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Implemented new gas constant normalization method - seems to work well and doesn't touch pure fluid properties

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Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
This commit is contained in:
Ian Bell
2014-09-10 15:44:01 +02:00
parent 86f52bdf4e
commit 883b7a3f09
4 changed files with 30 additions and 15 deletions
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2
src/Backends/Helmholtz/Configuration.cpp
View File

@@ -16,6 +16,8 @@ bool get_config_bool(configuration_keys key)
switch(key)
{
case NORMALIZE_GAS_CONSTANTS:
return false;
case NORMALIZE_GAS_CONSTANTS2:
return true;
default:
throw ValueError(format("%d is invalid key to get_config_bool",key));

2
src/Backends/Helmholtz/Configuration.h
View File

@@ -4,7 +4,7 @@
#include "Exceptions.h"
#include "CoolPropTools.h"
enum configuration_keys {NORMALIZE_GAS_CONSTANTS};
enum configuration_keys {NORMALIZE_GAS_CONSTANTS, NORMALIZE_GAS_CONSTANTS2};
namespace CoolProp
{

14
src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
View File

@@ -171,11 +171,11 @@ long double HelmholtzEOSMixtureBackend::calc_gas_constant(void)
return components[0]->gas_constant();
}
else{
if (get_config_bool(NORMALIZE_GAS_CONSTANTS)){
if (get_config_bool(NORMALIZE_GAS_CONSTANTS) || get_config_bool(NORMALIZE_GAS_CONSTANTS2)){
return R_u_CODATA;
}
else{
// mass fraction weighet average of the components
// mass fraction weighted average of the components
double summer = 0;
for (unsigned int i = 0; i < components.size(); ++i)
{
@@ -1954,7 +1954,7 @@ long double HelmholtzEOSMixtureBackend::calc_cvmolar(void)
// Calculate derivatives if needed, or just use cached values
long double d2ar_dTau2 = d2alphar_dTau2();
long double d2a0_dTau2 = d2alpha0_dTau2();
long double R_u = static_cast<double>(_gas_constant);
long double R_u = gas_constant();
// Get cv
_cvmolar = -R_u*pow(_tau.pt(),2)*(d2ar_dTau2 + d2a0_dTau2);
@@ -1973,7 +1973,7 @@ long double HelmholtzEOSMixtureBackend::calc_cpmolar(void)
long double d2ar_dDelta2 = d2alphar_dDelta2();
long double d2ar_dDelta_dTau = d2alphar_dDelta_dTau();
long double d2ar_dTau2 = d2alphar_dTau2();
long double R_u = static_cast<double>(_gas_constant);
long double R_u = gas_constant();
// Get cp
_cpmolar = R_u*(-pow(_tau.pt(),2)*(d2ar_dTau2 + d2a0_dTau2)+pow(1+_delta.pt()*dar_dDelta-_delta.pt()*_tau.pt()*d2ar_dDelta_dTau,2)/(1+2*_delta.pt()*dar_dDelta+pow(_delta.pt(),2)*d2ar_dDelta2));
@@ -1988,7 +1988,7 @@ long double HelmholtzEOSMixtureBackend::calc_cpmolar_idealgas(void)
// Calculate derivatives if needed, or just use cached values
long double d2a0_dTau2 = d2alpha0_dTau2();
long double R_u = static_cast<double>(_gas_constant);
long double R_u = gas_constant();
// Get cp of the ideal gas
return R_u*(1+(-pow(_tau.pt(),2))*d2a0_dTau2);
@@ -2090,6 +2090,10 @@ void HelmholtzEOSMixtureBackend::calc_all_alphar_deriv_cache(const std::vector<l
for (std::size_t i = 0; i < N; ++i){
HelmholtzDerivatives derivs = components[i]->pEOS->alphar.all(tau, delta);
long double xi = mole_fractions[i];
long double R_u_ratio = 1;
if (get_config_bool(NORMALIZE_GAS_CONSTANTS2)){
R_u_ratio = components[0]->pEOS->R_u/R_u_CODATA;
}
summer_base += xi*derivs.alphar;
summer_dDelta += xi*derivs.dalphar_ddelta;
summer_dTau += xi*derivs.dalphar_dtau;