pytanksim.classes

Contains the various classes making up pytanksim.

Submodules

• pytanksim.classes.basesimclass
• pytanksim.classes.excessisothermclass
• pytanksim.classes.fluidsorbentclasses
• pytanksim.classes.onephasefluidsimclasses
• pytanksim.classes.onephasesorbentsimclasses
• pytanksim.classes.simresultsclass
• pytanksim.classes.storagetankclasses
• pytanksim.classes.twophasefluidsimclasses
• pytanksim.classes.twophasesorbentsimclasses

Classes

ExcessIsotherm	Stores experimental excess isotherm measurement results.
StoredFluid	A class to calculate the properties of the fluid being stored.
SorbentMaterial	Class containing the properties of a sorbent material.
ModelIsotherm	A base class for model isotherm objects.
MDAModel	A class for the Modified Dubinin-Astakhov model for adsorption.
DAModel	A class for the Dubinin-Astakhov model for adsorption in micropores.
StorageTank	Stores the properties of the storage tank.
SorbentTank	Stores properties of a fluid storage tank filled with sorbents.
SimResults	Class for storing the results of dynamic simulations.
SimParams	A class to store simulation parameters.
BoundaryFlux	Stores information of the mass and energy fluxes on the tank boundaries.
BaseSimulation	An abstract base class for dynamic simulations.
OnePhaseSorbentSim	Base class for simulation of sorbent tanks in the one phase region.
OnePhaseSorbentDefault	Simulates sorbent tanks in the one phase region without constraints.
OnePhaseSorbentVenting	Sorbent tank venting at constant pressure in the one phase region.
OnePhaseSorbentCooled	Sorbent tank cooled at constant pressure in the one phase region.
OnePhaseSorbentHeatedDischarge	Sorbent tank heated at constant pressure in the one phase region.
TwoPhaseSorbentSim	Base class for sorbent tanks in the two-phase region.
TwoPhaseSorbentDefault	Simulate sorbent tanks in the two phase region without constraints.
TwoPhaseSorbentVenting	Sorbent tank venting at constant pressure in the two-phase region.
TwoPhaseSorbentCooled	Sorbent tank cooled at constant pressure in the two-phase region.
TwoPhaseSorbentHeatedDischarge	Sorbent tank heated at constant pressure in the two-phase region.
OnePhaseFluidSim	Base class for one phase fluid simulations.
OnePhaseFluidDefault	Class for simulating fluid storage dynamics in the one phase region.
OnePhaseFluidVenting	Simulate the dynamics of a fluid tank venting at constant pressure.
OnePhaseFluidCooled	Simulates a tank being cooled to maintain constant pressure.
OnePhaseFluidHeatedDischarge	Simulates a tank being heated to discharge at a constant pressure.
TwoPhaseFluidSim	Base class for the simulation of fluid tanks in the two-phase region.
TwoPhaseFluidDefault	Simulation of fluid tanks in the two-phase region w/o constraints.
TwoPhaseFluidVenting	Fluid tank venting at constant pressure in the two-phase region.
TwoPhaseFluidCooled	Fluid tank being cooled at constant pressure in the two-phase region.
TwoPhaseFluidHeatedDischarge	Fluid tank being heated at constant pressure in the two-phase region.

Package Contents

class pytanksim.classes.ExcessIsotherm(adsorbate, sorbent, temperature, loading, pressure)

Stores experimental excess isotherm measurement results.

This class can be provided values directly in Python or it can import the values from a csv file.

adsorbate

Name of the adsorbate gas.

Type:

str

sorbent

Name of the sorbent material.

Type:

str

temperature

Temperature (K) at which the isotherm was measured.

Type:

float

loading

A list of excess adsorption values (mol/kg).

Type:

List[float]

pressure

A list of pressures (Pa) corresponding to points at which the excess adsorption values were measured.

Type:

list[float]

Initialize the ExcessIsotherm class.

Parameters:

• adsorbate (str) – Name of the adsorbate gas.

• sorbent (str) – Name of the sorbent material.

• temperature (float) – Temperature (K) at which the isotherm was measured.

• loading (List[float]) – A list of excess adsorption values (mol/kg).

• pressure (list[float]) – A list of pressures (Pa) corresponding to points at which the excess adsorption values were measured.

Raises:

ValueError – If the lengths of the loading and pressure data don’t match.

Returns:

A class which stores experimental excess adsorption data.

Return type:

ExcessIsotherm

classmethod from_csv(filename, adsorbate, sorbent, temperature)

Import loading and pressure data from a csv file.

Parameters:

• filename (str) – Path leading to the file from which the data is to be imported.

• adsorbate (str) – Name of adsorbate gas.

• sorbent (str) – Name of sorbent material.

• temperature (float) – Temperature (K) at which the data was measured.

Returns:

A class which stores experimental excess adsorption data.

Return type:

ExcessIsotherm

class pytanksim.classes.StoredFluid(fluid_name, EOS='HEOS', mole_fractions=None)

A class to calculate the properties of the fluid being stored.

fluid_name

The name of the fluid being stored which corresponds to fluid names in the package CoolProp.

Type:

str

EOS

The name of the equation of state to be used for the calculations of fluid properties by the package CoolProp.

Type:

str

backend

The CoolProp backend used for calculation of fluid properties at various conditions.

Type:

CoolProp.AbstractState

Initialize a StoredFluid object.

Parameters:

• fluid_name (str, optional) – Name of the fluid. Valid fluid names that work with CoolProp can be found here: http://www.coolprop.org/fluid_properties/PurePseudoPure.html

• EOS (str, optional) – Name of the equation of state to be used for calculations. Default is the Helmholtz Equation of State (HEOS).

• mole_fraction (List) – List of mole fractions of components in a mixture.

Returns:

A class to calculate the properties of the fluid being stored.

Return type:

StoredFluid

fluid_property_dict(p, T)

Generate a dictionary of fluid properties using CoolProp.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K)

Returns:

Dictionary containing several fluid properties needed for various calculations in pytanksim.

Return type:

Dict[str, float]

Notes

Below is a list of keys and the variables they contain for the output dictionary.

• hf: enthalpy (J/mol)

• drho_dp: first partial derivative of density (mol/m^3) w.r.t. pressure (Pa)

• drho_dT: first partial derivative of density (mol/m^3) w.r.t. temperature (K)

• rhof: density (mol/m^3)

• dh_dp: first partial derivative of enthalpy (J/mol) w.r.t. pressure (Pa)

• dh_dT: first partial derivative of enthalpy (J/mol) w.r.t. temperature (K)

• uf: internal energy (J/mol)

• du_dp: first partial derivative of internal energy (J/mol) w.r.t. pressure (Pa)

• du_dT: first partial derivative of internal energy (J/mol) w.r.t. temperature (K)

• MW: molar mass (kg/mol)

saturation_property_dict(T, Q=0)

Generate a dictionary of fluid properties at saturation.

Parameters:

• T (float) – Temperature in K.

• Q (float) – Vapor quality of the fluid being stored.

Returns:

A dictionary containing the fluid properties at saturation at a given temperature.

Return type:

Dict[str, float]

Notes

Below is a list of keys and the variables they contain for the output dictionary.

• psat: saturation vapor pressure (Pa)

• dps_dT: first derivative of the saturation vapor pressure (Pa) w.r.t. temperature (K).

• hf: enthalpy (J/mol)

• drho_dp: first partial derivative of density (mol/m^3) w.r.t. pressure (Pa)

• drho_dT: first partial derivative of density (mol/m^3) w.r.t. temperature (K)

• rhof: density (mol/m^3)

• dh_dp: first partial derivative of enthalpy (J/mol) w.r.t. pressure (Pa)

• dh_dT: first partial derivative of enthalpy (J/mol) w.r.t. temperature (K)

• uf: internal energy (J/mol)

• du_dp: first partial derivative of internal energy (J/mol) w.r.t. pressure (Pa)

• du_dT: first partial derivative of internal energy (J/mol) w.r.t. temperature (K)

• MW: molar mass (kg/mol)

determine_phase(p, T)

Determine the phase of the fluid being stored.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

Returns:

String that could either be “Supercritical”, “Gas”, “Liquid”, or “Saturated” depending on the bulk fluid phase.

Return type:

str

class pytanksim.classes.SorbentMaterial(skeletal_density, bulk_density, specific_surface_area, model_isotherm, mass=0, molar_mass=0.01201, Debye_temperature=1500, heat_capacity_function=None)

Class containing the properties of a sorbent material.

mass

Mass of sorbent (kg).

Type:

float

skeletal_density

Skeletal density of the sorbent (kg/m^3).

Type:

float

bulk_density

Tapped/compacted bulk density of the sorbent (kg/m^3).

Type:

float

specific_surface_area

Specific surface area of the sorbent (m^2/g).

Type:

float

model_isotherm

Model of fluid adsorption on the sorbent.

Type:

ModelIsotherm

molar_mass

Molar mass of the sorbent material in kg/mol. The default is 12.01E-3 which corresponds to carbon materials.

Type:

float, optional

Debye_temperature

The Debye temperature (K) determining the specific heat of the sorbent at various temperatures. The default is 1500, the value for carbon.

Type:

float, optional

heat_capacity_function

A function which takes in the temperature (K) of the sorbent and returns its specific heat capacity (J/(kg K)). If specified, this function will override the Debye model for specific heat calculation. The default is None.

Type:

Callable[[float], float], optional

Initialize the SorbentMaterial class.

Parameters:

• skeletal_density (float) – Skeletal density of the sorbent (kg/m^3).

• bulk_density (float) – Tapped/compacted bulk density of the sorbent (kg/m^3).

• specific_surface_area (float) – Specific surface area of the sorbent (m^2/g).

• model_isotherm (ModelIsotherm) – Model of fluid adsorption on the sorbent.

• mass (float, optional) – Mass of sorbent (kg). The default is None.

• molar_mass (float, optional) – Molar mass of the sorbent material. The default is 12.01E-3 which corresponds to carbon materials.

• Debye_temperature (float, optional) – The Debye temperature determining the specific heat of the sorbent at various temperatures. The default is 1500, the value for carbon.

• heat_capacity_function (Callable, optional) – A function which takes in the temperature (K) of the sorbent and returns its specific heat capacity (J/(kg K)). If specified, this function will override the Debye model for specific heat calculation. The default is None.

Returns:

Class containing the properties of a sorbent material.

Return type:

SorbentMaterial

class pytanksim.classes.ModelIsotherm

A base class for model isotherm objects.

Contains methods to calculate various thermodynamic properties of the adsorbed phase.

pressure_from_absolute_adsorption(n_abs, T, p_max_guess=35000000.0)

Calculate a pressure value corresponding to an adsorbed amount.

Parameters:

• n_abs (float) – Amount adsorbed (mol/kg).

• T (float) – Temperature (K).

• p_max_guess (float, optional) – Maximum pressure (Pa) for the optimization. The default is 20E6. If the value provided is larger than the maximum that can be handled by the CoolProp backend, it will take the maximum that can be handled by the CoolProp backend.

Returns:

Pressure (Pa) corresponding to the specified adsorbed amount and temperature value.

Return type:

float

isosteric_enthalpy(p, T, q=1)

Calculate isosteric adsorbed enthalpy (J/mol).

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 to 1. The default is 1.

Returns:

Isosteric enthalpy of adsorption (J/mol).

Return type:

float

isosteric_internal_energy(p, T, q=1)

Calculate the isosteric internal energy of the adsorbed phase.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 to 1. The default is 1.

Returns:

Isosteric internal energy of the adsorbed phase (J/mol).

Return type:

float

_derivfunc(func, var, point, qinit, stepsize)

Calculate the first partial derivative.

It automatically decides the direction of the derivative so that the evaluations are done for fluids at the same phases. Otherwise, there will be discontinuities in the fluid properties at different phases which causes the resulting derivative values to be invalid.

_derivfunc_second(func, point, qinit, stepsize)

Calculate the second partial derivative.

It automatically decides the direction of the derivative so that the evaluations are done for fluids at the same phases. Otherwise, there will be discontinuities in the fluid properties at different phases which causes the resulting derivative values to be invalid.

isosteric_energy_temperature_deriv(p, T, q=1, stepsize=0.001)

Calculate first derivative of isosteric internal energy w.r.t. T.

This function calculates the first partial derivative of the isosteric internal energy of the adsorbed phase (J/mol) w.r.t. temperature (K).

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 to 1. The default is 1.

• stepsize (float, optional) – Stepsize for numerical derivative. The default is 1E-3.

Returns:

The first partial derivative of the isosteric internal energy of the adsorbed phase (J/mol) w.r.t. temperature (K).

Return type:

float

differential_energy(p, T, q=1)

Calculate the differential energy of adsorption (J/mol).

The calculation is based on Myers & Monson [1]_.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 to 1. The default is 1.

Returns:

The differential energy of adsorption (J/mol).

Return type:

float

Notes

[1]

A. L. Myers and P. A. Monson, ‘Physical adsorption of gases: the case for absolute adsorption as the basis for thermodynamic analysis’, Adsorption, vol. 20, no. 4, pp. 591–622, May 2014, doi: 10.1007/s10450-014-9604-1.

differential_heat(p, T, q=1)

Calculate the differential heat of adsorption (J/mol).

The calculation is based on Myers & Monson [1]_.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 to 1. The default is 1.

Returns:

The differential heat of adsorption (J/mol).

Return type:

float

Notes

[1]

A. L. Myers and P. A. Monson, ‘Physical adsorption of gases: the case for absolute adsorption as the basis for thermodynamic analysis’, Adsorption, vol. 20, no. 4, pp. 591–622, May 2014, doi: 10.1007/s10450-014-9604-1.

internal_energy_adsorbed(p, T, q=1)

Calculate the molar integral internal energy of adsorption (J/mol).

The calculation is based on Myers & Monson [1]_.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 to 1. The default is 1.

Returns:

The differential energy of adsorption (J/mol).

Return type:

float

Notes

[1]

A. L. Myers and P. A. Monson, ‘Physical adsorption of gases: the case for absolute adsorption as the basis for thermodynamic analysis’, Adsorption, vol. 20, no. 4, pp. 591–622, May 2014, doi: 10.1007/s10450-014-9604-1.

areal_immersion_energy(T)

Calculate the areal energy of immersion (J/m^2).

The calculation is based on the one written in Rouquerol et al. [1]_.

Parameters:

T (float) – Temperature (K).

Returns:

Areal energy of immersion (J/m^2)

Return type:

float

class pytanksim.classes.MDAModel(sorbent, stored_fluid, nmax, f0, alpha, beta, va, m=2, k=2, va_mode='Constant', f0_mode='Constant')

Bases: ModelIsotherm

A class for the Modified Dubinin-Astakhov model for adsorption.

A key modification compared to the DA model is the use of the enthalpic and entropic factors to calculate the adsorption energy as a function of temperature instead of treating it as a constant.

Initialize the MDAModel class.

Parameters:

• sorbent (str) – Name of the sorbent material.

• stored_fluid (StoredFluid) – Object to calculate the thermophysical properties of the adsorbate.

• nmax (float) – Maximum adsorbed amount (mol/kg) at saturation.

• f0 (float) – Fugacity at saturation (Pa).

• alpha (float) – The empirical enthalpic factor for determining the characteristic energy of adsorption.

• beta (float) – The empirical entropic factor for determining the characteristic energy of adsorption.

• va (float) – The volume of the adsorbed phase (m^3/kg).

• m (float, optional) – The empirical heterogeneity parameter for the Dubinin-Astakhov model. The default is 2.

• k (float, optional) – The empirical heterogeneity parameter for Dubinin’s approximation of the saturation fugacity above critical temperatures. The default is 2.

• va_mode (str, optional) – Determines how the adsorbed phase density is calculated. “Ozawa” uses Ozawa’s approximation to calculate the adsorbed phase density. “Constant” assumes a constant adsorbed phase volume. The default is “Constant”.

• f0_mode (str, optional) – Determines how the fugacity at saturation is calculated. “Dubinin” uses Dubinin’s approximation. “Constant” assumes a constant value for the fugacity at saturation. The default is “Constant”.

Returns:

An MDAModel object. It can calculate the excess and absolute adsorbed amounts at various pressures and temperatures, and it can provide thermophysical properties of the adsorbed phase.

Return type:

MDAModel

dlnf0_dT(T)

Calculate derivative of log saturation fugacity w.r.t. temperature.

Parameters:

T (float) – Temperature (K)

Returns:

Derivative of log saturation fugacity w.r.t. temperature

Return type:

float

f0_fun(T)

Calculate saturation fugacity as a function of temperature.

Parameters:

T (float) – Temperature (K).

Returns:

Saturation fugacity (Pa).

Return type:

float

n_absolute(p, T)

Calculate the absolute adsorbed amount at given conditions.

Parameters:

• p (float) – Pressure (Pa)

• T (float) – Temperature (K)

Returns:

Absolute adsorbed amount (mol/kg).

Return type:

float

v_ads(p, T)

Calculate the adsorbed phase volume at the given condtions.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

Returns:

Adsorbed phase volume (m^3/kg)

Return type:

float

n_excess(p, T, q=1)

Calculate the excess adsorbed amount at the given conditions.

Parameters:

• p (float) – Pressure (Pa)

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 and 1. The default is 1.

Returns:

Excess adsorbed amount (mol/kg).

Return type:

float

internal_energy_adsorbed(p, T, q=1)

Calculate the molar integral internal energy of adsorption (J/mol).

The calculation is based on Myers & Monson [1]_.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 to 1. The default is 1.

Returns:

The molar integral energy of adsorption (J/mol).

Return type:

float

Notes

[1]

A. L. Myers and P. A. Monson, ‘Physical adsorption of gases: the case for absolute adsorption as the basis for thermodynamic analysis’, Adsorption, vol. 20, no. 4, pp. 591–622, May 2014, doi: 10.1007/s10450-014-9604-1.

differential_energy_na(na, T)

Calculate differential energy of adsorption analytically.

Parameters:

• na (float) – Amount adsorbed (mol/kg)

• T (float) – Temperature (K)

Returns:

Differential energy of adsorption (J/mol)

Return type:

float

differential_energy(p, T, q=1)

Calculate differential energy of adsorption analytically.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float) – Vapor quality.

Returns:

Differential energy of adsorption (J/mol).

Return type:

float

classmethod from_ExcessIsotherms(ExcessIsotherms, stored_fluid=None, sorbent=None, nmaxguess=71.6, f0guess=1470000000.0, alphaguess=3080, betaguess=18.9, vaguess=0.00143, mguess=2.0, kguess=2.0, va_mode='Fit', f0_mode='Fit', m_mode='Fit', k_mode='Fit', beta_mode='Fit', pore_volume=0.003, verbose=True)

Fit the MDA model from a list of excess adsorption data.

Parameters:

• ExcessIsotherms (List[ExcessIsotherm]) – A list of ExcessIsotherm objects which contain measurement data at various temperatures.

• stored_fluid (StoredFluid, optional) – Object for calculating the properties of the adsorbate. The default is None. If None, the StoredFluid object inside of one of the ExcessIsotherm objects passed will be used.

• sorbent (str, optional) – Name of sorbent material. The default is None. If None, name will be taken from one of the ExcessIsotherm objects passed.

• nmaxguess (float, optional) – The initial guess for the maximum adsorbed amount (mol/kg). The default is 71.6.

• f0guess (float, optional) – The initial guess for the fugacity at saturation (Pa). The default is 1470E6.

• alphaguess (float, optional) – The initial guess for the enthalpy factor determining the characteristic energy of adsorption. The default is 3080.

• betaguess (float, optional) – The initial guess for the entropy factor determining the characteristic energy of adsorption. The default is 18.9.

• vaguess (float, optional) – Initial guess for the adsorbed phase volume (m^3/kg). The default is 0.00143.

• mguess (float, optional) – The initial guess for the heterogeneity parameter of the Dubinin-Astakhov equation. The default is 2.0.

• kguess (float, optional) – The initial guess for the heterogeneity parameter of Dubinin’s approximation method for saturation fugacity. The default is 2.0.

• va_mode (str, optional) – Determines how the volume of the adsorbed phase (va) is calculated. If “Fit”, va is a constant to be fitted statistically. If “Ozawa”, Ozawa’s approximation is used to calculate va and va is not a fitting parameter. If “Constant”, the user supplied value for vaguess is taken as the volume. The default is “Fit”.

• f0_mode (str, optional) – Determines how the fugacity at saturation (f0) is calculated. If “Fit” then f0 is a constant to be statistically fitted to the data. If “Dubinin” then Dubinin’s approximation is used. If “Constant” then the user supplied value for f0guess is used. The default is “Fit”.

• m_mode (str, optional) – Determines whether the heterogeneity parameter of the Dubinin- Astakhov equation is taken as a user-supplied constant (if “Constant”) or a fitted parameter (if “Fit”). The default is “Fit”.

• k_mode (str, optional) – Determines whether the heterogeneity parameter of Dubinin’s approximation for the fugacity above the critical temperature is taken as a user-supplied constant value (if “Constant”) or as a statistically fitted parameter (if “Fit”). The default is “Fit”.

• beta_mode (str, optional) – Determines whether the entropic factor determining the characteristic energy of adsorption is taken as a user-supplied constant (if “Constant”) or as a fitted parameter (if “Fit”). The default is “Fit”.

• pore_volume (float, optional) – The experimentally measured pore volume of the sorbent material (m^3/kg). It serves as the maximum possible physical value for the parameters w0 and va. The default is 0.003.

• verbose (bool, optional) – Determines whether or not the complete fitting quality report is logged for the user. The default is True.

Returns:

An MDAModel object. It can calculate the excess and absolute adsorbed amounts at various pressures and temperatures, and it can provide thermophysical properties of the adsorbed phase.

Return type:

MDAModel

class pytanksim.classes.DAModel(sorbent, stored_fluid, w0, f0, eps, m=2, k=2, rhoa=None, va=None, va_mode='Constant', rhoa_mode='Constant', f0_mode='Dubinin')

Bases: ModelIsotherm

A class for the Dubinin-Astakhov model for adsorption in micropores.

sorbent

Name of sorbent material.

Type:

str

stored_fluid

Object containing properties of the adsorbate.

Type:

StoredFluid

w0

The volume of the adsorbed phase at saturation (m^3/kg).

Type:

float

f0

The fugacity at adsorption saturation (Pa).

Type:

float

eps

Characteristic energy of adsorption (J/mol).

Type:

float

m

The empirical heterogeneity parameter for the Dubinin-Astakhov model. The default is 2.

Type:

float, optional

k

The empirical heterogeneity parameter for Dubinin’s approximation of the saturation fugacity above critical temperatures. The default is 2.

Type:

float, optional

rhoa

The density of the adsorbed phase (mol/m^3). The default is None. If None, the value will be taken as the liquid density at 1 bar.

Type:

float, optional

va

The volume of the adsorbed phase (m^3/kg). The default is None. If None and va_mode is “Constant”, the va_mode will be switched to “Excess” and the va will be assumed to be 0.

Type:

float, optional

va_mode

Determines how the adsorbed phase volume is calculated. “Excess” assumes that the adsorbed phase volume is 0, so the model calculates excess adsorption instead of absolute adsorption. “Constant” assumes a constant adsorbed phase volume. “Vary” will assume that the adsorbed phase volume varies according to the pore filling mechanism posited by the Dubinin-Astakhov equation. The default is “Constant”, but if the parameter va is not specified it will switch to “Excess”.

Type:

str, optional

rhoa_mode

Determines how the adsorbed phase density is calculated. “Ozawa” uses Ozawa’s approximation to calculate the adsorbed phase density. “Constant” assumes a constant adsorbed phase volume. The default is “Constant”.

Type:

str, optional

f0_mode

Determines how the fugacity at saturation is calculated. “Dubinin” uses Dubinin’s approximation. “Constant” assumes a constant value for the fugacity at saturation. The default is “Dubinin”.

Type:

str, optional

Initialize the DAModel class.

Parameters:

• sorbent (str) – Name of sorbent material.

• stored_fluid (StoredFluid) – Object containing properties of the adsorbate.

• w0 (float) – The volume of the adsorbed phase at saturation (m^3/kg).

• f0 (float) – The fugacity at adsorption saturation (Pa).

• eps (float) – Characteristic energy of adsorption (J/mol).

• m (float, optional) – The empirical heterogeneity parameter for the Dubinin-Astakhov model. The default is 2.

• k (float, optional) – The empirical heterogeneity parameter for Dubinin’s approximation of the saturation fugacity above critical temperatures. The default is 2.

• va (float, optional) – The volume of the adsorbed phase (m^3/kg). The default is None.

• rhoa (float, optional) – The density of the adsorbed phase (mol/m^3). The default is None. If None, the value will be taken as the liquid density at 1 bar.

• va_mode (str, optional) – Determines how the adsorbed phase volume is calculated. “Excess” assumes that the adsorbed phase volume is 0, so the model calculates excess adsorption instead of absolute adsorption. “Constant” assumes a constant adsorbed phase volume. “Vary” will assume that the adsorbed phase volume varies according to the pore filling mechanism posited by the Dubinin-Astakhov equation. The default is “Constant”, but if the parameter va is not specified it will switch to “Excess”.

• rhoa_mode (str, optional) – Determines how the adsorbed phase density is calculated. “Ozawa” uses Ozawa’s approximation to calculate the adsorbed phase density. “Constant” assumes a constant adsorbed phase volume. The default is “Constant”.

• f0_mode (str, optional) – Determines how the fugacity at saturation is calculated. “Dubinin” uses Dubinin’s approximation. “Constant” assumes a constant value for the fugacity at saturation. The default is “Dubinin”.

Returns:

A DAModel object which can calculate excess and absolute adsorption at various conditions as well as the thermophysical properties of the adsorbed phase.

Return type:

DAModel

f0_calc(T)

Calculate the fugacity at saturation (Pa) at a given temperature.

Parameters:

T (float) – Temperature (K).

Returns:

Fugacity at saturation (Pa).

Return type:

float

dlnf0_dT(T)

Calculate derivative of log saturation fugacity w.r.t. temperature.

Parameters:

T (float) – Temperature (K)

Returns:

Derivative of log saturation fugacity w.r.t. temperature

Return type:

float

rhoa_calc(T)

Calculate the density of the adsorbed phase at a given temperature.

Parameters:

T (float) – Temperature (K).

Returns:

The density of the adsorbed phase (mol/m^3).

Return type:

float

v_ads(p, T)

Calculate the volume of the adsorbed phase (m^3/kg).

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

Returns:

Volume of the adsorbed phase (m^3/kg).

Return type:

float

n_absolute(p, T)

Calculate the absolute adsorbed amount at a given condition.

Parameters:

• p (float) – Pressure(Pa).

• T (float) – Temperature(K).

Returns:

Absolute adsorbed amount (mol/kg).

Return type:

float

n_excess(p, T, q=1)

Calculate the excess adsorbed amount at a given condition.

Parameters:

• p (float) – Pressure (Pa)

• T (float) – Temperature (K)

• q (float, optional) – The vapor quality of the bulk adsorbate. Can vary between 0 and 1. The default is 1.

Returns:

Excess adsorbed amount (mol/kg).

Return type:

float

differential_energy_na(na, T)

Calculate differential energy of adsorption analytically.

Parameters:

• na (float) – Amount adsorbed (mol/kg)

• T (float) – Temperature (K)

Returns:

Differential energy of adsorption (J/mol)

Return type:

float

differential_energy(p, T, q)

Calculate differential energy of adsorption analytically.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float) – Vapor quality.

Returns:

Differential energy of adsorption (J/mol).

Return type:

float

internal_energy_adsorbed(p, T, q=1)

Calculate the molar integral internal energy of adsorption (J/mol).

The calculation is based on Myers & Monson [1]_.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the bulk fluid. Can vary between 0 to 1. The default is 1.

Returns:

The differential energy of adsorption (J/mol).

Return type:

float

Notes

[1]

A. L. Myers and P. A. Monson, ‘Physical adsorption of gases: the case for absolute adsorption as the basis for thermodynamic analysis’, Adsorption, vol. 20, no. 4, pp. 591–622, May 2014, doi: 10.1007/s10450-014-9604-1.

classmethod from_ExcessIsotherms(ExcessIsotherms, stored_fluid=None, sorbent=None, w0guess=0.001, f0guess=1470000000.0, epsguess=3000, vaguess=0.001, rhoaguess=None, mguess=2.0, kguess=2.0, rhoa_mode='Fit', f0_mode='Fit', m_mode='Fit', k_mode='Fit', va_mode='Excess', pore_volume=0.003, verbose=True)

Fit the DA model to a list of ExcessIsotherm data.

Parameters:

• ExcessIsotherms (List[ExcessIsotherm]) – A list containing ExcessIsotherm objects which contain measurement data at various temperatures.

• stored_fluid (StoredFluid, optional) – Object for calculating the properties of the adsorbate. The default is None. If None, the StoredFluid object inside of one of the ExcessIsotherm objects passed will be used.

• sorbent (str, optional) – Name of sorbent material. The default is None. If None, name will be taken from one of the ExcessIsotherm objects passed.

• w0guess (float, optional) – The initial guess for the adsorbed phase volume at saturation (m^3/kg). The default is 0.001.

• f0guess (float, optional) – The initial guess for the fugacity at saturation (Pa). The default is 1470E6.

• epsguess (float, optional) – The initial guess for the characteristic energy of adsorption (J/mol). The default is 3000.

• vaguess (float, optional) – The initial guess for the volume of the adsorbed phase (m^3/kg). The default is 0.001.

• rhoaguess (float, optional) – The initial guess for the adsorbed phase density (mol/m^3). The default is None. If None, it will be taken as the liquid density at 1 bar.

• mguess (float, optional) – The initial guess for the heterogeneity parameter of the Dubinin-Astakhov equation. The default is 2.0.

• kguess (float, optional) – The initial guess for the heterogeneity parameter of Dubinin’s approximation method for saturation fugacity. The default is 2.0.

• rhoa_mode (str, optional) – Determines how the density of the adsorbed phase (rhoa) is calculated. If “Fit”, rhoa is a constant to be fitted statistically. If “Ozawa”, Ozawa’s approximation is used to calculate rhoa and rhoa is not a fitting parameter. If “Constant”, the user supplied value for rhoaguess is taken as the density. The default is “Fit”.

• f0_mode (str, optional) – Determines how the fugacity at saturation (f0) is calculated. If “Fit” then f0 is a constant to be statistically fitted to the data. If “Dubinin” then Dubinin’s approximation is used. If “Constant” then the user supplied value for f0guess is used. The default is “Fit”.

• m_mode (str, optional) – Determines whether the heterogeneity parameter of the Dubinin- Astakhov equation is taken as a user-supplied constant (if “Constant”) or a fitted parameter (if “Fit”). The default is “Fit”.

• k_mode (str, optional) – Determines whether the heterogeneity parameter of Dubinin’s approximation for the fugacity above the critical temperature is taken as a user-supplied constant value (if “Constant”) or as a statistically fitted parameter (if “Fit”). The default is “Fit”.

• va_mode (str, optional) – Determines how the volume of the adsorbed phase is calculated. If “Fit”, the value is a statistically fitted constant. If “Constant”, the value is the user defined value vaguess. If “Vary”, the value varies w.r.t. pressure according to the micropore filling mechanism posited by the Dubinin-Astakhov model. The default is “Excess”.

• pore_volume (float, optional) – The experimentally measured pore volume of the sorbent material (m^3/kg). It serves as the maximum possible physical value for the parameters w0 and va. The default is 0.003.

• verbose (bool, optional) – Determines whether or not the complete fitting quality report is logged for the user. The default is True.

Returns:

A DAModel object which can calculate excess and absolute adsorption at various conditions as well as the thermophysical properties of the adsorbed phase.

Return type:

DAModel

class pytanksim.classes.StorageTank(stored_fluid, aluminum_mass=0, carbon_fiber_mass=0, steel_mass=0, vent_pressure=None, min_supply_pressure=100000.0, thermal_resistance=0, surface_area=0, heat_transfer_coefficient=0, volume=None, set_capacity=None, full_pressure=None, empty_pressure=None, full_temperature=None, empty_temperature=None, full_quality=1, empty_quality=1)

Stores the properties of the storage tank.

It also has methods to calculate useful quantities such as tank dormancy given a constant heat leakage rate, the internal energy of the fluid being stored at various conditions, etc.

volume

Internal volume of the storage tank (m^3).

Type:

float

stored_fluid

Object to calculate the thermophysical properties of the fluid being stored.

Type:

StoredFluid

aluminum_mass

The mass of aluminum making up the tank walls (kg). The default is 0.

Type:

float, optional

carbon_fiber_mass

The mass of carbon fiber making up the tank walls (kg). The default is 0.

Type:

float, optional

steel_mass

The mass of steel making up the tank walls (kg). The default is 0.

Type:

float, optional

vent_pressure

The pressure (Pa) at which the fluid being stored must be vented. The default is None. If None, the value will be taken as the maximum value where the CoolProp backend can calculate the properties of the fluid being stored.

Type:

float, optional

min_supply_pressure

The minimum supply pressure (Pa) for discharging simulations.The default is 1E5.

Type:

float, optional

thermal_resistance

The thermal resistance of the tank walls (K/W). The default is 0. If 0, the value will not be considered in simulations.

Type:

Callable, optional

surface_area

The surface area of the tank that is in contact with the environment (m^2). The default is 0.

Type:

float, optional

heat_transfer_coefficient

The heat transfer coefficient of the tank surface (W/(m^2 K)). The default is 0.

Type:

Callable, optional

Initialize a StorageTank object.

Parameters:

• stored_fluid (StoredFluid) – Object to calculate the thermophysical properties of the fluid being stored.

• aluminum_mass (float, optional) – The mass of aluminum making up the tank walls (kg). The default is 0.

• carbon_fiber_mass (float, optional) – The mass of carbon fiber making up the tank walls (kg). The default is 0.

• steel_mass (float, optional) – The mass of steel making up the tank walls (kg). The default is 0.

• vent_pressure (float, optional) – The pressure (Pa) at which the fluid being stored must be vented. The default is None. If None, the value will be taken as the maximum value where the CoolProp backend can calculate the properties of the fluid being stored.

• min_supply_pressure (float, optional) – The minimum supply pressure (Pa) for discharging simulations.The default is 1E5.

• thermal_resistance (Callable or float, optional) –

  A function which returns the thermal resistance of the tank walls (K/W) as a function of tank pressure (Pa), tank temperature (K), time (s), and temperature of surroundings (K). The default is 0. If a float is provided, it will be converted to a function which returns that value everywhere. If both this and the arguments ‘surface_area’ and ‘heat_transfer_coefficient’ are passed, two values of thermal resistance will be calculated and the highest value between the two will be taken at each time step. Thus, to avoid confusion, one should either: (a) use the other two arguments together, or (b) use this one, but not both at the same time.

  If a callable is passed, it must have the signature:

  def tr_function(p, T, time, env_temp):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      # 'env_temp' is the temperature of surroundings (K)
      ....
      # Returned is the thermal resistance (K/W)
      return tr_value
  

• surface_area (float, optional) – The surface area of the tank that is in contact with the environment (m^2). The default is 0.

• heat_transfer_coefficient (Callable or float, optional) –

  A function which returns the heat transfer coefficient of the tank walls (W/(m^2 K)) as a function of tank pressure (Pa), tank temperature (K), time (s), and temperature of surroundings (K). The default is 0. If a float is provided, it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def htc_function(p, T, time, env_temp):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      # 'env_temp' is the temperature of surroundings (K)
      ....
      # Returned is the heat transfer coefficient (W/(m^2 K))
      return heat_transfer_coef
  

• volume (float, optional) – Internal volume of the storage tank (m^3). The default is None. This value is required unless the set capacity and operating conditions are defined, in which case the volume is calculated from the capacity and operating conditions.

• set_capacity (float, optional) – Set internal capacity of the storage tank (mol). The default is None. If specified, this will override the user-specified tank volume.

• full_pressure (float, optional) – Pressure (Pa) of the tank when it is considered full. The default is None.

• empty_pressure (float, optional) – Pressure (Pa) of the tank when it is considered empty. The default is None.

• full_temperature (float, optional) – Temperature (K) of the tank when it is considered full. The default is None.

• empty_temperature (float, optional) – Temperature (K) of the tank when it is considered empty. The default is None.

• full_quality (float, optional) – Vapor quality of the tank when it is considered full. The default is 1 (Gas).

• empty_quality (float, optional) – Vapor quality of the tank when it is considered empty. The default is 1 (Gas).

Raises:

• ValueError – If any of the mass values provided are less than 0.

• ValueError – If the vent pressure set is higher than what can be calculated by ‘CoolProp’.

• ValueError – If neither the volume nor the complete capacity and the pressure and temperature swing conditions were provided.

Returns:

A storage tank object which can be passed as arguments to dynamic simulations and can calculate certain properties on its own.

Return type:

StorageTank

capacity(p, T, q=0, unit='mol')

Return the amount of fluid stored in the tank at given conditions.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the fluid being stored. Can vary between 0 and 1. The default is 0.

• unit (str, optional) – Unit of the capacity to be returned. Valid units are “mol” and “kg”. The default is “mol”.

Returns:

Amount of fluid stored.

Return type:

float

capacity_bulk(p, T, q=0, unit='mol')

Calculate the amount of bulk fluid in the tank.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the fluid being stored. Can vary between 0 and 1. The default is 0.

• unit (str, optional) – Unit of the capacity to be returned. Valid units are “mol” and “kg”. The default is “mol”.

Returns:

Amount of bulk fluid stored.

Return type:

float

find_quality_at_saturation_capacity(T, capacity)

Find vapor quality at the given temperature and capacity.

Parameters:

• T (float) – Temperature (K)

• capacity (float) – Amount of fluid in the tank (moles).

Returns:

Vapor quality of the fluid being stored. This is assuming that the fluid is on the saturation line.

Return type:

float

internal_energy(p, T, q=1)

Calculate the internal energy of the fluid inside of the tank.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the fluid being stored. The default is 1.

Returns:

Internal energy of the fluid being stored (J).

Return type:

float

conditions_at_capacity_temperature(cap, T, p_guess, q_guess)

Find conditions corresponding to a given capacity and temperature.

Parameters:

• cap (float) – Amount of fluid inside the tank (moles).

• T (float) – Temperature (K).

• p_guess (float) – Initial guess for pressure value (Pa) to be optimized.

• q_guess (float) – Initial guess for vaport quality value to be optimized.

Returns:

The optimization result represented as a OptimizeResult object. The relevant attribute for this method is x, the solution array. x[0] contains the pressure value and x[1] contains the vapor quality value.

Return type:

OptimizeResult

conditions_at_capacity_pressure(cap, p, T_guess, q_guess)

Find conditions corresponding to a given capacity and temperature.

Parameters:

• cap (float) – Amount of fluid inside the tank (moles).

• P (float) – Pressure (Pa).

• T_guess (float) – Initial guess for temperature value (K) to be optimized.

• q_guess (float) – Initial guess for vaport quality value to be optimized.

Returns:

The optimization result represented as a OptimizeResult object. The relevant attribute for this package is x, the solution array. x[0] contains the temperature value and x[1] contains the vapor quality value.

Return type:

scipy.optimize.OptimizeResult

calculate_dormancy(p, T, heating_power, q=0)

Calculate dormancy time given a constant heating rate.

Parameters:

• p (float) – Initial tank pressure (Pa).

• T (float) – Initial tank temperature (K).

• heating_power (float) – The heating power going into the tank during parking (W).

• q (float, optional) – Initial vapor quality of the tank. The default is 0 (pure liquid).

Returns:

Pandas dataframe containing calculation conditions and results. Each key stores a floating point number. The dictionary keys and their respective values are:

• ”init pressure”: initial pressure

• ”init temperature”: initial temperature

• ”init quality”: initial vapor quality

• ”dormancy time”: time until tank needs to be vented in seconds

• ”final temperature”: temperature of the tank as venting begins

• ”final quality”: vapor quality at the time of venting

• ”final pressure”: pressure at the time of venting

• ”capacity error”: error between final and initial capacity

• ”total energy change”: difference in internal energy between the initial and final conditions

• ”solid heat capacity contribution”: the amount of heat absorbed by the tank walls

Return type:

pd.DataFrame

thermal_res(p, T, time, env_temp)

Calculate the thermal resistance of the tank.

Parameters:

• p (float) – Pressure (Pa) of fluid inside tank.

• T (float) – Temperature (K) of fluid inside tank

• time (float) – Time elapsed in simulation (s).

• env_temp (float) – Temperature (K) of environment surrounding tank.

Returns:

Thermal resistance of the tank (K/W).

Return type:

float

class pytanksim.classes.SorbentTank(sorbent_material, aluminum_mass=0, carbon_fiber_mass=0, steel_mass=0, vent_pressure=None, min_supply_pressure=100000.0, thermal_resistance=0, surface_area=0, heat_transfer_coefficient=0, volume=None, set_capacity=None, full_pressure=None, empty_pressure=None, full_temperature=None, empty_temperature=None, full_quality=1, empty_quality=1, set_sorbent_fill=1)

Bases: StorageTank

Stores properties of a fluid storage tank filled with sorbents.

volume

Internal volume of the storage tank (m^3).

Type:

float

sorbent_material

An object storing the properties of the sorbent material used in the tank.

Type:

SorbentMaterial

aluminum_mass

The mass of aluminum making up the tank walls (kg). The default is 0.

Type:

float, optional

carbon_fiber_mass

The mass of carbon fiber making up the tank walls (kg). The default is 0.

Type:

float, optional

steel_mass

The mass of steel making up the tank walls (kg). The default is 0.

Type:

float, optional

vent_pressure

Maximum pressure at which the tank has to be vented (Pa). The default is None.

Type:

float, optional

min_supply_pressure

The minimum supply pressure (Pa) for discharging simulations. The default is 1E5.

Type:

float, optional

thermal_resistance

The thermal resistance of the tank walls (K/W). The default is 0.

Type:

Callable, optional

surface_area

Outer surface area of the tank in contact with the environment (m^2). The default is 0.

Type:

float, optional

heat_transfer_coefficient

The heat transfer coefficient of the tank surface (W/(m^2 K)). The default is 0.

Type:

Callable, optional

Initialize a SorbentTank object.

Parameters:

• sorbent_material (SorbentMaterial) – An object storing the properties of the sorbent material used in the tank.

• aluminum_mass (float, optional) – The mass of aluminum making up the tank walls (kg). The default is 0.

• carbon_fiber_mass (float, optional) – The mass of carbon fiber making up the tank walls (kg). The default is 0.

• steel_mass (float, optional) – The mass of steel making up the tank walls (kg). The default is 0.

• vent_pressure (float, optional) – Maximum pressure at which the tank has to be vented (Pa). The default is None.

• min_supply_pressure (float, optional) – The minimum supply pressure (Pa) for discharging simulations. The default is 1E5.

• thermal_resistance (Callable or float, optional) –

  A function which returns the thermal resistance of the tank walls (K/W) as a function of tank pressure (Pa), tank temperature (K), time (s), and temperature of surroundings (K). The default is 0. If a float is provided, it will be converted to a function which returns that value everywhere. If both this and the arguments ‘surface_area’ and ‘heat_transfer_coefficient’ are passed, two values of thermal resistance will be calculated and the highest value between the two will be taken at each time step. Thus, to avoid confusion, one should either: (a) use the other two arguments together, or (b) use this one, but not both at the same time.

  If a callable is passed, it must have the signature:

  def tr_function(p, T, time, env_temp):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      # 'env_temp' is the temperature of surroundings (K)
      ....
      # Returned is the thermal resistance (K/W)
      return tr_value
  

• surface_area (float, optional) – Outer surface area of the tank in contact with the environment (m^2). The default is 0.

• heat_transfer_coefficient (Callable or float, optional) –

  A function which returns the heat transfer coefficient of the tank walls (W/(m^2 K)) as a function of tank pressure (Pa), tank temperature (K), time (s), and temperature of surroundings (K). The default is 0. If a float is provided, it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def htc_function(p, T, time, env_temp):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      # 'env_temp' is the temperature of surroundings (K)
      ....
      # Returned is the heat transfer coefficient (W/(m^2 K))
      return heat_transfer_coef
  

• volume (float, optional) – Internal volume of the storage tank (m^3). The default is None. This value is required unless the set capacity and operating conditions are defined, in which case the volume is calculated from the capacity and operating conditions.

• set_capacity (float, optional) – Set internal capacity of the storage tank (mol). The default is None. If specified, this will override the user-specified tank volume.

• full_pressure (float, optional) – Pressure (Pa) of the tank when it is considered full. The default is None.

• empty_pressure (float, optional) – Pressure (Pa) of the tank when it is considered empty. The default is None.

• full_temperature (float, optional) – Temperature (K) of the tank when it is considered full. The default is None.

• empty_temperature (float, optional) – Temperature (K) of the tank when it is considered empty. The default is None.

• full_quality (float, optional) – Vapor quality of the tank when it is considered full. The default is 1 (Gas).

• empty_quality (float, optional) – Vapor quality of the tank when it is considered empty. The default is 1 (Gas).

• set_sorbent_fill (float, optional) – Ratio of tank volume filled with sorbent. The default is 1 (completely filled with sorbent).

Returns:

Object which stores various properties of a storage tank containing sorbents. It also has some useful methods related to the tank, most notably dormancy calculation.

Return type:

SorbentTank

bulk_fluid_volume(p, T)

Calculate the volume of bulk fluid inside of the tank.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature(K).

Returns:

Bulk fluid volume within the tank (m^3).

Return type:

float

capacity(p, T, q=0)

Return the amount of fluid stored in the tank at given conditions.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the fluid being stored. Can vary between 0 and 1. The default is 0.

Returns:

Amount of fluid stored (moles).

Return type:

float

capacity_bulk(p, T, q=0)

Calculate the amount of bulk fluid in the tank.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the fluid being stored. Can vary between 0 and 1. The default is 0.

Returns:

Amount of bulk fluid stored (moles).

Return type:

float

internal_energy(p, T, q=1)

Calculate the internal energy of the fluid inside of the tank.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the fluid being stored. The default is 1.

Returns:

Internal energy of the fluid being stored (J).

Return type:

float

internal_energy_sorbent(p, T, q=1)

Calculate the internal energy of the adsorbed fluid in the tank.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the fluid being stored. The default is 1.

Returns:

Internal energy of the adsorbed fluid in the tank (J).

Return type:

float

internal_energy_bulk(p, T, q=1)

Calculate the internal energy of the bulk fluid in the tank.

Parameters:

• p (float) – Pressure (Pa).

• T (float) – Temperature (K).

• q (float, optional) – Vapor quality of the fluid being stored. The default is 1.

Returns:

Internal energy of the bulk fluid in the tank (J).

Return type:

float

find_quality_at_saturation_capacity(T, capacity)

Find vapor quality at the given temperature and capacity.

Parameters:

• T (float) – Temperature (K)

• capacity (float) – Amount of fluid in the tank (moles).

Returns:

Vapor quality of the fluid being stored. This is assuming that the fluid is on the saturation line.

Return type:

float

find_temperature_at_saturation_quality(q, cap)

Find temperature at a given capacity and vapor quality value.

Parameters:

• q (float) – Vapor quality. Can vary between 0 and 1.

• cap (float) – Amount of fluid stored in the tank (moles).

Returns:

The optimization result represented as a OptimizeResult object. The relevant attribute for this function is x, the optimized temperature value.

Return type:

scipy.optimize.OptimizeResult

calculate_dormancy(p, T, heating_power, q=0)

Calculate dormancy time given a constant heating rate.

Parameters:

• p (float) – Initial tank pressure (Pa).

• T (float) – Initial tank temperature (K).

• heating_power (float) – The heating power going into the tank during parking (W).

• q (float, optional) – Initial vapor quality of the tank. The default is 0 (pure liquid).

Returns:

Pandas dataframe containing calculation conditions and results. Each key stores a floating point number. The dictionary keys and their respective values are:

• ”init pressure”: initial pressure

• ”init temperature”: initial temperature

• ”init quality”: initial vapor quality

• ”dormancy time”: time until tank needs to be vented in seconds

• ”final temperature”: temperature of the tank as venting begins

• ”final quality”: vapor quality at the time of venting

• ”final pressure”: pressure at the time of venting

• ”capacity error”: error between final and initial capacity

• ”total energy change”: difference in internal energy between the initial and final conditions

• ”sorbent energy contribution”: the amount of heat taken by the adsorbed phase via desorption

• ”bulk energy contribution”: the amount of heat absorbed by the bulk phase

• ”immersion heat contribution”: how much heat has been absorbed by un-immersing the sorbent material in the fluid

• ”solid heat capacity contribution”: the amount of heat absorbed by the tank walls

Return type:

pd.DataFrame

class pytanksim.classes.SimResults(pressure, temperature, time, moles_adsorbed, moles_gas, moles_liquid, moles_supercritical, tank_params, sim_params, stop_reason, sim_type=None, inserted_amount=0, flow_energy_in=0, cooling_required=0, heating_required=0, cooling_additional=0, heating_additional=0, heat_leak_in=0, vented_amount=0, vented_energy=0)

Class for storing the results of dynamic simulations.

It comes with methods for exporting the results to csv, plotting the results, and for combining the results of multiple simulations.

df

A dataframe containing the results of dynamic simulations. See notes for the column names and the variables each column has.

Type:

pd.DataFrame

Notes

Below is a list of the pandas DataFrame column names and a short description of the variable stored inside each series.

• t: time (seconds)

• p: pressure (Pa)

• T: temperature (K)

• na: amount of fluid adsorbed (moles)

• ng: amount of fluid in gaseous form (moles)

• nl: amount of fluid in liquid form (moles)

• ns: amount of fluid in supercritical form (moles)

• Qcoolreq: cumulative amount of cooling required (J)

• Qheatreq: cumulative amount of heating required (J)

• nout: cumulative amount of fluid vented (moles)

• Hout: cumulative amount of vented fluid enthalpy (J)

• nin: cumulative amount of fluid inserted (moles)

• Hin: cumulative amount of inserted fluid enthalpy (J)

• Qcooladd: cumulative amount of user specified cooling (J)

• Qheatadd: cumulative amount of user specified heating (J)

• Qleak: cumulative amount of heat leakage into the tank (J)

• ma: mass of fluid adsorbed (kg)

• mg: mass of fluid in gaseous form (kg)

• ml: mass of fluid in liquid form (kg)

• ms: mass of fluid in supercritical form (kg)

• mout: cumulative mass of fluid vented (kg)

• min: cumulative mass of fluid inserted (kg)

• na_dot: the amount of fluid (moles) being adsorbed per second.

• ng_dot: the first derivative of the amount of fluid in gaseous form w.r.t. time. Its unit is mol/s.

• nl_dot: the first derivative of the amount of fluid in liquid form w.r.t. time. Its unit is mol/s

• ns_dot: the first derivative of the amount of fluid in supercritical form w.r.t. time. Its unit is mol/s.

• Qcoolreq_dot: the cooling power (W) required to maintain a constant pressure during refuel.

• Qheatreq_dot: the heating power (W) required to maintain a constant pressure during discharge.

• nout_dot: the rate at which fluid is being vented from the tank (mol/s).

• Hout_dot: the rate at which enthalpy is taken away by fluid leaving the tank (W).

• nin_dot: the rate at which fluid is entering the tank (mol/s).

• Hin_dot: the rate at which enthalpy is added by fluid fluid entering the tank (W).

• Qcooladd_dot: the user specified cooling power (W).

• Qheatadd_dot: the user specified heating power (W).

• Qleak_dot: the rate of heat leakage into the tank (W).

• ma_dot: the mass of fluid (kg) being adsorbed per second.

• mg_dot: the first derivative of the mass of fluid in gaseous form w.r.t. time. Its unit is kg/s.

• ml_dot: the first derivative of the mass of fluid in liquid form w.r.t. time. Its unit is kg/s.

• ms_dot: the first derivative of the mass of fluid in supercritical form w.r.t. time. Its unit is kg/s.

• mout_dot: the rate at which fluid is being vented from the tank (kg/s).

• min_dot: the rate at which fluid is being inserted into the tank (kg/s).

Initialize a SimResults object.

Parameters:

• pressure (Union[List[float], np.ndarray]) – A list or numpy array containing the pressure values inside of the tank (Pa) as it changes over time.

• temperature (Union[List[float], np.ndarray]) – A list or numpy array containing the temperature values inside of the tank (K) as it changes over time.

• time (Union[List[float], np.ndarray]) – A list or numpy array containing the simulation time points (s) at which results are reported.

• moles_adsorbed (Union[List[float], np.ndarray]) – A list or numpy array containing the amount of fluid that is adsorbed (moles) at given points in time.

• moles_gas (Union[List[float], np.ndarray]) – A list or numpy array containing the amount of fluid stored in gaseous form (moles) at given points in time.

• moles_liquid (Union[List[float], np.ndarray]) – A list or numpy array containing the amount of fluid stored in liquid form (moles) at given points in time.

• moles_supercritical (Union[List[float], np.ndarray]) – A list or numpy array containing the amount of supercritical fluid in the tank (moles) at given points in time.

• tank_params (Union[StorageTank, SorbentTank]) – An object containing the parameters of the storage tank used for the dynamic simulation.

• sim_type (str) – A string describing the type of simulation that was conducted.

• sim_params (SimParams) – An object containing the parameters used for the simulation.

• stop_reason (str) – A string describing why the simulation was terminated.

• inserted_amount (Union[List[float], np.ndarray], optional) – The cumulative amount of fluid inserted into the tank (moles) throughout the dynamic simulation. The default is 0.

• flow_energy_in (Union[List[float], np.ndarray], optional) – The cumulative amount of enthalpy brought by fluid flowing into the tank (J) throughout the dynamic simulation. The default is 0.

• cooling_required (Union[List[float], np.ndarray], optional) – The cumulative amount of cooling required (J) to maintain a constant pressure during refueling. The default is 0.

• heating_required (Union[List[float], np.ndarray], optional) – The cumulative amount of heating required (J) to maintain a constant pressure during discharging. The default is 0.

• cooling_additional (Union[List[float], np.ndarray], optional) – The cumulative amount of additional cooling (J) inputted to the simulation via a user-defined function. The default is 0.

• heating_additional (Union[List[float], np.ndarray], optional) – The cumulative amount of additional heating (J) inputted to the simulation via a user-defined function. The default is 0.

• heat_leak_in (Union[List[float], np.ndarray], optional) – The cumulative amount of heat (J) which has leaked into the tank from the environment. The default is 0.

• vented_amount (Union[List[float], np.ndarray], optional) – The cumulative amount of fluid vented (moles) throughout the dynamic simulation. The default is 0.

• vented_energy (Union[List[float], np.ndarray], optional) – The cumulative amount of enthalpy taken by fluid flowing out of the tank (J) throughout the dynamic simulation. The default is 0.

Returns:

An object containing the results of a dynamic simulation run by pytanksim. It has functions for exporting and plotting.

Return type:

SimResults

get_final_conditions(idx=- 1)

Output final tank conditions at the end of the simulation.

Parameters:

idx (int, optional) – The index of the simulation results array from which the values are to be taken. The default is -1 (the last time point in the simulation).

Returns:

A dictionary containing tank conditions at’idx’.

Return type:

dict

to_csv(filename, verbose=True)

Export simulation results to a csv file.

Parameters:

• filename (str) – The desired filepath for the csv file to be created.

• verbose (bool, optional) – Whether or nor to report the completion of the export. The default value is True.

classmethod from_csv(filename, import_components=False)

Import simulation results from a csv file.

Parameters:

• filename (str) – Path to a csv file which was exported by pytanksim.

• import_components (bool) – If True, this function will return a tuple with contents as follows: SimResults, StorageTank, SimParams. If False, this function will only return the SimResults object. The default option is False.

Returns:

A single object containing the simulation results, or a tuple with SimResults, StorageTank, and SimParams objects.

Return type:

SimResults|Tuple

interpolate(x_var='t')

Interpolate simulation results between points.

Parameters:

x_var (str, optional) – Variable to be used as a basis/input for interpolation.The default is “t”.

Returns:

A dictionary containing functions which interpolate each variable in the SimResults object w.r.t. the variable chosen in x_var.

Return type:

“dict[Callable[[float], float]]”

plot(x_axis, y_axes, colors=['r', 'b', 'g'])

Plot the results of the simulation.

Parameters:

• x_axis (str) – A string specifying what variable should be on the x-axis. See notes for valid inputs.

• y_axes (Union[str, List[str]]) – A string or a list of strings specifying what is to be plotted on the y-axis. See notes for valid inputs

• colors (Union[str, List[str]], optional) – A string or a list of strings specifying colors for the lines in the plot. The default is [“r”, “b”, “g”].

Raises:

ValueError – If more than 3 y-variables are specified to be plotted.

Returns:

A matplolib axis or a numpy array of several axes.

Return type:

Union[np.ndarray, plt.Axes]

Notes

Below is a list of valid string inputs for x_axis and y_axes along with the variables they represent.

• t: time (seconds)

• p: pressure (Pa)

• T: temperature (K)

• na: amount of fluid adsorbed (moles)

• ng: amount of fluid in gaseous form (moles)

• nl: amount of fluid in liquid form (moles)

• ns: amount of fluid in supercritical form (moles)

• Qcoolreq: cumulative amount of cooling required (J)

• Qheatreq: cumulative amount of heating required (J)

• nout: cumulative amount of fluid vented (moles)

• Hout: cumulative amount of vented fluid enthalpy (J)

• nin: cumulative amount of fluid inserted (moles)

• Hin: cumulative amount of inserted fluid enthalpy (J)

• Qcooladd: cumulative amount of user specified cooling (J)

• Qheatadd: cumulative amount of user specified heating (J)

• Qleak: cumulative amount of heat leakage into the tank (J)

• ma: mass of fluid adsorbed (kg)

• mg: mass of fluid in gaseous form (kg)

• ml: mass of fluid in liquid form (kg)

• ms: mass of fluid in supercritical form (kg)

• mout: cumulative mass of fluid vented (kg)

• min: cumulative mass of fluid inserted (kg)

• na_dot: the amount of fluid (moles) being adsorbed per second.

• ng_dot: the first derivative of the amount of fluid in gaseous form w.r.t. time. Its unit is mol/s.

• nl_dot: the first derivative of the amount of fluid in liquid form w.r.t. time. Its unit is mol/s

• ns_dot: the first derivative of the amount of fluid in supercritical form w.r.t. time. Its unit is mol/s.

• Qcoolreq_dot: the cooling power (W) required to maintain a constant pressure during refuel.

• Qheatreq_dot: the heating power (W) required to maintain a constant pressure during discharge.

• nout_dot: the rate at which fluid is being vented from the tank (mol/s).

• Hout_dot: the rate at which enthalpy is taken away by fluid leaving the tank (W).

• nin_dot: the rate at which fluid is entering the tank (mol/s).

• Hin_dot: the rate at which enthalpy is added by fluid fluid entering the tank (W).

• Qcooladd_dot: the user specified cooling power (W).

• Qheatadd_dot: the user specified heating power (W).

• Qleak_dot: the rate of heat leakage into the tank (W).

• ma_dot: the mass of fluid (kg) being adsorbed per second.

• mg_dot: the first derivative of the mass of fluid in gaseous form w.r.t. time. Its unit is kg/s.

• ml_dot: the first derivative of the mass of fluid in liquid form w.r.t. time. Its unit is kg/s.

• ms_dot: the first derivative of the mass of fluid in supercritical form w.r.t. time. Its unit is kg/s.

• mout_dot: the rate at which fluid is being vented from the tank (kg/s).

• min_dot: the rate at which fluid is being inserted into the tank (kg/s).

classmethod combine(sim_results_list)

Combine the results of several simulations into a single object.

Parameters:

sim_results_list ("List[SimResults]") – A list of SimResults objects from several different simulations.

Returns:

A single object containing the combined simulation results.

Return type:

SimResults

class pytanksim.classes.SimParams

A class to store simulation parameters.

This data class stores the parameters of the tank at the start of the simulation as well as the conditions specified to stop the simulation. Additionally, it also stores the setting for the number of data points to be reported at the end of the simulation.

init_temperature

The temperature (K) of the tank being simulated at the beginning of the simulation.

Type:

float

init_pressure

The pressure of the tank being simulated (Pa) at the beginning of the simulation. The default value is 1E5. This parameter was made optional as the two-phase simulations did not require it to be filled, rather pytanksim will automatically calculate the saturation pressure given a starting temperature.

Type:

float, optional

final_time

The time (seconds) at which the simulation is to be stopped.

Type:

float

init_time

The time (seconds) at which the beginning of the simulation is set to. The default value is set to 0 seconds.

Type:

float, optional

displayed_points

The number of data points to be reported at the end of the simulation. The default is 200.

Type:

int, optional

target_temp

The target temperature (K) at which the simulation is to be stopped. The default value is 0, which effectively means the simulation does not have a set temperature at which the simulation is stopped.

Type:

float, optional

target_pres

The target pressure (Pa) at which the simulation is to be stopped. The default value is 0, which effectively means the simulation does not have a set pressure at which the simulation is stopped.

Type:

float, optional

stop_at_target_pressure

If True, it will stop the simulation when the target pressure is met. The default is False.

Type:

bool, optional

stop_at_target_temp

If True, it will stop the simulation when the target temperature is met. The default is False.

Type:

bool, optional

target_capacity

The amount of fluid (moles) stored in the tank at which the simulation is to be stopped. The default is 0.

Type:

float, optional

init_ng

The initial amount of gas (moles) stored in the tank at the beginning of the simulation. The default value is 0.

Type:

float, optional

init_nl

The initial amount of liquid (moles) stored in the tank at the beginning of the simulation. The default value is 0.

Type:

float, optional

init_q

The initial quality of the fluid being stored. It can vary between 0 and 1. The default is None.

Type:

float, optional

Parameters:

• inserted_amount (float, optional) – The amount of fluid which has been previously inserted into the tank (moles) at the beginning of the simulation. Used to track refueling processes across multiple simulations. The default value is 0.

• vented_amount (float, optional) – The amount of fluid which has been previously vented from the tank (moles) at the beginning of the simulation. Used to track discharging and boil-off processes across multiple simulations. The default value is 0.

• cooling_required (float, optional) – The cumulative amount of required cooling (J) to maintain a constant pressure prior to the start of a simulation. The default value is 0. Useful when restarting a stopped cooled refuel simulation.

• heating_required (float, optional) – The cumulative amount of required heating (J) to maintain a constant pressure prior to the start of a simulation. The default value is 0. Useful when restarting a stopped heated discharge simulation.

• vented_energy (float, optional) – Cumulative amount of enthalpy (J) contained in the fluid vented prior to the start of the simulation. The default is 0. Useful when stopping and restarting discharge simulations.

• flow_energy_in (float, optional) – Cumulative amount of enthalpy (J) contained in the fluid inserted prior to the start of the simulation. The default is 0. Useful when stopping and restarting refueling simulations.

• cooling_additional (float, optional) – The cumulative amount of user-specified cooling (J) prior to the start of a simulation. The default value is 0. Useful when stopping and restarting simulations with user-specified cooling.

• heating_additional (float, optional) – The cumulative amount of user-specified cooling (J) prior to the start of a simulation. The default value is 0. Useful when stopping and restarting simulations with user-specified heating.

• heat_leak_in (float, optional) – The cumulative amount of heat (J) which has leaked into the tank prior to the start of a simulation. The default value is 0. Useful when stopping and restarting simulations involving heat leakage.

• verbose (bool, optional) – Whether or not the simulation will print out its progress bars and give a notification once it has finished. The default value is True.

classmethod from_SimResults(sim_results, displayed_points=None, init_time=None, final_time=None, target_pres=None, target_temp=None, stop_at_target_pressure=None, stop_at_target_temp=None, target_capacity=None, verbose=None)

Take final conditions from a previous simulation as new parameters.

Parameters:

• sim_results (SimResults) – An object containing previous simulation results.

• displayed_points (float, optional) – The number of data points to be reported at the end of the simulation. The default is 200.

• init_time (float, optional) – The time (seconds) at which the beginning of the simulation is set. The default value is None.

• final_time (float, optional) – The time (seconds) at which the simulation is to be stopped. If None, then the final_time setting from the previous simulation is used. The default is None.

• target_pres (float, optional) – The target pressure (Pa) at which the simulation is to be stopped. If None, then the target_pres setting from the previous simulation is used. The default is None.

• target_temp (float, optional) – The target temperature (K) at which the simulation is to be stopped. If None, then the target_temp setting from the previous simulation is used. The default is None.

• stop_at_target_pressure (bool, optional) – If True, it will stop the simulation when the target pressure is met. If None, then the stop_at_target_pressure setting from the previous simulation is used. The default is None.

• stop_at_target_temp (bool, optional) – If True, it will stop the simulation when the target temperature is met. If None, then the stop_at_target_temp setting from the previous simulation is used. The default is None.

• target_capacity (float, optional) – The amount of fluid (moles) stored in the tank at which the simulation is to be stopped. If None, then the target_capacity value from the previous simulation is used. The default is None.

Returns:

A SimParams object containing the final conditions taken from sim_results set as the new starting parameters.

Return type:

SimParams

class pytanksim.classes.BoundaryFlux(mass_flow_in=0.0, mass_flow_out=0.0, heating_power=0.0, cooling_power=0.0, pressure_in=None, temperature_in=None, environment_temp=0, enthalpy_in=None, enthalpy_out=None, heat_leak_in=None)

Stores information of the mass and energy fluxes on the tank boundaries.

mass_flow_in

A function which returns mass flow into the tank (kg/s) as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is a function which returns 0 everywhere.

Type:

Callable[[float, float, float], float], optional

mass_flow_out

A function which returns mass flow exiting the tank (kg/s) as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is a function which returns 0 everywhere.

Type:

Callable[[float, float, float], float], optional

heating_power

A function which returns heating power added to the tank (W) as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is a function which returns 0 everywhere.

Type:

Callable[[float, float, float], float], optional

cooling_power

A function which returns cooling power added to the tank (W) as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is a function which returns 0 everywhere.

Type:

Callable[[float, float, float], float], optional

pressure_in

A function which returns the pressure (Pa) of the fluid being inserted into the tank as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is None.

Type:

Callable[[float, float, float], float], optional

temperature_in

A function which returns the temperature (K) of the fluid being inserted into the tank as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is None.

Type:

Callable[[float, float, float], float], optional

environment_temp

The temperature (K) of the environment surrounding the tank. This value is used in the dynamic simulation to calculate heat leakage into the tank. The default is 0, in which case heat leakage into the tank is not considered.

Type:

float, optional

enthalpy_in

A function which returns the enthalpy (J/mol) of the fluid being inserted into the tank as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is None.

Type:

Callable[[float, float, float], float], optional

enthalpy_out

A function which returns the enthalpy (J/mol) of the fluid exiting the tank as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is None.

Type:

Callable[[float, float, float], float], optional

heat_leak_in

A function which returns the heat (J/mol) leaking into the tank as a function of tank pressure (Pa), tank temperature (K), time (s), and temperature of tank surroundings (K). The default is None.

Type:

Callable[[float, float, float,float], float], optional

Initialize a BoundaryFlux object.

Parameters:

• mass_flow_in (Callable or float, optional) –

  A function which returns mass flow into the tank (kg/s) as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is a function which returns 0 everywhere. If a float is provided, it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def mass_flow_in_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      #Returned is the mass flow going into the tank (kg/s)
      return mass_flow_in
  

• mass_flow_out (Callable or float, optional) –

  A function which returns mass flow exiting the tank (kg/s) as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is a function which returns 0 everywhere. If a float is provided it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def mass_flow_out_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      # Returned is the mass flow going out of the tank (kg/s)
      return mass_flow_out
  

• heating_power (Callable or float, optional) –

  A function which returns heating power added to the tank (W) as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is a function which returns 0 everywhere. If a float is provided, it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def heating_power_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      # Returned is the heat put into the tank (W)
      return heating_power
  

• cooling_power (Callable or float, optional) –

  A function which returns cooling power added to the tank (W) as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is a function which returns 0 everywhere. If a float is provided,it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def cooling_power_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      # Returned is the heat taken out of the tank (W)
      return cooling_power
  

• pressure_in (Callable or float, optional) –

  A function which returns the pressure (Pa) of the fluid being inserted into the tank as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is None. If a float is provided,it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def pressure_in_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      # Returned is the pressure (Pa) of the fluid going into
      # the tank.
      return pressure_in
  

• temperature_in (Callable or float, optional) –

  A function which returns the temperature (K) of the fluid being inserted into the tank as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is None. If a float is provided,it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def temperature_in_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      # Returned is the temperature (K) of the fluid going into
      # the tank.
      return temperature_in
  

• environment_temp (Callable or float, optional) –

  The temperature (K) of the environment surrounding the tank. This value is used in the dynamic simulation to calculate heat leakage into the tank. It can be provided either as a float or as a function of tank pressure (Pa), tank temperature (K). The default is 0, in which case heat leakage into the tank is not considered.

  If a callable is passed, it must have the signature:

  def env_temp_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      # Returned is the temperature of the surroundings in the
      # unit of K.
      return enthalpy_in
  

• enthalpy_in (Callable or float, optional) –

  A function which returns the enthalpy (J/mol) of the fluid being inserted into the tank as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is None. If a float is provided,it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def enthalpy_in_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      # Returned is the enthalpy (J/mol) of the fluid going into
      # the tank.
      return enthalpy_in
  

• enthalpy_out (Callable or float, optional) –

  A function which returns the enthalpy (J/mol) of the fluid exiting the tank as a function of tank pressure (Pa), tank temperature (K), and time (s). The default is None. If a float is provided, it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def enthalpy_out_function(p, T, time):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      ....
      # Returned is the enthalpy (J/mol) of the fluid going out
      # of the tank.
      return enthalpy_out
  

• heat_leak_in (Callable or float, optional) –

  A function which returns the amount of heat leakage into the tank (W) as a function of tank pressure (Pa), tank temperature (K), time (s), and temperature of surroundings (K). The default is None, which will use the thermal resistance calculation from the storage tank. Otherwise, it will override that calculation. If a float is provided, it will be converted to a function which returns that value everywhere.

  If a callable is passed, it must have the signature:

  def enthalpy_out_function(p, T, time, env_temp):
      # 'p' is tank pressure (Pa)
      # 'T' is tank temperature (K)
      # 'time' is the time elapsed within the simulation (s)
      # 'env_temp' is the temperature of surroundings (K)
      ....
      # Returned is the enthalpy (J/mol) of the fluid going out
      # of the tank.
      return enthalpy_out
  

Raises:

ValueError – If the mass flow going in is specified but the parameters that specify its enthalpy (i.e., either pressure and temperature or its enthalpy value) are not specified.

Returns:

An object which stores information of the mass and energy fluxes on the tank boundaries.

Return type:

BoundaryFlux

class pytanksim.classes.BaseSimulation(simulation_params, storage_tank, boundary_flux)

An abstract base class for dynamic simulations.

Other simulation classes inherit some attributes and methods from this class.

sim_type

Type of simulation (default, heated discharge, cooled refuel, etc.)

Type:

str

sim_phase

1 or 2 phases.

Type:

int

simulation_params

Object which stores simulation parameters.

Type:

SimParams

storage_tank

Object which stores the properties of the tank being simulated.

Type:

StorageTank

boundary_flux

Object which stores the amount of energy entering and exiting the tank.

Type:

BoundaryFlux

stop_reason

A string stating the reason for the simulation to have stopped. It will be passed to the SimResults object once the simulation finishes.

Type:

str

Initialize the BaseSimulation class.

heat_leak_in(p, T, time)

Calculate the heat leakage rate from the environment into the tank.

Parameters:

• p (float) – Pressure (Pa) of the storage tank.

• T (float) – Temperature (K) of the storage tank.

• time (float) – Simulation time (s)

Returns:

The rate of heat leakage into the tank from the environment (W).

Return type:

float

abstract run()

Abstract function which will be defined in the child classes.

Raises:

NotImplementedError – Raises an error since it is not implemented in this abstract base class.

Return type:

None.

enthalpy_in_calc(p, T, time)

Calculate the enthalpy (J/mol) of fluid going into the tank.

Parameters:

• p (float) – Pressure inside of the tank (Pa)

• T (float) – Temperature inside of the tank (K)

• time (float) – Time (s) in the simulation.

Returns:

Enthalpy of the fluid going into the tank (J/mol).

Return type:

float

enthalpy_out_calc(fluid_property_dict, p, T, time)

Calculate the enthalpy (J/mol) of fluid going out of the tank.

Parameters:

• fluid_property_dict (Dict[str,float]) – A dictionary of properties of the fluid being stored inside of the tank. In the case of the two phase simulation, it is the properties of the gas and not the liquid. For this function, this dictionary must return an enthalpy (J/mol) value given the key “hf”.

• p (float) – Pressure inside of the tank (Pa)

• T (float) – Temperature inside of the tank (K)

• time (float) – Time (s) in the simulation.

Returns:

Enthalpy of the fluid going out of the tank (J/mol).

Return type:

float

class pytanksim.classes.OnePhaseSorbentSim(simulation_params, storage_tank, boundary_flux)

Bases: pytanksim.classes.basesimclass.BaseSimulation

Base class for simulation of sorbent tanks in the one phase region.

It includes functions to calculate the governing ODE

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

class pytanksim.classes.OnePhaseSorbentDefault(simulation_params, storage_tank, boundary_flux)

Bases: OnePhaseSorbentSim

Simulates sorbent tanks in the one phase region without constraints.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(p, T, time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• p (float) – Current pressure (Pa).

• T (float) – Current temperature (K).

• time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as hitting the saturation line, or hitting the maximum pressure limit of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.OnePhaseSorbentVenting(simulation_params, storage_tank, boundary_flux)

Bases: OnePhaseSorbentSim

Sorbent tank venting at constant pressure in the one phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(T, time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• T (float) – Current temperature (K).

• time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as hitting the saturation line, or hitting the maximum pressure limit of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.OnePhaseSorbentCooled(simulation_params, storage_tank, boundary_flux)

Bases: OnePhaseSorbentSim

Sorbent tank cooled at constant pressure in the one phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(T, time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• T (float) – Current temperature (K).

• time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as hitting the saturation line, or hitting the maximum pressure limit of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.OnePhaseSorbentHeatedDischarge(simulation_params, storage_tank, boundary_flux)

Bases: OnePhaseSorbentSim

Sorbent tank heated at constant pressure in the one phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(T, time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• T (float) – Current temperature (K).

• time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as hitting the saturation line, or hitting the maximum pressure limit of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.TwoPhaseSorbentSim(simulation_params, storage_tank, boundary_flux)

Bases: pytanksim.classes.basesimclass.BaseSimulation

Base class for sorbent tanks in the two-phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

class pytanksim.classes.TwoPhaseSorbentDefault(simulation_params, storage_tank, boundary_flux)

Bases: TwoPhaseSorbentSim

Simulate sorbent tanks in the two phase region without constraints.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(ng, nl, T, time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• time (float) – Current time step (in s).

• ng (float) – Current amount of gas in the tank (moles).

• nl (float) – Current amount of liquid in the tank (moles).

• T (float) – Current temperature (K).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as the end of the phase change, or if the simulation hits the maximum pressure of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.TwoPhaseSorbentVenting(simulation_params, storage_tank, boundary_flux)

Bases: TwoPhaseSorbentSim

Sorbent tank venting at constant pressure in the two-phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(ng, nl, time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• ng (float) – Current amount of gas in the tank (moles).

• nl (float) – Current amount of liquid in the tank (moles).

• time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as the end of the phase change, or if the simulation hits the maximum pressure of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.TwoPhaseSorbentCooled(simulation_params, storage_tank, boundary_flux)

Bases: TwoPhaseSorbentSim

Sorbent tank cooled at constant pressure in the two-phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time, ng, nl)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• time (float) – Current time step (in s).

• ng (float) – Current amount of gas in the tank (moles).

• nl (float) – Current amount of liquid in the tank (moles).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as the end of the phase change, or if the simulation hits the maximum pressure of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.TwoPhaseSorbentHeatedDischarge(simulation_params, storage_tank, boundary_flux)

Bases: TwoPhaseSorbentSim

Sorbent tank heated at constant pressure in the two-phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time, ng, nl)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• ng (float) – Current amount of gas in the tank (moles).

• nl (float) – Current amount of liquid in the tank (moles).

• time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as the end of the phase change, or if the simulation hits the maximum pressure of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.OnePhaseFluidSim(simulation_params, storage_tank, boundary_flux)

Bases: pytanksim.classes.basesimclass.BaseSimulation

Base class for one phase fluid simulations.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

class pytanksim.classes.OnePhaseFluidDefault(simulation_params, storage_tank, boundary_flux)

Bases: OnePhaseFluidSim

Class for simulating fluid storage dynamics in the one phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time, p, T)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• time (float) – Current time step (in s).

• p (float) – Current pressure (Pa).

• T (float) – Current temperature (K).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as hitting the saturation line, or hitting the maximum pressure limit of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.OnePhaseFluidVenting(simulation_params, storage_tank, boundary_flux)

Bases: OnePhaseFluidSim

Simulate the dynamics of a fluid tank venting at constant pressure.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time, T)

Solve for the right hand side of the governing ODE.

Parameters:

• time (float) – Current time step in the simulation (s).

• T (float) – Current temperature (K).

Returns:

Numpy array containing values for the RHS of the governing ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as hitting the saturation line, or hitting the maximum pressure limit of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.OnePhaseFluidCooled(simulation_params, storage_tank, boundary_flux)

Bases: OnePhaseFluidSim

Simulates a tank being cooled to maintain constant pressure.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time, T)

Solve for the right hand side of the governing ODE.

Parameters:

• time (float) – Current time step in the simulation (s).

• T (float) – Current temperature (K).

Returns:

Numpy array containing values for the RHS of the governing ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as hitting the saturation line, or hitting the maximum pressure limit of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.OnePhaseFluidHeatedDischarge(simulation_params, storage_tank, boundary_flux)

Bases: OnePhaseFluidSim

Simulates a tank being heated to discharge at a constant pressure.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time, T)

Solve for the right hand side of the governing ODE.

Parameters:

• time (float) – Current time step in the simulation (s).

• T (float) – Current temperature (K).

Returns:

Numpy array containing values for the RHS of the governing ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as hitting the saturation line, or hitting the maximum pressure limit of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.TwoPhaseFluidSim(simulation_params, storage_tank, boundary_flux)

Bases: pytanksim.classes.basesimclass.BaseSimulation

Base class for the simulation of fluid tanks in the two-phase region.

Contains functions for calculating the governing ODEs.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

class pytanksim.classes.TwoPhaseFluidDefault(simulation_params, storage_tank, boundary_flux)

Bases: TwoPhaseFluidSim

Simulation of fluid tanks in the two-phase region w/o constraints.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time, ng, nl, T)

Find the right hand side of the governing ODE at a given time step.

Parameters:

• time (float) – Current time step (in s).

• ng (float) – Current amount of gas in the tank (moles).

• nl (float) – Current amount of liquid in the tank (moles).

• T (float) – Current temperature (K).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as the end of the phase change, or if the simulation hits the maximum pressure of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.TwoPhaseFluidVenting(simulation_params, storage_tank, boundary_flux)

Bases: TwoPhaseFluidSim

Fluid tank venting at constant pressure in the two-phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as the end of the phase change, or if the simulation hits the maximum pressure of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.TwoPhaseFluidCooled(simulation_params, storage_tank, boundary_flux)

Bases: TwoPhaseFluidSim

Fluid tank being cooled at constant pressure in the two-phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as the end of the phase change, or if the simulation hits the maximum pressure of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults

class pytanksim.classes.TwoPhaseFluidHeatedDischarge(simulation_params, storage_tank, boundary_flux)

Bases: TwoPhaseFluidSim

Fluid tank being heated at constant pressure in the two-phase region.

Initialize the BaseSimulation class.

Parameters:

• simulation_params (SimParams) – Object containing simulation-specific parameters.

• storage_tank (StorageTank) – Object containing attributes and methods specific to the storage tank being simulated.

• boundary_flux (BoundaryFlux) – Object containing information on the mass and energy going in and out of the tank during the simulation.

Raises:

• ValueError – If the simulation is set to begin on the saturation line but the initial values for liquid and gas in the tank, or, alternatively, the initial vapor quality, was not specified.

• ValueError – If both the initial values for liquid and gas in the tank is specified as well as the initial vapor quality, but the values don’t match each other.

Returns:

A simulation object which can be run to get results.

Return type:

BaseSimulation

solve_differentials(time)

Find the right hand side of the governing ODE at a given time step.

Parameters:

time (float) – Current time step (in s).

Returns:

An array containing the right hand side of the ODE.

Return type:

np.ndarray

run()

Run the dynamic simulation.

Raises:

TerminateSimulation – Stops the simulation when it detects an event such as the end of the phase change, or if the simulation hits the maximum pressure of the tank.

Returns:

An object for storing and manipulating the results of the dynamic simulation.

Return type:

SimResults