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Merged
prehner merged 1 commit into from
Jul 7, 2023
Merged

Fixes for the bubble and dew point calculations #166

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20 changes: 12 additions & 8 deletions feos-core/CHANGELOG.md
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Expand Up @@ -7,22 +7,26 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
## Unreleased
### Added
- Added `Components`, `Residual`, `IdealGas` and `DeBroglieWavelength` traits to decouple ideal gas models from residual models. [#158](https://github.com/feos-org/feos/pull/158)
- Added `JobackParameters` struct that implements `Parameters` including Python bindings. [#158](https://github.com/feos-org/feos/pull/)
- Added `JobackParameters` struct that implements `Parameters` including Python bindings. [#158](https://github.com/feos-org/feos/pull/158)

### Changed
- Changed `EquationOfState` from a trait to a `struct` that is generic over `Residual` and `IdealGas` and implements all necessary traits to be used as equation of state including the ideal gas contribution. [#158](https://github.com/feos-org/feos/pull/)
- The `Parameter` trait no longer has an associated type `IdealGas`. [#158](https://github.com/feos-org/feos/pull/)
- Split properties of `State` into those that require the `Residual` trait (`residual_properties.rs`) and those that require both `Residual + IdealGas` (`properties.rs`). [#158](https://github.com/feos-org/feos/pull/)
- Changed `EquationOfState` from a trait to a `struct` that is generic over `Residual` and `IdealGas` and implements all necessary traits to be used as equation of state including the ideal gas contribution. [#158](https://github.com/feos-org/feos/pull/158)
- The `Parameter` trait no longer has an associated type `IdealGas`. [#158](https://github.com/feos-org/feos/pull/158)
- Split properties of `State` into those that require the `Residual` trait (`residual_properties.rs`) and those that require both `Residual + IdealGas` (`properties.rs`). [#158](https://github.com/feos-org/feos/pull/158)
- State creation routines are split into those that can be used with `Residual` and those that require `Residual + IdealGas`. [#158](https://github.com/feos-org/feos/pull/158)
- `Contributions` enum no longer includes the `ResidualNpt` variant. `ResidualNvt` variant is renamed to `Residual`. [#158](https://github.com/feos-org/feos/pull/158)
- Moved `Verbosity` and `SolverOption` from `phase_equilibria` module to `lib.rs`. [#158](https://github.com/feos-org/feos/pull/)
- Moved `Verbosity` and `SolverOption` from `phase_equilibria` module to `lib.rs`. [#158](https://github.com/feos-org/feos/pull/158)
- Moved `StateVec` into own file and module. [#158](https://github.com/feos-org/feos/pull/158)
- Ideal gas and residual Helmholtz energy models can now be separately implemented in Python via the `PyIdealGas` and `PyResidual` structs. [#158](https://github.com/feos-org/feos/pull/)
- Ideal gas and residual Helmholtz energy models can now be separately implemented in Python via the `PyIdealGas` and `PyResidual` structs. [#158](https://github.com/feos-org/feos/pull/158)
- Bubble and dew point iterations will not attempt a second iteration if no solution is found for the given initial pressure. [#166](https://github.com/feos-org/feos/pull/166)

### Removed
- Removed `EquationOfState` trait. [#158](https://github.com/feos-org/feos/pull/158)
- Removed ideal gas dependencies from `PureRecord` and `SegmentRecord`. [#158](https://github.com/feos-org/feos/pull/)
- Removed Python getter and setter functions and optional arguments for ideal gas records in macros. [#158](https://github.com/feos-org/feos/pull/)
- Removed ideal gas dependencies from `PureRecord` and `SegmentRecord`. [#158](https://github.com/feos-org/feos/pull/158)
- Removed Python getter and setter functions and optional arguments for ideal gas records in macros. [#158](https://github.com/feos-org/feos/pull/158)

### Fixed
- The vapor and liquid states in a bubble or dew point iteration are assigned correctly according to the inputs, rather than based on the mole density which can be incorrect for mixtures with large differences in molar weights. [#166](https://github.com/feos-org/feos/pull/166)

### Packaging
- Updated `num-dual` dependency to 0.7. [#137](https://github.com/feos-org/feos/pull/137)
Expand Down
60 changes: 29 additions & 31 deletions feos-core/src/phase_equilibria/bubble_dew.rs
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Expand Up @@ -119,51 +119,44 @@ impl<E: Residual> PhaseEquilibrium<E, 2> {
match tp_spec {
TPSpec::Temperature(t) => {
// First use given initial pressure if applicable
let mut vle = tp_init
.map(|p| {
if let Some(p) = tp_init {
return Self::iterate_bubble_dew(
eos,
tp_spec,
p,
molefracs_spec,
molefracs_init,
bubble,
options,
);
}

// Next try to initialize with an ideal gas assumption
let vle = Self::starting_pressure_ideal_gas(eos, t, molefracs_spec, bubble)
.and_then(|(p, x)| {
Self::iterate_bubble_dew(
eos,
tp_spec,
p,
molefracs_spec,
molefracs_init,
molefracs_init.or(Some(&x)),
bubble,
options,
)
})
.and_then(Result::ok);
});

// Next try to initialize with an ideal gas assumption
vle = vle.or_else(|| {
let (p, x) =
Self::starting_pressure_ideal_gas(eos, t, molefracs_spec, bubble).ok()?;
// Finally use the spinodal to initialize the calculation
vle.or_else(|_| {
Self::iterate_bubble_dew(
eos,
tp_spec,
p,
Self::starting_pressure_spinodal(eos, t, molefracs_spec)?,
molefracs_spec,
molefracs_init.or(Some(&x)),
molefracs_init,
bubble,
options,
)
.ok()
});

// Finally use the spinodal to initialize the calculation
vle.map_or_else(
|| {
Self::iterate_bubble_dew(
eos,
tp_spec,
Self::starting_pressure_spinodal(eos, t, molefracs_spec)?,
molefracs_spec,
molefracs_init,
bubble,
options,
)
},
Ok,
)
})
}
TPSpec::Pressure(_) => {
let temperature = tp_init.expect("An initial temperature is required for the calculation of bubble/dew points at given pressure!");
Expand Down Expand Up @@ -198,7 +191,7 @@ impl<E: Residual> PhaseEquilibrium<E, 2> {
} else {
starting_x2_dew(eos, t, p, molefracs_spec, molefracs_init)
}?;
bubble_dew(tp_spec, var, state1, state2, options)
bubble_dew(tp_spec, var, state1, state2, bubble, options)
}

fn starting_pressure_ideal_gas(
Expand Down Expand Up @@ -358,6 +351,7 @@ fn bubble_dew<E: Residual>(
mut var_tp: TPSpec,
mut state1: State<E>,
mut state2: State<E>,
bubble: bool,
options: (SolverOptions, SolverOptions),
) -> EosResult<PhaseEquilibrium<E, 2>>
where
Expand Down Expand Up @@ -434,7 +428,11 @@ where
"Bubble/dew point: calculation converged in {} step(s)\n",
k_out
);
Ok(PhaseEquilibrium::from_states(state1, state2))
if bubble {
Ok(PhaseEquilibrium([state2, state1]))
} else {
Ok(PhaseEquilibrium([state1, state2]))
}
} else {
// not converged, return EosError
Err(EosError::NotConverged(String::from("bubble-dew-iteration")))
Expand Down