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Merged
prehner merged 2 commits into from
Feb 14, 2026
Merged

More rigorous treatment of extensive states #330

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33ececb
More rigorous treatment of extensive states
prehner Jan 27, 2026
6577305
include phase fraction in PhaseEquilibrium
prehner Jan 27, 2026
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50 changes: 22 additions & 28 deletions crates/feos-core/src/ad/mod.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
use crate::DensityInitialization::Liquid;
use crate::density_iteration::density_iteration;
use crate::{FeosResult, PhaseEquilibrium, ReferenceSystem, Residual};
use crate::{Composition, FeosResult, PhaseEquilibrium, ReferenceSystem, Residual};
use nalgebra::{Const, SVector, U1, U2};
#[cfg(feature = "rayon")]
use ndarray::{Array1, Array2, ArrayView2, Zip};
Expand Down Expand Up @@ -57,8 +57,8 @@ pub trait PropertiesAD {
let v2 = Gradient::from(v2);
let x = Self::pure_molefracs();

let a1 = self.residual_molar_helmholtz_energy(t, v1, &x);
let a2 = self.residual_molar_helmholtz_energy(t, v2, &x);
let a1 = self.residual_helmholtz_energy(t, v1, &x);
let a2 = self.residual_helmholtz_energy(t, v2, &x);
(a1, a2)
};

Expand Down Expand Up @@ -93,7 +93,7 @@ pub trait PropertiesAD {
let residual_entropy = |v| {
let (a, s) = first_derivative(
partial2(
|t, &v, x| self.lift().residual_molar_helmholtz_energy(t, v, x),
|t, &v, x| self.lift().residual_helmholtz_energy(t, v, x),
&v,
&x,
),
Expand Down Expand Up @@ -215,20 +215,21 @@ pub trait PropertiesAD {
)
}

fn bubble_point_pressure<const P: usize>(
fn bubble_point_pressure<const P: usize, X: Composition<f64, U2>>(
&self,
temperature: Temperature,
pressure: Option<Pressure>,
liquid_molefracs: SVector<f64, 2>,
liquid_molefracs: X,
) -> FeosResult<Pressure<Gradient<P>>>
where
Self: Residual<U2, Gradient<P>>,
{
let eos_f64 = self.re();
let (liquid_molefracs, _) = liquid_molefracs.into_molefracs(&eos_f64)?;
let vle = PhaseEquilibrium::bubble_point(
&eos_f64,
temperature,
&liquid_molefracs,
liquid_molefracs,
pressure,
None,
Default::default(),
Expand All @@ -248,37 +249,38 @@ pub trait PropertiesAD {
let y = y.map(Gradient::from);
let x = liquid_molefracs.map(Gradient::from);

let a_v = self.residual_molar_helmholtz_energy(t, v_v, &y);
let a_v = self.residual_helmholtz_energy(t, v_v, &y);
let (p_l, mu_res_l, dp_l, dmu_l) = self.dmu_dv(t, v_l, &x);
let vi_l = dmu_l / dp_l;
let v_l = vi_l.dot(&y);
let a_l = (mu_res_l - vi_l * p_l).dot(&y);
(a_l, a_v, v_l, v_v)
};
let rho_l = vle.liquid().partial_density.to_reduced();
let rho_l = vle.liquid().partial_density().to_reduced();
let rho_l = [rho_l[0], rho_l[1]];
let rho_v = vle.vapor().partial_density.to_reduced();
let rho_v = vle.vapor().partial_density().to_reduced();
let rho_v = [rho_v[0], rho_v[1]];
let p = -(a_v - a_l
+ t * (y[0] * (rho_v[0] / rho_l[0]).ln() + y[1] * (rho_v[1] / rho_l[1]).ln() - 1.0))
/ (v_v - v_l);
Ok(Pressure::from_reduced(p))
}

fn dew_point_pressure<const P: usize>(
fn dew_point_pressure<const P: usize, X: Composition<f64, U2>>(
&self,
temperature: Temperature,
pressure: Option<Pressure>,
vapor_molefracs: SVector<f64, 2>,
vapor_molefracs: X,
) -> FeosResult<Pressure<Gradient<P>>>
where
Self: Residual<U2, Gradient<P>>,
{
let eos_f64 = self.re();
let (vapor_molefracs, _) = vapor_molefracs.into_molefracs(&eos_f64)?;
let vle = PhaseEquilibrium::dew_point(
&eos_f64,
temperature,
&vapor_molefracs,
vapor_molefracs,
pressure,
None,
Default::default(),
Expand All @@ -298,16 +300,16 @@ pub trait PropertiesAD {
let x = x.map(Gradient::from);
let y = vapor_molefracs.map(Gradient::from);

let a_l = self.residual_molar_helmholtz_energy(t, v_l, &x);
let a_l = self.residual_helmholtz_energy(t, v_l, &x);
let (p_v, mu_res_v, dp_v, dmu_v) = self.dmu_dv(t, v_v, &y);
let vi_v = dmu_v / dp_v;
let v_v = vi_v.dot(&x);
let a_v = (mu_res_v - vi_v * p_v).dot(&x);
(a_l, a_v, v_l, v_v)
};
let rho_l = vle.liquid().partial_density.to_reduced();
let rho_l = vle.liquid().partial_density().to_reduced();
let rho_l = [rho_l[0], rho_l[1]];
let rho_v = vle.vapor().partial_density.to_reduced();
let rho_v = vle.vapor().partial_density().to_reduced();
let rho_v = [rho_v[0], rho_v[1]];
let p = -(a_l - a_v
+ t * (x[0] * (rho_l[0] / rho_v[0]).ln() + x[1] * (rho_l[1] / rho_v[1]).ln() - 1.0))
Expand All @@ -329,12 +331,8 @@ pub trait PropertiesAD {
parameters,
input,
|eos: &Self::Lifted<Gradient<P>>, inp| {
eos.bubble_point_pressure(
inp[0] * KELVIN,
Some(inp[2] * PASCAL),
SVector::from([inp[1], 1.0 - inp[1]]),
)
.map(|p| p.convert_into(PASCAL))
eos.bubble_point_pressure(inp[0] * KELVIN, Some(inp[2] * PASCAL), inp[1])
.map(|p| p.convert_into(PASCAL))
},
)
}
Expand All @@ -353,12 +351,8 @@ pub trait PropertiesAD {
parameters,
input,
|eos: &Self::Lifted<Gradient<P>>, inp| {
eos.dew_point_pressure(
inp[0] * KELVIN,
Some(inp[2] * PASCAL),
SVector::from([inp[1], 1.0 - inp[1]]),
)
.map(|p| p.convert_into(PASCAL))
eos.dew_point_pressure(inp[0] * KELVIN, Some(inp[2] * PASCAL), inp[1])
.map(|p| p.convert_into(PASCAL))
},
)
}
Expand Down
2 changes: 1 addition & 1 deletion crates/feos-core/src/cubic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -221,7 +221,7 @@ mod tests {
let parameters = PengRobinsonParameters::new_pure(propane)?;
let pr = PengRobinson::new(parameters);
let options = SolverOptions::new().verbosity(Verbosity::Iter);
let cp = State::critical_point(&&pr, None, None, None, options)?;
let cp = State::critical_point(&&pr, (), None, None, options)?;
println!("{} {}", cp.temperature, cp.pressure(Contributions::Total));
assert_relative_eq!(cp.temperature, tc * KELVIN, max_relative = 1e-4);
assert_relative_eq!(
Expand Down
2 changes: 1 addition & 1 deletion crates/feos-core/src/density_iteration.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,7 +87,7 @@ where
let (a_res, da_res) = first_derivative(
|molar_volume| {
eos.lift()
.residual_molar_helmholtz_energy(t, molar_volume, &x)
.residual_helmholtz_energy(t, molar_volume, &x)
},
molar_volume,
);
Expand Down
17 changes: 9 additions & 8 deletions crates/feos-core/src/equation_of_state/mod.rs
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
use crate::{ReferenceSystem, StateHD};
use crate::ReferenceSystem;
use crate::state::StateHD;
use nalgebra::{
Const, DVector, DefaultAllocator, Dim, Dyn, OVector, SVector, U1, allocator::Allocator,
};
use num_dual::DualNum;
use quantity::{Energy, MolarEnergy, Moles, Temperature, Volume};
use quantity::{Dimensionless, MolarEnergy, MolarVolume, Temperature};
use std::ops::Deref;

mod residual;
Expand Down Expand Up @@ -164,17 +165,17 @@ where
fn ideal_gas_helmholtz_energy<D2: DualNum<f64, Inner = D> + Copy>(
&self,
temperature: Temperature<D2>,
volume: Volume<D2>,
moles: &Moles<OVector<D2, N>>,
) -> Energy<D2> {
volume: MolarVolume<D2>,
moles: &OVector<D2, N>,
) -> MolarEnergy<D2> {
let total_moles = moles.sum();
let molefracs = moles / total_moles;
let molar_volume = volume / total_moles;
let molar_volume = volume.into_reduced() / total_moles;
MolarEnergy::from_reduced(self.ideal_gas_molar_helmholtz_energy(
temperature.into_reduced(),
molar_volume.into_reduced(),
molar_volume,
&molefracs,
)) * total_moles
)) * Dimensionless::new(total_moles)
}
}

Expand Down
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