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Fix speed issues with PQ and QT for cubics; disable spinodal calcs (slow)

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closes #1144
closes #1142
This commit is contained in:
Ian Bell
2016-07-05 21:44:25 -06:00
parent f5e4e3faea
commit c5f0d076c8
2 changed files with 31 additions and 2 deletions
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27
src/Backends/Cubics/CubicBackend.cpp
View File

@@ -94,6 +94,25 @@ void CoolProp::AbstractCubicBackend::get_critical_point_starting_values(double &
delta0 *= rhor_GERGlike/rhomolar_reducing();
tau0 *= T_reducing()/Tr_GERGlike;
}
CoolPropDbl CoolProp::AbstractCubicBackend::calc_pressure_nocache(CoolPropDbl T, CoolPropDbl rhomolar){
AbstractCubic *cubic = get_cubic().get();
double tau = cubic->T_r / T;
double delta = rhomolar / cubic->rho_r;
return _rhomolar*gas_constant()*_T*(1+delta*cubic->alphar(tau, delta, this->get_mole_fractions_doubleref(), 0, 1));
}
void CoolProp::AbstractCubicBackend::update_DmolarT()
{
// Only works for now when phase is specified
if (this->imposed_phase_index != iphase_not_imposed){
_p = calc_pressure_nocache(_T, _rhomolar);
_Q = -1;
_phase = imposed_phase_index;
}
else{
// Pass call to parent class
HelmholtzEOSMixtureBackend::update(DmolarT_INPUTS, this->_rhomolar, this->_T);
}
};
CoolPropDbl CoolProp::AbstractCubicBackend::calc_alphar_deriv_nocache(const int nTau, const int nDelta, const std::vector<CoolPropDbl> & mole_fractions, const CoolPropDbl &tau, const CoolPropDbl &delta){
bool cache_values = true;
@@ -166,6 +185,7 @@ void CoolProp::AbstractCubicBackend::update(CoolProp::input_pairs input_pair, do
case PQ_INPUTS:
_p = value1; _Q = value2; saturation(input_pair); break;
case DmolarT_INPUTS:
_rhomolar = value1; _T = value2; update_DmolarT(); break;
case SmolarT_INPUTS:
case DmolarP_INPUTS:
case DmolarHmolar_INPUTS:
@@ -175,7 +195,6 @@ void CoolProp::AbstractCubicBackend::update(CoolProp::input_pairs input_pair, do
case PSmolar_INPUTS:
case PUmolar_INPUTS:
case HmolarSmolar_INPUTS:
case QSmolar_INPUTS:
case HmolarQ_INPUTS:
case DmolarQ_INPUTS:
@@ -318,6 +337,8 @@ void CoolProp::AbstractCubicBackend::saturation(CoolProp::input_pairs inputs){
_T = Ts;
rhoL = resid.deltaL*cubic->T_r;
rhoV = resid.deltaV*cubic->T_r;
this->SatL->update(DmolarT_INPUTS, rhoL, _T);
this->SatV->update(DmolarT_INPUTS, rhoV, _T);
}
else{
HelmholtzEOSMixtureBackend::update(PQ_INPUTS, _p, _Q);
@@ -328,7 +349,9 @@ void CoolProp::AbstractCubicBackend::saturation(CoolProp::input_pairs inputs){
if (is_pure_or_pseudopure){
SaturationResidual resid(this, inputs, _T);
static std::string errstr;
std::vector<double> roots = spinodal_densities();
// ** Spinodal densities is disabled for now because it is VERY slow :(
// std::vector<double> roots = spinodal_densities();
std::vector<double> roots;
// Estimate pressure from the acentric factor relationship
double neg_log10_pr = (acentric + 1) / (1 / 0.7 - 1)*(Tc / _T - 1);

6
src/Backends/Cubics/CubicBackend.h
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@@ -114,6 +114,12 @@ public:
CoolPropDbl calc_alphar_deriv_nocache(const int nTau, const int nDelta, const std::vector<CoolPropDbl> & mole_fractions, const CoolPropDbl &tau, const CoolPropDbl &delta);
/// Calculate the pressure in most computationally efficient manner
CoolPropDbl calc_pressure_nocache(CoolPropDbl T, CoolPropDbl rhomolar);
/// Update the state for DT inputs if phase is imposed. Otherwise delegate to base class
virtual void update_DmolarT();
virtual void update(CoolProp::input_pairs input_pair, double value1, double value2);
/** Use the cubic EOS to solve for density