Flash Calculations (thermo.flash)¶

This module contains classes and functions for performing flash calculations.

For reporting bugs, adding feature requests, or submitting pull requests, please use the GitHub issue tracker.

Main Interfaces
Specific Flash Algorithms

Main Interfaces ¶

Pure Components ¶

class thermo.flash.FlashPureVLS(constants, correlations, gas, liquids, solids, settings=<thermo.bulk.BulkSettings object>)[source]¶

Bases: thermo.flash.flash_base.Flash

Class for performing flash calculations on pure-component systems. This class is subtantially more robust than using multicomponent algorithms on pure species. It is also faster. All parameters are also attributes.

The minimum information that is needed in addition to the Phase objects is:

MW
Vapor pressure curve if including liquids
Sublimation pressure curve if including solids
Functioning enthalpy models for each phase

Parameters

constantsChemicalConstantsPackage object: Package of chemical constants; these are used as boundaries at times, initial guesses other times, and in all cases these properties are accessible as attributes of the resulting EquilibriumState object, [-]
correlationsPropertyCorrelationsPackage: Package of chemical T-dependent properties; these are used as boundaries at times, for initial guesses other times, and in all cases these properties are accessible as attributes of the resulting EquilibriumState object, [-]
gasPhase object: A single phase which can represent the gas phase, [-]
liquidslist[Phase]: A list of phases for representing the liquid phase; normally only one liquid phase is present for a pure-component system, but multiple liquids are allowed for the really weird cases like having both parahydrogen and orthohydrogen. The liquid phase which calculates a lower Gibbs free energy is always used. [-]
solidslist[Phase]: A list of phases for representing the solid phase; it is very common for multiple solid forms of a compound to exist. For water ice, the list is very long - normally ice is in phase Ih but other phases are Ic, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, XV, XVI, Square ice, and Amorphous ice. It is less common for there to be published, reliable, thermodynamic models for these different phases; for water there is the IAPWS-06 model for Ih, and another model here for phases Ih, Ic, II, III, IV, V, VI, IX, XI, XII. [-]
settingsBulkSettings object: Object containing settings for calculating bulk and transport properties, [-]

Notes

The algorithms in this object are mostly from [1] and [2]. They all boil down to newton methods with analytical derivatives. The phase with the lowest Gibbs energy is the most stable if there are multiple solutions.

Phase input combinations which have specific simplifying assumptions (and thus more speed) are:

a CEOSLiquid and a CEOSGas with the same (consistent) parameters
a CEOSGas with the IGMIX eos and a GibbsExcessLiquid
a IAPWS95Liquid and a IAPWS95Gas
a CoolPropLiquid and a CoolPropGas

Additional information that can be provided in the ChemicalConstantsPackage object and PropertyCorrelationsPackage object that may help convergence is:

Tc, Pc, omega, Tb, and atoms
Gas heat capacity correlations
Liquid molar volume correlations
Heat of vaporization correlations

References

1: Poling, Bruce E., John M. Prausnitz, and John P. O’Connell. The Properties of Gases and Liquids. 5th edition. New York: McGraw-Hill Professional, 2000.
2: Gmehling, Jürgen, Michael Kleiber, Bärbel Kolbe, and Jürgen Rarey. Chemical Thermodynamics for Process Simulation. John Wiley & Sons, 2019.

Examples

Create all the necessary objects using all of the default parameters for decane and do a flash at 300 K and 1 bar:

>>> from thermo import ChemicalConstantsPackage, PRMIX, CEOSLiquid, CEOSGas, FlashPureVLS
>>> constants, correlations = ChemicalConstantsPackage.from_IDs(['decane'])
>>> eos_kwargs = dict(Tcs=constants.Tcs, Pcs=constants.Pcs, omegas=constants.omegas)
>>> liquid = CEOSLiquid(PRMIX, HeatCapacityGases=correlations.HeatCapacityGases, eos_kwargs=eos_kwargs)
>>> gas = CEOSGas(PRMIX, HeatCapacityGases=correlations.HeatCapacityGases, eos_kwargs=eos_kwargs)
>>> flasher = FlashPureVLS(constants, correlations, gas=gas, liquids=[liquid], solids=[])
>>> print(flasher.flash(T=300, P=1e5))
<EquilibriumState, T=300.0000, P=100000.0000, zs=[1.0], betas=[1.0], phases=[<CEOSLiquid, T=300 K, P=100000 Pa>]>

Working with steam:

>>> from thermo import FlashPureVLS, IAPWS95Liquid, IAPWS95Gas, iapws_constants, iapws_correlations
>>> liquid = IAPWS95Liquid(T=300, P=1e5, zs=[1])
>>> gas = IAPWS95Gas(T=300, P=1e5, zs=[1])
>>> flasher = FlashPureVLS(iapws_constants, iapws_correlations, gas, [liquid], [])
>>> PT = flasher.flash(T=800.0, P=1e7)
>>> PT.rho_mass()
29.1071839176
>>> print(flasher.flash(T=600, VF=.5))
<EquilibriumState, T=600.0000, P=12344824.3572, zs=[1.0], betas=[0.5, 0.5], phases=[<IAPWS95Gas, T=600 K, P=1.23448e+07 Pa>, <IAPWS95Liquid, T=600 K, P=1.23448e+07 Pa>]>
>>> print(flasher.flash(T=600.0, H=50802))
<EquilibriumState, T=600.0000, P=10000469.1288, zs=[1.0], betas=[1.0], phases=[<IAPWS95Gas, T=600 K, P=1.00005e+07 Pa>]>
>>> print(flasher.flash(P=1e7, S=104.))
<EquilibriumState, T=599.6790, P=10000000.0000, zs=[1.0], betas=[1.0], phases=[<IAPWS95Gas, T=599.679 K, P=1e+07 Pa>]>
>>> print(flasher.flash(V=.00061, U=55850))
<EquilibriumState, T=800.5922, P=10144789.0899, zs=[1.0], betas=[1.0], phases=[<IAPWS95Gas, T=800.592 K, P=1.01448e+07 Pa>]>

Attributes

VL_IG_hackbool: Whether or not to trust the saturation curve of the liquid phase; applied automatically to the GibbsExcessLiquid phase if there is a single liquid only, [-]
VL_EOS_hacksbool: Whether or not to trust the saturation curve of the EOS liquid phase; applied automatically to the CEOSLiquid phase if there is a single liquid only, [-]
TPV_HSGUA_guess_maxiterint: Maximum number of iterations to try when converging a shortcut model for flashes with one (T, P, V) spec and one (H, S, G, U, A) spec, [-]
TPV_HSGUA_guess_xtolfloat: Convergence tolerance in the iteration variable when converging a shortcut model for flashes with one (T, P, V) spec and one (H, S, G, U, A) spec, [-]
TPV_HSGUA_maxiterint: Maximum number of iterations to try when converging a flashes with one (T, P, V) spec and one (H, S, G, U, A) spec; this is on a per-phase basis, so if there is a liquid and a gas phase, the maximum number of iterations that could end up being tried would be twice this, [-]
TPV_HSGUA_xtolfloat: Convergence tolerance in the iteration variable dimension when converging a flash with one (T, P, V) spec and one (H, S, G, U, A) spec, [-]
TVF_maxiterint: Maximum number of iterations to try when converging a flashes with a temperature and vapor fraction specification, [-]
TVF_xtolfloat: Convergence tolerance in the temperature dimension when converging a flashes with a temperature and vapor fraction specification, [-]
PVF_maxiterint: Maximum number of iterations to try when converging a flashes with a pressure and vapor fraction specification, [-]
PVF_xtolfloat: Convergence tolerance in the pressure dimension when converging a flashes with a pressure and vapor fraction specification, [-]
TSF_maxiterint: Maximum number of iterations to try when converging a flashes with a temperature and solid fraction specification, [-]
TSF_xtolfloat: Convergence tolerance in the temperature dimension when converging a flashes with a temperature and solid fraction specification, [-]
PSF_maxiterint: Maximum number of iterations to try when converging a flashes with a pressure and solid fraction specification, [-]
PSF_xtolfloat: Convergence tolerance in the pressure dimension when converging a flashes with a pressure and solid fraction specification, [-]

Vapor-Liquid Systems ¶

class thermo.flash.FlashVL(constants, correlations, gas, liquid, settings=<thermo.bulk.BulkSettings object>)[source]¶

Bases: thermo.flash.flash_base.Flash

Class for performing flash calculations on one and two phase vapor and liquid multicomponent systems. Use FlashVLN for systems which can have multiple liquid phases.

The minimum information that is needed in addition to the Phase objects is:

MWs
Vapor pressure curve
Functioning enthalpy models for each phase

Parameters

constantsChemicalConstantsPackage object: Package of chemical constants; these are used as boundaries at times, initial guesses other times, and in all cases these properties are accessible as attributes of the resulting EquilibriumState object, [-]
correlationsPropertyCorrelationsPackage: Package of chemical T-dependent properties; these are used as boundaries at times, for initial guesses other times, and in all cases these properties are accessible as attributes of the resulting EquilibriumState object, [-]
gasPhase object: A single phase which can represent the gas phase, [-]
liquidPhase: A single phase which can represent the liquid phase, [-]
settingsBulkSettings object: Object containing settings for calculating bulk and transport properties, [-]

Notes

The algorithms in this object are mostly from [1], [2] and [3]. Sequential substitution without acceleration is used by default to converge two-phase systems.

Quasi-newton methods are used by default to converge bubble and dew point calculations.

Flashes with one (T, P, V) spec and one (H, S, G, U, A) spec are solved by a 1D search over PT flashes.

Additional information that can be provided in the ChemicalConstantsPackage object and PropertyCorrelationsPackage object that may help convergence is:

Tc, Pc, omega, Tb, and atoms
Gas heat capacity correlations
Liquid molar volume correlations
Heat of vaporization correlations

Warning

If this flasher is used on systems that can form two or more liquid phases, and the flash specs are in that region, there is no guarantee which solution is returned. Sometimes it is almost random, jumping back and forth and providing nasty discontinuities.

References

1: Michelsen, Michael L., and Jørgen M. Mollerup. Thermodynamic Models: Fundamentals & Computational Aspects. Tie-Line Publications, 2007.
2: Poling, Bruce E., John M. Prausnitz, and John P. O’Connell. The Properties of Gases and Liquids. 5th edition. New York: McGraw-Hill Professional, 2000.
3: Gmehling, Jürgen, Michael Kleiber, Bärbel Kolbe, and Jürgen Rarey. Chemical Thermodynamics for Process Simulation. John Wiley & Sons, 2019.

Examples

For the system methane-ethane-nitrogen with a composition [0.965, 0.018, 0.017], calculate the vapor fraction of the system and equilibrium phase compositions at 110 K and 1 bar. Use the Peng-Robinson equation of state and the chemsep sample interaction parameter database.

>>> from thermo import ChemicalConstantsPackage, CEOSGas, CEOSLiquid, PRMIX, FlashVL
>>> from thermo.interaction_parameters import IPDB
>>> constants, properties = ChemicalConstantsPackage.from_IDs(['methane', 'ethane', 'nitrogen'])
>>> kijs = IPDB.get_ip_asymmetric_matrix('ChemSep PR', constants.CASs, 'kij')
>>> kijs
[[0.0, -0.0059, 0.0289], [-0.0059, 0.0, 0.0533], [0.0289, 0.0533, 0.0]]
>>> eos_kwargs = {'Pcs': constants.Pcs, 'Tcs': constants.Tcs, 'omegas': constants.omegas, 'kijs': kijs}
>>> gas = CEOSGas(PRMIX, eos_kwargs=eos_kwargs, HeatCapacityGases=properties.HeatCapacityGases)
>>> liquid = CEOSLiquid(PRMIX, eos_kwargs=eos_kwargs, HeatCapacityGases=properties.HeatCapacityGases)
>>> flasher = FlashVL(constants, properties, liquid=liquid, gas=gas)
>>> zs = [0.965, 0.018, 0.017]
>>> PT = flasher.flash(T=110.0, P=1e5, zs=zs)
>>> PT.VF, PT.gas.zs, PT.liquid0.zs
(0.10365, [0.881788, 2.6758e-05, 0.11818], [0.97462, 0.02007, 0.005298])

A few more flashes with the same system to showcase the functionality of the flash interface:

>>> flasher.flash(P=1e5, VF=1, zs=zs).T
133.6
>>> flasher.flash(T=133, VF=0, zs=zs).P
518367.4
>>> flasher.flash(P=PT.P, H=PT.H(), zs=zs).T
110.0
>>> flasher.flash(P=PT.P, S=PT.S(), zs=zs).T
110.0
>>> flasher.flash(T=PT.T, H=PT.H(), zs=zs).T
110.0
>>> flasher.flash(T=PT.T, S=PT.S(), zs=zs).T
110.0

Attributes

PT_SS_MAXITERint: Maximum number of sequential substitution iterations to try when converging a two-phase solution, [-]
PT_SS_TOLfloat: Convergence tolerance in sequential substitution [-]
PT_SS_POLISHbool: When set to True, flashes which are very near a vapor fraction of 0 or 1 are converged to a higher tolerance to ensure the solution is correct; without this, a flash might converge to a vapor fraction of -1e-7 and be called single phase, but with this the correct solution may be found to be 1e-8 and will be correctly returned as two phase.[-]
PT_SS_POLISH_VFfloat: What tolerance to a vapor fraction of 0 or 1; this is an absolute vapor fraction value, [-]
PT_SS_POLISH_MAXITERint: Maximum number of sequential substitution iterations to try when converging a two-phase solution that has been detected to be very sensitive, with a vapor fraction near 0 or 1 [-]
PT_SS_POLISH_TOLfloat: Convergence tolerance in sequential substitution when converging a two-phase solution that has been detected to be very sensitive, with a vapor fraction near 0 or 1 [-]
PT_STABILITY_MAXITERint: Maximum number of iterations to try when converging a stability test, [-]
PT_STABILITY_XTOLfloat: Convergence tolerance in the stability test [-]
DEW_BUBBLE_VF_K_COMPOSITION_INDEPENDENT_XTOLfloat: Convergence tolerance in Newton solver for bubble, dew, and vapor fraction spec flashes when both the liquid and gas model’s K values do not dependent on composition, [-]
DEW_BUBBLE_QUASI_NEWTON_XTOLfloat: Convergence tolerance in quasi-Newton bubble and dew point flashes, [-]
DEW_BUBBLE_QUASI_NEWTON_MAXITERint: Maximum number of iterations to use in quasi-Newton bubble and dew point flashes, [-]
DEW_BUBBLE_NEWTON_XTOLfloat: Convergence tolerance in Newton bubble and dew point flashes, [-]
DEW_BUBBLE_NEWTON_MAXITERint: Maximum number of iterations to use in Newton bubble and dew point flashes, [-]
TPV_HSGUA_BISECT_XTOLfloat: Tolerance in the iteration variable when converging a flash with one (T, P, V) spec and one (H, S, G, U, A) spec using a bisection-type solver, [-]
TPV_HSGUA_BISECT_YTOLfloat: Absolute tolerance in the (H, S, G, U, A) spec when converging a flash with one (T, P, V) spec and one (H, S, G, U, A) spec using a bisection-type solver, [-]
TPV_HSGUA_BISECT_YTOL_ONLYbool: When True, the TPV_HSGUA_BISECT_XTOL setting is ignored and the flash is considered converged once TPV_HSGUA_BISECT_YTOL is satisfied, [-]
TPV_HSGUA_NEWTON_XTOLfloat: Tolerance in the iteration variable when converging a flash with one (T, P, V) spec and one (H, S, G, U, A) spec using a full newton solver, [-]
TPV_HSGUA_NEWTON_MAXITERfloat: Maximum number of iterations when converging a flash with one (T, P, V) spec and one (H, S, G, U, A) spec using full newton solver, [-]
TPV_HSGUA_SECANT_MAXITERfloat: Maximum number of iterations when converging a flash with one (T, P, V) spec and one (H, S, G, U, A) spec using a secant solver, [-]
HSGUA_NEWTON_ANALYTICAL_JACbool: Whether or not to calculate the full newton jacobian analytically or numerically; this would need to be set to False if the phase objects used in the flash do not have complete analytical derivatives implemented, [-]

Vapor and Multiple Liquid Systems ¶

class thermo.flash.FlashVLN(constants, correlations, liquids, gas, solids=None, settings=<thermo.bulk.BulkSettings object>)[source]¶

Bases: thermo.flash.flash_vl.FlashVL

Class for performing flash calculations on multiphase vapor-liquid systems. This rigorous class does not make any assumptions and will search for up to the maximum amount of liquid phases specified by the user. Vapor and each liquid phase do not need to use a consistent thermodynamic model.

The minimum information that is needed in addition to the Phase objects is:

MWs
Vapor pressure curve
Functioning enthalpy models for each phase

Parameters

constantsChemicalConstantsPackage object: Package of chemical constants; these are used as boundaries at times, initial guesses other times, and in all cases these properties are accessible as attributes of the resulting EquilibriumState object, [-]
correlationsPropertyCorrelationsPackage: Package of chemical T-dependent properties; these are used as boundaries at times, for initial guesses other times, and in all cases these properties are accessible as attributes of the resulting EquilibriumState object, [-]
gasPhase object: A single phase which can represent the gas phase, [-]
liquidslist[Phase]: A list of phase objects that can represent the liquid phases; if working with a VLL system with a consistent model, specify the same liquid phase twice; the length of this list is the maximum number of liquid phases that will be searched for, [-]
solidslist[Phase]: Not used, [-]
settingsBulkSettings object: Object containing settings for calculating bulk and transport properties, [-]

Notes

The algorithms in this object are mostly from [1], [2] and [3]. Sequential substitution without acceleration is used by default to converge multiphase systems.

Additional information that can be provided in the ChemicalConstantsPackage object and PropertyCorrelationsPackage object that may help convergence is:

Tc, Pc, omega, Tb, and atoms
Gas heat capacity correlations
Liquid molar volume correlations
Heat of vaporization correlations

References

1: Michelsen, Michael L., and Jørgen M. Mollerup. Thermodynamic Models: Fundamentals & Computational Aspects. Tie-Line Publications, 2007.
2: Poling, Bruce E., John M. Prausnitz, and John P. O’Connell. The Properties of Gases and Liquids. 5th edition. New York: McGraw-Hill Professional, 2000.
3: Gmehling, Jürgen, Michael Kleiber, Bärbel Kolbe, and Jürgen Rarey. Chemical Thermodynamics for Process Simulation. John Wiley & Sons, 2019.

Examples

A three-phase flash of butanol, water, and ethanol with the SRK EOS without BIPs:

>>> from thermo import ChemicalConstantsPackage, CEOSGas, CEOSLiquid, SRKMIX, FlashVLN, PropertyCorrelationsPackage, HeatCapacityGas
>>> constants = ChemicalConstantsPackage(Tcs=[563.0, 647.14, 514.0], Pcs=[4414000.0, 22048320.0, 6137000.0], omegas=[0.59, 0.344, 0.635], MWs=[74.1216, 18.01528, 46.06844], CASs=['71-36-3', '7732-18-5', '64-17-5'])
>>> properties = PropertyCorrelationsPackage(constants=constants,
...                                     HeatCapacityGases=[HeatCapacityGas(poly_fit=(50.0, 1000.0, [-3.787200194613107e-20, 1.7692887427654656e-16, -3.445247207129205e-13, 3.612771874320634e-10, -2.1953250181084466e-07, 7.707135849197655e-05, -0.014658388538054169, 1.5642629364740657, -7.614560475001724])),
...                                     HeatCapacityGas(poly_fit=(50.0, 1000.0, [5.543665000518528e-22, -2.403756749600872e-18, 4.2166477594350336e-15, -3.7965208514613565e-12, 1.823547122838406e-09, -4.3747690853614695e-07, 5.437938301211039e-05, -0.003220061088723078, 33.32731489750759])),
...                                     HeatCapacityGas(poly_fit=(50.0, 1000.0, [-1.162767978165682e-20, 5.4975285700787494e-17, -1.0861242757337942e-13, 1.1582703354362728e-10, -7.160627710867427e-08, 2.5392014654765875e-05, -0.004732593693568646, 0.5072291035198603, 20.037826650765965])),], )
>>> eos_kwargs = dict(Tcs=constants.Tcs, Pcs=constants.Pcs, omegas=constants.omegas)
>>> gas = CEOSGas(SRKMIX, eos_kwargs, HeatCapacityGases=properties.HeatCapacityGases)
>>> liq = CEOSLiquid(SRKMIX, eos_kwargs, HeatCapacityGases=properties.HeatCapacityGases)
>>> flashN = FlashVLN(constants, properties, liquids=[liq, liq], gas=gas)
>>> res = flashN.flash(T=361, P=1e5, zs=[.25, 0.7, .05])
>>> res.phase_count
3

Attributes

SS_NP_MAXITERint: Maximum number of sequential substitution iterations to try when converging a three or more phase solution, [-]
SS_NP_TOLfloat: Convergence tolerance in sequential substitution for a three or more phase solution [-]
SS_NP_TRIVIAL_TOLfloat: Tolerance at which to quick a three-phase flash because it is converging to the trivial solution, [-]
SS_STAB_AQUEOUS_CHECKbool: If True, the first three-phase stability check will be on water (if it is present) as it forms a three-phase solution more than any other component, [-]
DOUBLE_CHECK_2Pbool: This parameter should be set to True if any issues in the solution are noticed. It can slow down two-phase solution. It ensures that all potential vapor-liquid and liquid-liquid phase pairs are searched for stability, instead of testing first for a vapor-liquid solution and then moving on to a three phase flash if an instability is detected, [-]

Base Flash Class ¶

class thermo.flash.Flash[source]¶

Bases: object

Base class for performing flash calculations. All Flash objects need to inherit from this, and common methods can be added to it.

Methods

`flash`([zs, T, P, VF, SF, V, H, S, G, U, A, ...])	Method to perform a flash calculation and return the result as an `EquilibriumState` object.
`plot_TP`(zs[, Tmin, Tmax, pts, branches, ...])	Method to create a plot of the phase envelope as can be calculated from a series of temperature & vapor fraction spec flashes.

flash(zs=None, T=None, P=None, VF=None, SF=None, V=None, H=None, S=None, G=None, U=None, A=None, solution=None, hot_start=None, retry=False, dest=None)[source]¶

Method to perform a flash calculation and return the result as an EquilibriumState object. This generic interface allows flashes with any combination of valid specifications; if a flash is unimplemented and error will be raised.

Parameters

zslist[float], optional: Mole fractions of each component, required unless there is only one component, [-]
Tfloat, optional: Temperature, [K]
Pfloat, optional: Pressure, [Pa]
VFfloat, optional: Vapor fraction, [-]
SFfloat, optional: Solid fraction, [-]
Vfloat, optional: Molar volume of the overall bulk, [m^3/mol]
Hfloat, optional: Molar enthalpy of the overall bulk, [J/mol]
Sfloat, optional: Molar entropy of the overall bulk, [J/(mol*K)]
Gfloat, optional: Molar Gibbs free energy of the overall bulk, [J/mol]
Ufloat, optional: Molar internal energy of the overall bulk, [J/mol]
Afloat, optional: Molar Helmholtz energy of the overall bulk, [J/mol]
solutionstr or int, optional: When multiple solutions exist, if more than one is found they will be sorted by T (and then P) increasingly; this number will index into the multiple solution array. Negative indexing is supported. ‘high’ is an alias for 0, and ‘low’ an alias for -1. Setting this parameter may make a flash slower because in some cases more checks are performed. [-]
hot_startEquilibriumState: A previously converged flash or initial guessed state from which the flash can begin; this parameter can save time in some cases, [-]
retrybool: Usually for flashes like UV or PH, there are multiple sets of possible iteration variables. For the UV case, the prefered iteration variable is P, so each iteration a PV solve is done on the phase; but equally the flash can be done iterating on T, where a TV solve is done on the phase each iteration. Depending on the tolerances, the flash type, the thermodynamic consistency of the phase, and other factors, it is possible the flash can fail. If retry is set to True, the alternate variable set will be iterated as a backup if the first flash fails. [-]
destNone or EquilibriumState or EquilibriumStream: What type of object the flash result is set into; leave as None to obtain the normal EquilibriumState results, [-]

Returns

resultsEquilibriumState: Equilibrium object containing the state of the phases after the flash calculation [-]

Notes

Warning

Not all flash specifications have a unique solution. Not all flash specifications will converge, whether from a bad model, bad inputs, or simply a lack of convergence by the implemented algorithms. You are welcome to submit these cases to the author but the library is provided AS IS, with NO SUPPORT.

Warning

Convergence of a flash may be impaired by providing hot_start. If reliability is desired, do not use this parameter.

Warning

The most likely thermodynamic methods to converge are thermodynamically consistent ones. This means e.g. an ideal liquid and an ideal gas; or an equation of state for both phases. Mixing thermodynamic models increases the possibility of multiple solutions, discontinuities, and other not-fun issues for the algorithms.

plot_TP(zs, Tmin=None, Tmax=None, pts=50, branches=None, ignore_errors=True, values=False, show=True, hot=True)[source]¶

Method to create a plot of the phase envelope as can be calculated from a series of temperature & vapor fraction spec flashes. By default vapor fractions of 0 and 1 are plotted; additional vapor fraction specifications can be specified in the branches argument as a list.

Parameters

zslist[float]: Mole fractions of the feed, [-]
Tminfloat, optional: Minimum temperature to begin the plot, [K]
Tmaxfloat, optional: Maximum temperature to end the plot, [K]
ptsint, optional: The number of points to calculated for each vapor fraction value, [-]
brancheslist[float], optional: Extra vapor fraction values to plot, [-]
ignore_errorsbool, optional: Whether to fail on a calculation failure or to ignore the bad point, [-]
valuesbool, optional: If True, the calculated values will be returned instead of plotted, [-]
showbool, optional: If False, the plot will be returned instead of shown, [-]
hotbool, optional: Whether to restart the next flash from the previous flash or not (intended to speed the call when True), [-]

Returns

Tslist[float]: Temperatures, [K]
P_dews, P_bubbles, branch_Ps

Specific Flash Algorithms ¶

It is recommended to use the Flash classes, which are designed to have generic interfaces. The implemented specific flash algorithms may be changed in the future, but reading their source code may be helpful for instructive purposes.

Flash Calculations (thermo.flash)¶

Main Interfaces ¶

Pure Components ¶

Vapor-Liquid Systems ¶

Vapor and Multiple Liquid Systems ¶

Base Flash Class ¶

Specific Flash Algorithms ¶

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Flash Calculations (thermo.flash)¶

Main Interfaces¶

Pure Components¶

Vapor-Liquid Systems¶

Vapor and Multiple Liquid Systems¶

Base Flash Class¶

Specific Flash Algorithms¶

Main Interfaces ¶

Pure Components ¶

Vapor-Liquid Systems ¶

Vapor and Multiple Liquid Systems ¶

Base Flash Class ¶

Specific Flash Algorithms ¶