_spthermo->refPressure());
tmp *= _RT();
for (size_t k = 0; k < m_kk; k++) {
g[k] += tmp;
}
}
void MixtureFugacityTP::getIntEnergy_RT(doublereal* urt) const
{
_updateReferenceStateThermo();
copy(m_h0_RT.begin(), m_h0_RT.end(), urt);
doublereal p = pressure();
doublereal tmp = p / _RT();
doublereal v0 = _RT() / p;
for (size_t i = 0; i < m_kk; i++) {
urt[i] -= tmp * v0;
}
}
void MixtureFugacityTP::getCp_R(doublereal* cpr) const
{
_updateReferenceStateThermo();
copy(m_cp0_R.begin(), m_cp0_R.end(), cpr);
}
void MixtureFugacityTP::getStandardVolumes(doublereal* vol) const
{
_updateReferenceStateThermo();
doublereal v0 = _RT() / pressure();
for (size_t i = 0; i < m_kk; i++) {
vol[i]= v0;
}
}
/*
* ----- Thermodynamic Values for the Species Reference States ----
*/
void MixtureFugacityTP::getEnthalpy_RT_ref(doublereal* hrt) const
{
_updateReferenceStateThermo();
copy(m_h0_RT.begin(), m_h0_RT.end(), hrt);
}
void MixtureFugacityTP::getGibbs_RT_ref(doublereal* grt) const
{
_updateReferenceStateThermo();
copy(m_g0_RT.begin(), m_g0_RT.end(), grt);
}
void MixtureFugacityTP::getGibbs_ref(doublereal* g) const
{
const vector_fp& gibbsrt = gibbs_RT_ref();
scale(gibbsrt.begin(), gibbsrt.end(), g, _RT());
}
const vector_fp& MixtureFugacityTP::gibbs_RT_ref() const
{
_updateReferenceStateThermo();
return m_g0_RT;
}
void MixtureFugacityTP::getEntropy_R_ref(doublereal* er) const
{
_updateReferenceStateThermo();
copy(m_s0_R.begin(), m_s0_R.end(), er);
return;
}
void MixtureFugacityTP::getCp_R_ref(doublereal* cpr) const
{
_updateReferenceStateThermo();
copy(m_cp0_R.begin(), m_cp0_R.end(), cpr);
}
void MixtureFugacityTP::getStandardVolumes_ref(doublereal* vol) const
{
_updateReferenceStateThermo();
double pp = refPressure();
doublereal v0 = _RT() / pp;
for (size_t i = 0; i < m_kk; i++) {
vol[i]= v0;
}
}
void MixtureFugacityTP::setStateFromXML(const XML_Node& state)
{
int doTP = 0;
string comp = ctml::getChildValue(state,"moleFractions");
if (comp != "") {
// not overloaded in current object -> phase state is not calculated.
setMoleFractionsByName(comp);
doTP = 1;
} else {
comp = ctml::getChildValue(state,"massFractions");
if (comp != "") {
// not overloaded in current object -> phase state is not calculated.
setMassFractionsByName(comp);
doTP = 1;
}
}
double t = temperature();
if (state.hasChild("temperature")) {
t = ctml::getFloat(state, "temperature", "temperature");
doTP = 1;
}
if (state.hasChild("pressure")) {
double p = ctml::getFloat(state, "pressure", "pressure");
setState_TP(t, p);
} else if (state.hasChild("density")) {
double rho = ctml::getFloat(state, "density", "density");
setState_TR(t, rho);
} else if (doTP) {
double rho = Phase::density();
setState_TR(t, rho);
}
}
void MixtureFugacityTP::initThermo()
{
initLengths();
ThermoPhase::initThermo();
}
void MixtureFugacityTP::initLengths()
{
m_kk = nSpecies();
moleFractions_.resize(m_kk, 0.0);
moleFractions_[0] = 1.0;
m_h0_RT.resize(m_kk, 0.0);
m_cp0_R.resize(m_kk, 0.0);
m_g0_RT.resize(m_kk, 0.0);
m_s0_R.resize(m_kk, 0.0);
}
void MixtureFugacityTP::setTemperature(const doublereal temp)
{
_updateReferenceStateThermo();
setState_TR(temperature(), density());
}
void MixtureFugacityTP::setPressure(doublereal p)
{
setState_TP(temperature(), p);
// double chemPot[5], mf[5];
// getMoleFractions(mf);
// getChemPotentials(chemPot);
// for (int i = 0; i < m_kk; i++) {
// printf(" MixFug:setPres: mu(%d = %g) = %18.8g\n", i, mf[i], chemPot[i]);
// }
}
void MixtureFugacityTP::setMassFractions(const doublereal* const y)
{
Phase::setMassFractions(y);
getMoleFractions(DATA_PTR(moleFractions_));
}
void MixtureFugacityTP::setMassFractions_NoNorm(const doublereal* const y)
{
Phase::setMassFractions_NoNorm(y);
getMoleFractions(DATA_PTR(moleFractions_));
}
void MixtureFugacityTP::setMoleFractions(const doublereal* const x)
{
Phase::setMoleFractions(x);
getMoleFractions(DATA_PTR(moleFractions_));
}
void MixtureFugacityTP::setMoleFractions_NoNorm(const doublereal* const x)
{
Phase::setMoleFractions_NoNorm(x);
getMoleFractions(DATA_PTR(moleFractions_));
}
void MixtureFugacityTP::setConcentrations(const doublereal* const c)
{
Phase::setConcentrations(c);
getMoleFractions(DATA_PTR(moleFractions_));
}
void MixtureFugacityTP::setMoleFractions_NoState(const doublereal* const x)
{
Phase::setMoleFractions(x);
getMoleFractions(DATA_PTR(moleFractions_));
updateMixingExpressions();
}
void MixtureFugacityTP::calcDensity()
{
throw NotImplementedError("MixtureFugacityTP::calcDensity() "
"called, but EOS for phase is not known");
}
void MixtureFugacityTP::setState_TP(doublereal t, doublereal pres)
{
/*
* A pretty tricky algorithm is needed here, due to problems involving
* standard states of real fluids. For those cases you need
* to combine the T and P specification for the standard state, or else
* you may venture into the forbidden zone, especially when nearing the
* triple point.
* Therefore, we need to do the standard state thermo calc with the
* (t, pres) combo.
*/
getMoleFractions(DATA_PTR(moleFractions_));
Phase::setTemperature(t);
_updateReferenceStateThermo();
// Depends on the mole fractions and the temperature
updateMixingExpressions();
// setPressure(pres);
m_Pcurrent = pres;
// double mmw = meanMolecularWeight();
if (forcedState_ == FLUID_UNDEFINED) {
double rhoNow = Phase::density();
double rho = densityCalc(t, pres, iState_, rhoNow);
if (rho > 0.0) {
Phase::setDensity(rho);
m_Pcurrent = pres;
iState_ = phaseState(true);
} else {
if (rho < -1.5) {
rho = densityCalc(t, pres, FLUID_UNDEFINED , rhoNow);
if (rho > 0.0) {
Phase::setDensity(rho);
m_Pcurrent = pres;
iState_ = phaseState(true);
} else {
throw CanteraError("MixtureFugacityTP::setState_TP()", "neg rho");
}
} else {
throw CanteraError("MixtureFugacityTP::setState_TP()", "neg rho");
}
}
} else if (forcedState_ == FLUID_GAS) {
// Normal density calculation
if (iState_ < FLUID_LIQUID_0) {
double rhoNow = Phase::density();
double rho = densityCalc(t, pres, iState_, rhoNow);
if (rho > 0.0) {
Phase::setDensity(rho);
m_Pcurrent = pres;
iState_ = phaseState(true);
if (iState_ >= FLUID_LIQUID_0) {
throw CanteraError("MixtureFugacityTP::setState_TP()", "wrong state");
}
} else {
throw CanteraError("MixtureFugacityTP::setState_TP()", "neg rho");
}
}
} else if (forcedState_ > FLUID_LIQUID_0) {
if (iState_ >= FLUID_LIQUID_0) {
double rhoNow = Phase::density();
double rho = densityCalc(t, pres, iState_, rhoNow);
if (rho > 0.0) {
Phase::setDensity(rho);
m_Pcurrent = pres;
iState_ = phaseState(true);
if (iState_ == FLUID_GAS) {
throw CanteraError("MixtureFugacityTP::setState_TP()", "wrong state");
}
} else {
throw CanteraError("MixtureFugacityTP::setState_TP()", "neg rho");
}
}
}
//setTemperature(t);
//setPressure(pres);
//calcDensity();
}
void MixtureFugacityTP::setState_TR(doublereal T, doublereal rho)
{
getMoleFractions(DATA_PTR(moleFractions_));
Phase::setTemperature(T);
_updateReferenceStateThermo();
Phase::setDensity(rho);
doublereal mv = molarVolume();
// depends on mole fraction and temperature
updateMixingExpressions();
m_Pcurrent = pressureCalc(T, mv);
iState_ = phaseState(true);
// printf("setState_TR: state at T = %g, rho = %g, mv = %g, P = %20.13g, iState = %d\n", T, rho, mv, m_Pcurrent, iState_);
}
void MixtureFugacityTP::setState_TPX(doublereal t, doublereal p, const doublereal* x)
{
setMoleFractions_NoState(x);
setState_TP(t,p);
}
void MixtureFugacityTP::initThermoXML(XML_Node& phaseNode, const std::string& id_)
{
MixtureFugacityTP::initLengths();
//m_VPSS_ptr->initThermo();
// m_VPSS_ptr->initThermoXML(phaseNode, id);
ThermoPhase::initThermoXML(phaseNode, id_);
}
doublereal MixtureFugacityTP::z() const
{
doublereal p = pressure();
doublereal rho = density();
doublereal mmw = meanMolecularWeight();
doublereal molarV = mmw / rho;
doublereal rt = _RT();
return p * molarV / rt;
}
doublereal MixtureFugacityTP::sresid() const
{
throw CanteraError("MixtureFugacityTP::sresid()", "Base Class: not implemented");
return 0.0;
}
doublereal MixtureFugacityTP::hresid() const
{
throw CanteraError("MixtureFugacityTP::hresid()", "Base Class: not implemented");
return 0.0;
}
doublereal MixtureFugacityTP::psatEst(doublereal TKelvin) const
{
doublereal tcrit = critTemperature();
doublereal pcrit = critPressure();
doublereal tt = tcrit/TKelvin;
if (tt < 1.0) {
return pcrit;
}
doublereal lpr = -0.8734*tt*tt - 3.4522*tt + 4.2918;
return pcrit*exp(lpr);
}
doublereal MixtureFugacityTP::liquidVolEst(doublereal TKelvin, doublereal& pres) const
{
throw CanteraError("MixtureFugacityTP::liquidVolEst()", "unimplemented");
return 0.0;
}
doublereal MixtureFugacityTP::densityCalc(doublereal TKelvin, doublereal presPa,
int phase, doublereal rhoguess)
{
double tcrit = critTemperature();
doublereal mmw = meanMolecularWeight();
// double pcrit = critPressure();
// doublereal deltaGuess = 0.0;
if (rhoguess == -1.0) {
if (phase != -1) {
if (TKelvin > tcrit) {
rhoguess = presPa * mmw / (GasConstant * TKelvin);
} else {
if (phase == FLUID_GAS || phase == FLUID_SUPERCRIT) {
rhoguess = presPa * mmw / (GasConstant * TKelvin);
} else if (phase >= FLUID_LIQUID_0) {
double lqvol = liquidVolEst(TKelvin, presPa);
rhoguess = mmw / lqvol;
}
}
} else {
/*
* Assume the Gas phase initial guess, if nothing is
* specified to the routine
*/
rhoguess = presPa * mmw / (GasConstant * TKelvin);
}
}
double molarVolBase = mmw / rhoguess;
double molarVolLast = molarVolBase;
double vc = mmw / critDensity();
/*
* molar volume of the spinodal at the current temperature and mole fractions. this will
* be updated as we go.
*/
double molarVolSpinodal = vc;
doublereal pcheck = 1.0E-30 + 1.0E-8 * presPa;
doublereal presBase, dpdVBase, delMV;
bool conv = false;
/*
* We start on one side of the vc and stick with that side
*/
bool gasSide = molarVolBase > vc;
if (gasSide) {
molarVolLast = (GasConstant * TKelvin)/presPa;
} else {
molarVolLast = liquidVolEst(TKelvin, presPa);
}
/*
* OK, now we do a small solve to calculate the molar volume given the T,P value.
* The algorithm is taken from dfind()
*/
for (int n = 0; n < 200; n++) {
/*
* Calculate the predicted reduced pressure, pred0, based on the
* current tau and dd.
*/
/*
* Calculate the derivative of the predicted pressure
* wrt the molar volume.
* This routine also returns the pressure, presBase
*/
dpdVBase = dpdVCalc(TKelvin, molarVolBase, presBase);
/*
* If dpdV is positve, then we are in the middle of the
* 2 phase region and beyond the spinodal stability curve. We need to adjust
* the initial guess outwards and start a new iteration.
*/
if (dpdVBase >= 0.0) {
if (TKelvin > tcrit) {
throw CanteraError("", "confused");
}
/*
* TODO Spawn a calculation for the value of the spinodal point that is
* very accurate. Answer the question as to wethera solution is
* possible on the current side of the vapor dome.
*/
if (gasSide) {
if (molarVolBase >= vc) {
molarVolSpinodal = molarVolBase;
molarVolBase = 0.5 * (molarVolLast + molarVolSpinodal);
} else {
molarVolBase = 0.5 * (molarVolLast + molarVolSpinodal);
}
} else {
if (molarVolBase <= vc) {
molarVolSpinodal = molarVolBase;
molarVolBase = 0.5 * (molarVolLast + molarVolSpinodal);
} else {
molarVolBase = 0.5 * (molarVolLast + molarVolSpinodal);
}
}
continue;
}
/*
* Check for convergence
*/
if (fabs(presBase-presPa) < pcheck) {
conv = true;
break;
}
/*
* Dampen and crop the update
*/
doublereal dpdV = dpdVBase;
if (n < 10) {
dpdV = dpdVBase * 1.5;
}
// if (dpdV > -0.001) dpdV = -0.001;
/*
* Formulate the update to the molar volume by
* Newton's method. Then, crop it to a max value
* of 0.1 times the current volume
*/
delMV = - (presBase - presPa) / dpdV;
if (!gasSide || delMV < 0.0) {
if (fabs(delMV) > 0.2 * molarVolBase) {
delMV = delMV / fabs(delMV) * 0.2 * molarVolBase;
}
}
/*
* Only go 1/10 the way towards the spinodal at any one time.
*/
if (TKelvin < tcrit) {
if (gasSide) {
if (delMV < 0.0) {
if (-delMV > 0.5 * (molarVolBase - molarVolSpinodal)) {
delMV = - 0.5 * (molarVolBase - molarVolSpinodal);
}
}
} else {
if (delMV > 0.0) {
if (delMV > 0.5 * (molarVolSpinodal - molarVolBase)) {
delMV = 0.5 * (molarVolSpinodal - molarVolBase);
}
}
}
}
/*
* updated the molar volume value
*/
molarVolLast = molarVolBase;
molarVolBase += delMV;
if (fabs(delMV/molarVolBase) < 1.0E-14) {
conv = true;
break;
}
/*
* Check for negative molar volumes
*/
if (molarVolBase <= 0.0) {
molarVolBase = std::min(1.0E-30, fabs(delMV*1.0E-4));
}
}
/*
* Check for convergence, and return 0.0 if it wasn't achieved.
*/
double densBase = 0.0;
if (! conv) {
molarVolBase = 0.0;
throw CanteraError("MixtureFugacityTP::densityCalc()", "Process didnot converge");
} else {
densBase = mmw / molarVolBase;
}
return densBase;
}
void MixtureFugacityTP::updateMixingExpressions()
{
}
MixtureFugacityTP::spinodalFunc::spinodalFunc(MixtureFugacityTP* tp) :
ResidEval(),
m_tp(tp)
{
}
int MixtureFugacityTP::spinodalFunc::evalSS(const doublereal t, const doublereal* const y,
doublereal* const r)
{
int status = 0;
doublereal molarVol = y[0];
doublereal tt = m_tp->temperature();
doublereal pp;
doublereal val = m_tp->dpdVCalc(tt, molarVol, pp);
r[0] = val;
return status;
}
int MixtureFugacityTP::corr0(doublereal TKelvin, doublereal pres, doublereal& densLiqGuess,
doublereal& densGasGuess, doublereal& liqGRT, doublereal& gasGRT)
{
int retn = 0;
doublereal densLiq = densityCalc(TKelvin, pres, FLUID_LIQUID_0, densLiqGuess);
if (densLiq <= 0.0) {
// throw Cantera::CanteraError("MixtureFugacityTP::corr0",
// "Error occurred trying to find liquid density at (T,P) = "
// + Cantera::fp2str(TKelvin) + " " + Cantera::fp2str(pres));
retn = -1;
} else {
densLiqGuess = densLiq;
setState_TR(TKelvin, densLiq);
liqGRT = gibbs_mole() / _RT();
}
doublereal densGas = densityCalc(TKelvin, pres, FLUID_GAS, densGasGuess);
if (densGas <= 0.0) {
//throw Cantera::CanteraError("MixtureFugacityTP::corr0",
// "Error occurred trying to find gas density at (T,P) = "
// + Cantera::fp2str(TKelvin) + " " + Cantera::fp2str(pres));
if (retn == -1) {
throw Cantera::CanteraError("MixtureFugacityTP::corr0",
"Error occurred trying to find gas density at (T,P) = "
+ Cantera::fp2str(TKelvin) + " " + Cantera::fp2str(pres));
}
retn = -2;
} else {
densGasGuess = densGas;
setState_TR(TKelvin, densGas);
gasGRT = gibbs_mole() / _RT();
}
// delGRT = gibbsLiqRT - gibbsGasRT;
return retn;
}
int MixtureFugacityTP::phaseState(bool checkState) const
{
int state = iState_;
if (checkState) {
double t = temperature();
double tcrit = critTemperature();
double rhocrit = critDensity();
if (t >= tcrit) {
return FLUID_SUPERCRIT;
}
double tmid = tcrit - 100.;
if (tmid < 0.0) {
tmid = tcrit / 2.0;
}
double pp = psatEst(tmid);
double mmw = meanMolecularWeight();
double molVolLiqTmid = liquidVolEst(tmid, pp);
double molVolGasTmid = GasConstant * tmid / (pp);
double densLiqTmid = mmw / molVolLiqTmid;
double densGasTmid = mmw / molVolGasTmid;
double densMidTmid = 0.5 * (densLiqTmid + densGasTmid);
doublereal rhoMid = rhocrit + (t - tcrit) * (rhocrit - densMidTmid) / (tcrit - tmid);
double rho = density();
int iStateGuess = FLUID_LIQUID_0;
if (rho < rhoMid) {
iStateGuess = FLUID_GAS;
}
double molarVol = mmw / rho;
double presCalc;
double dpdv = dpdVCalc(t, molarVol, presCalc);
if (dpdv < 0.0) {
state = iStateGuess;
} else {
state = FLUID_UNSTABLE;
}
}
return state;
}
doublereal MixtureFugacityTP::densSpinodalLiquid() const
{
throw CanteraError("", "unimplmented");
return 0.0;
}
doublereal MixtureFugacityTP::densSpinodalGas() const
{
throw CanteraError("", "unimplmented");
return 0.0;
}
doublereal MixtureFugacityTP::satPressure(doublereal TKelvin)
{
doublereal molarVolGas;
doublereal molarVolLiquid;
return calculatePsat(TKelvin, molarVolGas, molarVolLiquid);
}
doublereal MixtureFugacityTP::calculatePsat(doublereal TKelvin, doublereal& molarVolGas,
doublereal& molarVolLiquid)
{
/*
* The algorithm for this routine has undergone quite a bit of work. It probably needs more work.
* However, it seems now to be fairly robust.
* The key requirement is to find an initial pressure where both the liquid and the gas exist. This
* is not as easy as it sounds, and it gets exceedingly hard as the critical temperature is approached
* from below.
* Once we have this initial state, then we seek to equilibrate the gibbs free energies of the
* gas and liquid and use the formula
*
* dp = VdG
*
* to create an update condition for deltaP using
*
* - (Gliq - Ggas) = (Vliq - Vgas) (deltaP)
*
* @TODO Suggestions for the future would be to switch it to an algorithm that uses the gas molar volume
* and the liquid molar volumes as the fundamental unknowns.
*/
// we need this because this is a non-const routine that is public
setTemperature(TKelvin);
double tcrit = critTemperature();
double RhoLiquid, RhoGas;
double RhoLiquidGood, RhoGasGood;
double densSave = density();
double tempSave = temperature();
double pres;
doublereal mw = meanMolecularWeight();
if (TKelvin < tcrit) {
pres = psatEst(TKelvin);
// trial value = Psat from correlation
doublereal volLiquid = liquidVolEst(TKelvin, pres);
RhoLiquidGood = mw / volLiquid;
RhoGasGood = pres * mw / (GasConstant * TKelvin);
doublereal delGRT = 1.0E6;
doublereal liqGRT, gasGRT;
int stab;
doublereal presLast = pres;
/*
* First part of the calculation involves finding a pressure at which the
* gas and the liquid state coexists.
*/
doublereal presLiquid = 0.;
doublereal presGas;
doublereal presBase = pres;
bool foundLiquid = false;
bool foundGas = false;
doublereal densLiquid = densityCalc(TKelvin, presBase, FLUID_LIQUID_0, RhoLiquidGood);
if (densLiquid > 0.0) {
foundLiquid = true;
presLiquid = pres;
RhoLiquidGood = densLiquid;
}
if (!foundLiquid) {
for (int i = 0; i < 50; i++) {
pres = 1.1 * pres;
densLiquid = densityCalc(TKelvin, pres, FLUID_LIQUID_0, RhoLiquidGood);
if (densLiquid > 0.0) {
foundLiquid = true;
presLiquid = pres;
RhoLiquidGood = densLiquid;
break;
}
}
}
pres = presBase;
doublereal densGas = densityCalc(TKelvin, pres, FLUID_GAS, RhoGasGood);
if (densGas <= 0.0) {
foundGas = false;
} else {
foundGas = true;
presGas = pres;
RhoGasGood = densGas;
}
if (!foundGas) {
for (int i = 0; i < 50; i++) {
pres = 0.9 * pres;
densGas = densityCalc(TKelvin, pres, FLUID_GAS, RhoGasGood);
if (densGas > 0.0) {
foundGas = true;
presGas = pres;
RhoGasGood = densGas;
break;
}
}
}
if (foundGas && foundLiquid) {
if (presGas != presLiquid) {
pres = 0.5 * (presLiquid + presGas);
bool goodLiq;
bool goodGas;
for (int i = 0; i < 50; i++) {
densLiquid = densityCalc(TKelvin, pres, FLUID_LIQUID_0, RhoLiquidGood);
if (densLiquid <= 0.0) {
goodLiq = false;
} else {
goodLiq = true;
RhoLiquidGood = densLiquid;
presLiquid = pres;
}
densGas = densityCalc(TKelvin, pres, FLUID_GAS, RhoGasGood);
if (densGas <= 0.0) {
goodGas = false;
} else {
goodGas = true;
RhoGasGood = densGas;
presGas = pres;
}
if (goodGas && goodLiq) {
break;
}
if (!goodLiq && !goodGas) {
pres = 0.5 * (pres + presLiquid);
}
if (goodLiq || goodGas) {
pres = 0.5 * (presLiquid + presGas);
}
}
}
}
if (!foundGas || !foundLiquid) {
printf("error coundn't find a starting pressure\n");
return 0.0;
}
if (presGas != presLiquid) {
printf("error coundn't find a starting pressure\n");
return 0.0;
}
pres = presGas;
presLast = pres;
RhoGas = RhoGasGood;
RhoLiquid = RhoLiquidGood;
/*
* Now that we have found a good pressure we can proceed with the algorithm.
*/
for (int i = 0; i < 20; i++) {
stab = corr0(TKelvin, pres, RhoLiquid, RhoGas, liqGRT, gasGRT);
if (stab == 0) {
presLast = pres;
delGRT = liqGRT - gasGRT;
doublereal delV = mw * (1.0/RhoLiquid - 1.0/RhoGas);
doublereal dp = - delGRT * GasConstant * TKelvin / delV;
if (fabs(dp) > 0.1 * pres) {
if (dp > 0.0) {
dp = 0.1 * pres;
} else {
dp = -0.1 * pres;
}
}
pres += dp;
} else if (stab == -1) {
delGRT = 1.0E6;
if (presLast > pres) {
pres = 0.5 * (presLast + pres);
} else {
// we are stuck here - try this
pres = 1.1 * pres;
}
} else if (stab == -2) {
if (presLast < pres) {
pres = 0.5 * (presLast + pres);
} else {
// we are stuck here - try this
pres = 0.9 * pres;
}
}
molarVolGas = mw / RhoGas;
molarVolLiquid = mw / RhoLiquid;
if (fabs(delGRT) < 1.0E-8) {
// converged
break;
}
}
molarVolGas = mw / RhoGas;
molarVolLiquid = mw / RhoLiquid;
// Put the fluid in the desired end condition
setState_TR(tempSave, densSave);
return pres;
} else {
pres = critPressure();
setState_TP(TKelvin, pres);
RhoGas = density();
molarVolGas = mw / RhoGas;
molarVolLiquid = molarVolGas;
setState_TR(tempSave, densSave);
}
return pres;
}
doublereal MixtureFugacityTP::pressureCalc(doublereal TKelvin, doublereal molarVol) const
{
throw CanteraError("MixtureFugacityTP::pressureCalc", "unimplemented");
return 0.0;
}
doublereal MixtureFugacityTP::dpdVCalc(doublereal TKelvin, doublereal molarVol, doublereal& presCalc) const
{
throw CanteraError("MixtureFugacityTP::dpdVCalc", "unimplemented");
return 0.0;
}
void MixtureFugacityTP::_updateReferenceStateThermo() const
{
double Tnow = temperature();
// If the temperature has changed since the last time these
// properties were computed, recompute them.
if (m_Tlast_ref != Tnow) {
m_spthermo->update(Tnow, &m_cp0_R[0], &m_h0_RT[0], &m_s0_R[0]);
m_Tlast_ref = Tnow;
// update the species Gibbs functions
for (size_t k = 0; k < m_kk; k++) {
m_g0_RT[k] = m_h0_RT[k] - m_s0_R[k];
}
doublereal pref = refPressure();
if (pref <= 0.0) {
throw CanteraError("MixtureFugacityTP::_updateReferenceStateThermo()", "neg ref pressure");
}
m_logc0 = log(pref/(GasConstant * Tnow));
}
}
}
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