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Added refinement of the phase envelope, PQ and TQ work for saturation

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See https://github.com/CoolProp/CoolProp/issues/133

Closes https://github.com/CoolProp/CoolProp/issues/143

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
This commit is contained in:
Ian Bell
2014-09-15 14:19:22 +02:00
parent bdb7c2defc
commit 5f723ce585
4 changed files with 89 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
src/Backends/Helmholtz/FlashRoutines.cpp
View File

@@ -427,6 +427,10 @@ void FlashRoutines::PT_Q_flash_mixtures(HelmholtzEOSMixtureBackend &HEOS, parame
std::size_t &imax = solutions[0];
// Shift the solution if needed to ensure that imax+2 and imax-1 are both in range
if (imax+2 >= env.T.size()){ imax--; }
else if (imax-1 < 0){ imax++; }
SaturationSolvers::newton_raphson_saturation NR;
SaturationSolvers::newton_raphson_saturation_options IO;
@@ -435,13 +439,16 @@ void FlashRoutines::PT_Q_flash_mixtures(HelmholtzEOSMixtureBackend &HEOS, parame
IO.imposed_variable = SaturationSolvers::newton_raphson_saturation_options::P_IMPOSED;
// p -> rhomolar_vap
IO.rhomolar_vap = CubicInterp(env.p, env.rhomolar_vap, imax-1, imax, imax+1, imax+2, static_cast<long double>(IO.p));
IO.T = CubicInterp(env.rhomolar_vap, env.T, imax-1, imax, imax+1, imax+2, IO.rhomolar_vap);
}
else if (other == iT){
IO.T = HEOS._T;
IO.imposed_variable = SaturationSolvers::newton_raphson_saturation_options::T_IMPOSED;
// p -> rhomolar_vap
// T -> rhomolar_vap
IO.rhomolar_vap = CubicInterp(env.T, env.rhomolar_vap, imax-1, imax, imax+1, imax+2, static_cast<long double>(IO.T));
IO.p = CubicInterp(env.rhomolar_vap, env.p, imax-1, imax, imax+1, imax+2, IO.rhomolar_vap);
}
IO.rhomolar_liq = CubicInterp(env.rhomolar_vap, env.rhomolar_liq, imax-1, imax, imax+1, imax+2, IO.rhomolar_vap);
if (quality == SATURATED_VAPOR){
IO.bubble_point = false;
@@ -458,9 +465,13 @@ void FlashRoutines::PT_Q_flash_mixtures(HelmholtzEOSMixtureBackend &HEOS, parame
IO.bubble_point = true;
IO.x = HEOS.get_mole_fractions(); // Because Q = 0
IO.y.resize(IO.x.size());
// Phases are inverted, so "liquid" is actually the lighter phase
std::swap(IO.rhomolar_liq, IO.rhomolar_vap);
for (std::size_t i = 0; i < IO.y.size()-1; ++i) // First N-1 elements
{
IO.y[i] = CubicInterp(env.rhomolar_vap, env.x[i], imax-1, imax, imax+1, imax+2, IO.rhomolar_vap);
// Phases are inverted, so liquid mole fraction (x) of phase envelope is actually the vapor phase mole fraction
// Use the liquid density as well
IO.y[i] = CubicInterp(env.rhomolar_vap, env.x[i], imax-1, imax, imax+1, imax+2, IO.rhomolar_liq);
}
IO.y[IO.y.size()-1] = 1 - std::accumulate(IO.y.begin(), IO.y.end()-1, 0.0);
NR.call(HEOS, IO.x, IO.y, IO);

68
src/Backends/Helmholtz/PhaseEnvelopeRoutines.cpp
View File

@@ -145,8 +145,8 @@ void PhaseEnvelopeRoutines::build(HelmholtzEOSMixtureBackend &HEOS)
}
}
catch(std::exception &e){
std::cout << e.what() << std::endl;
std::cout << IO.T << " " << IO.p << std::endl;
//std::cout << e.what() << std::endl;
//std::cout << IO.T << " " << IO.p << std::endl;
// Try again, but with a smaller step
IO.rhomolar_vap /= factor;
factor = 1 + (factor-1)/2;
@@ -199,14 +199,73 @@ void PhaseEnvelopeRoutines::build(HelmholtzEOSMixtureBackend &HEOS)
factor = std::max(factor, static_cast<long double>(1.01));
// Stop if the pressure is below the starting pressure
if (iter > 4 && IO.p < env.p[0]){ env.built = true; std::cout << format("envelope built.\n"); return; }
if (iter > 4 && IO.p < env.p[0]){
env.built = true;
std::cout << format("envelope built.\n");
// Now we refine the phase envelope to add some points in places that are still pretty rough
// Can be re-enabled by just uncommenting the following line
refine(HEOS);
return;
}
// Reset the failure counter
failure_count = 0;
}
}
void PhaseEnvelopeRoutines::refine(HelmholtzEOSMixtureBackend &HEOS)
{
PhaseEnvelopeData &env = HEOS.PhaseEnvelope;
SaturationSolvers::newton_raphson_saturation NR;
SaturationSolvers::newton_raphson_saturation_options IO;
IO.imposed_variable = SaturationSolvers::newton_raphson_saturation_options::RHOV_IMPOSED;
IO.bubble_point = false;
IO.y = HEOS.get_mole_fractions();
std::size_t i = 0;
do{
// Don't do anything if change in density is small enough
if (std::abs(env.rhomolar_vap[i]/env.rhomolar_vap[i+1]-1) < 0.2){ i++; continue; }
double rhomolar_vap_start = env.rhomolar_vap[i],
rhomolar_vap_end = env.rhomolar_vap[i+1];
// Ok, now we are going to do some more refining in this step
for (double rhomolar_vap = rhomolar_vap_start*1.1; rhomolar_vap < rhomolar_vap_end; rhomolar_vap *= 1.1)
{
IO.rhomolar_vap = rhomolar_vap;
IO.x.resize(IO.y.size());
if (i < env.T.size()-3){
IO.T = CubicInterp(env.rhomolar_vap, env.T, i, i+1, i+2, i+3, IO.rhomolar_vap);
IO.rhomolar_liq = CubicInterp(env.rhomolar_vap, env.rhomolar_liq, i, i+1, i+2, i+3, IO.rhomolar_vap);
for (std::size_t j = 0; j < IO.x.size()-1; ++j){ // First N-1 elements
IO.x[j] = CubicInterp(env.rhomolar_vap, env.x[j], i, i+1, i+2, i+3, IO.rhomolar_vap);
}
}
else{
IO.T = CubicInterp(env.rhomolar_vap, env.T, i, i-1, i-2, i-3, IO.rhomolar_vap);
IO.rhomolar_liq = CubicInterp(env.rhomolar_vap, env.rhomolar_liq, i, i-1, i-2, i-3, IO.rhomolar_vap);
for (std::size_t j = 0; j < IO.x.size()-1; ++j){ // First N-1 elements
IO.x[j] = CubicInterp(env.rhomolar_vap, env.x[j], i, i-1, i-2, i-3, IO.rhomolar_vap);
}
}
IO.x[IO.x.size()-1] = 1 - std::accumulate(IO.x.begin(), IO.x.end()-1, 0.0);
try{
NR.call(HEOS, IO.y, IO.x, IO);
env.insert_variables(IO.T, IO.p, IO.rhomolar_liq, IO.rhomolar_vap, IO.hmolar_liq,
IO.hmolar_vap, IO.smolar_liq, IO.smolar_vap, IO.x, IO.y, i+1);
std::cout << "dv " << IO.rhomolar_vap << " dl " << IO.rhomolar_liq << " T " << IO.T << " p " << IO.p << " hl " << IO.hmolar_liq << " hv " << IO.hmolar_vap << " sl " << IO.smolar_liq << " sv " << IO.smolar_vap << " x " << vec_to_string(IO.x, "%0.10Lg") << " Ns " << IO.Nsteps << std::endl;
}
catch(std::exception &e){
continue;
}
i++;
}
}
while (i < env.T.size()-1);
}
void PhaseEnvelopeRoutines::finalize(HelmholtzEOSMixtureBackend &HEOS)
{
enum maxima_points {PMAX_SAT = 0, TMAX_SAT = 1};
@@ -354,7 +413,6 @@ std::vector<std::pair<std::size_t, std::size_t> > PhaseEnvelopeRoutines::find_in
}
if (matched){
std::cout << i << " " << i+1 << std::endl;
intersections.push_back(std::pair<std::size_t, std::size_t>(i, i+1));
}
}

12
src/Backends/Helmholtz/PhaseEnvelopeRoutines.h
View File

@@ -10,18 +10,18 @@ class PhaseEnvelopeRoutines{
*/
static void build(HelmholtzEOSMixtureBackend &HEOS);
/** \brief Refine the phase envelope, adding points in places that are sparse
*
* @param HEOS The HelmholtzEOSMixtureBackend instance to be used
*/
static void refine(HelmholtzEOSMixtureBackend &HEOS);
/** \brief Finalize the phase envelope and calculate maxima values, critical point, etc.
*
* @param HEOS The HelmholtzEOSMixtureBackend instance to be used
*/
static void finalize(HelmholtzEOSMixtureBackend &HEOS);
/** \brief Refine the phase envelope, adding points in places that are sparse
*
* @param HEOS The HelmholtzEOSMixtureBackend instance to be used
*/
//static void refine(HelmholtzEOSMixtureBackend &HEOS);
/** \brief Determine which indices bound a given value
*
* If you provide pressure for instance, it will return each of the indices

14
src/Backends/Helmholtz/VLERoutines.h
View File

@@ -347,7 +347,7 @@ namespace SaturationSolvers
rhomolar_liq = _HUGE; rhomolar_vap = _HUGE; T = _HUGE; p = _HUGE;
};
/** Call the Newton-Raphson VLE Solver
/** \brief Call the Newton-Raphson VLE Solver
*
* This solver must be passed reasonable guess values for the mole fractions,
* densities, etc. You may want to take a few steps of successive substitution
@@ -360,15 +360,15 @@ namespace SaturationSolvers
*/
void call(HelmholtzEOSMixtureBackend &HEOS, const std::vector<long double> &z, std::vector<long double> &z_incipient, newton_raphson_saturation_options &IO);
/*! Build the arrays for the Newton-Raphson solve
This method builds the Jacobian matrix, the sensitivity matrix, etc.
/** \brief Build the arrays for the Newton-Raphson solve
*
*/
* This method builds the Jacobian matrix, the sensitivity matrix, etc.
*
*/
void build_arrays();
/** Check the derivatives in the Jacobian using numerical derivatives.
*/
/** \brief Check the derivatives in the Jacobian using numerical derivatives.
*/
void check_Jacobian();
};
};