How to use apparent and true chemical species
In ProteusLib, most all chemical processes simulated will be considered “true” species, i.e., species that actually exist in an aqueous solution (e.g., Na+ and Cl- for NaCl). However, there may be times when you want to have your system report the “apparent” species between your inlet and/or outlet ports of a flowsheet. To do this, you need to understand how to define a species in a given configuration file as “apparent”, which is a special component type in the thermo-properties configuration dictionary.
For more information on creating a thermo-properties configuration dictionary, see How to setup simple chemistry.
What you need to update in the thermo-properties configuration dictionary
Add the
"Apparent"and"StateIndex"objects under your import statementsSpecify certain species as
"Apparent"within its component definitionGive a list of “true” species it will dissociate into
Define a “state_components” argument in the config and specify
"StateIndex.true"
Example Configuration Dictionary
This is best understood by going through an example. In this case, we will consider
building off of the How to setup simple chemistry guide and add "NaCl" as
an "Apparent" species.
from pyomo.environ import units as pyunits
from idaes.core import AqueousPhase
# Add Apparent in this import statement
from idaes.core.components import Solvent, Cation, Anion, Apparent
import idaes.generic_models.properties.core.pure.Perrys as Perrys
from idaes.generic_models.properties.core.pure.ConstantProperties import Constant
from idaes.generic_models.properties.core.state_definitions import FTPx
from idaes.generic_models.properties.core.eos.ideal import Ideal
# Add the import for StateIndex
from idaes.generic_models.properties.core.generic.generic_property import StateIndex
# Configuration dictionary
thermo_config = {
"components": {
'H2O': {"type": Solvent,
# Define the methods used to calculate the following properties
"dens_mol_liq_comp": Perrys,
"enth_mol_liq_comp": Perrys,
"cp_mol_liq_comp": Perrys,
"entr_mol_liq_comp": Perrys,
# Parameter data is always associated with the methods defined above
"parameter_data": {
"mw": (18.0153, pyunits.g/pyunits.mol),
# Parameters here come from Perry's Handbook: p. 2-98
"dens_mol_liq_comp_coeff": {
'1': (5.459, pyunits.kmol*pyunits.m**-3),
'2': (0.30542, pyunits.dimensionless),
'3': (647.13, pyunits.K),
'4': (0.081, pyunits.dimensionless)},
"enth_mol_form_liq_comp_ref": (-285.830, pyunits.kJ/pyunits.mol),
"enth_mol_form_vap_comp_ref": (0, pyunits.kJ/pyunits.mol),
# Parameters here come Perry's Handbook: p. 2-174
"cp_mol_liq_comp_coeff": {
'1': (2.7637E5, pyunits.J/pyunits.kmol/pyunits.K),
'2': (-2.0901E3, pyunits.J/pyunits.kmol/pyunits.K**2),
'3': (8.125, pyunits.J/pyunits.kmol/pyunits.K**3),
'4': (-1.4116E-2, pyunits.J/pyunits.kmol/pyunits.K**4),
'5': (9.3701E-6, pyunits.J/pyunits.kmol/pyunits.K**5)},
"cp_mol_ig_comp_coeff": {
'A': (30.09200, pyunits.J/pyunits.mol/pyunits.K),
'B': (6.832514, pyunits.J*pyunits.mol**-1*pyunits.K**-1*pyunits.kiloK**-1),
'C': (6.793435, pyunits.J*pyunits.mol**-1*pyunits.K**-1*pyunits.kiloK**-2),
'D': (-2.534480, pyunits.J*pyunits.mol**-1*pyunits.K**-1*pyunits.kiloK**-3),
'E': (0.082139, pyunits.J*pyunits.mol**-1*pyunits.K**-1*pyunits.kiloK**2),
'F': (-250.8810, pyunits.kJ/pyunits.mol),
'G': (223.3967, pyunits.J/pyunits.mol/pyunits.K),
'H': (0, pyunits.kJ/pyunits.mol)},
"entr_mol_form_liq_comp_ref": (69.95, pyunits.J/pyunits.K/pyunits.mol)
# End parameter_data
}},
'H_+': {"type": Cation, "charge": 1,
# Define the methods used to calculate the following properties
"dens_mol_liq_comp": Constant,
"enth_mol_liq_comp": Constant,
"cp_mol_liq_comp": Constant,
"entr_mol_liq_comp": Constant,
# Parameter data is always associated with the methods defined above
"parameter_data": {
"mw": (1.00784, pyunits.g/pyunits.mol),
"dens_mol_liq_comp_coeff": (55, pyunits.kmol*pyunits.m**-3),
"enth_mol_form_liq_comp_ref": (0, pyunits.kJ/pyunits.mol),
"cp_mol_liq_comp_coeff": (75000, pyunits.J/pyunits.kmol/pyunits.K),
"entr_mol_form_liq_comp_ref": (0, pyunits.J/pyunits.K/pyunits.mol)
},
# End parameter_data
},
'OH_-': {"type": Anion, "charge": -1,
# Define the methods used to calculate the following properties
"dens_mol_liq_comp": Constant,
"enth_mol_liq_comp": Constant,
"cp_mol_liq_comp": Constant,
"entr_mol_liq_comp": Constant,
# Parameter data is always associated with the methods defined above
"parameter_data": {
"mw": (17.008, pyunits.g/pyunits.mol),
"dens_mol_liq_comp_coeff": (55, pyunits.kmol*pyunits.m**-3),
"enth_mol_form_liq_comp_ref": (-230.000, pyunits.kJ/pyunits.mol),
"cp_mol_liq_comp_coeff": (75000, pyunits.J/pyunits.kmol/pyunits.K),
"entr_mol_form_liq_comp_ref": (-10.75, pyunits.J/pyunits.K/pyunits.mol)
},
# End parameter_data
},
'Na_+': {"type": Cation, "charge": 1,
# Define the methods used to calculate the following properties
"dens_mol_liq_comp": Constant,
"enth_mol_liq_comp": Constant,
"cp_mol_liq_comp": Constant,
"entr_mol_liq_comp": Constant,
# Parameter data is always associated with the methods defined above
"parameter_data": {
"mw": (22.989769, pyunits.g/pyunits.mol),
"dens_mol_liq_comp_coeff": (55, pyunits.kmol*pyunits.m**-3),
"enth_mol_form_liq_comp_ref": (-240.1, pyunits.kJ/pyunits.mol),
"cp_mol_liq_comp_coeff": (75000, pyunits.J/pyunits.kmol/pyunits.K),
"entr_mol_form_liq_comp_ref": (59, pyunits.J/pyunits.K/pyunits.mol)
},
# End parameter_data
},
'Cl_-': {"type": Anion, "charge": -1,
# Define the methods used to calculate the following properties
"dens_mol_liq_comp": Constant,
"enth_mol_liq_comp": Constant,
"cp_mol_liq_comp": Constant,
"entr_mol_liq_comp": Constant,
# Parameter data is always associated with the methods defined above
"parameter_data": {
"mw": (35.453, pyunits.g/pyunits.mol),
"dens_mol_liq_comp_coeff": (55, pyunits.kmol*pyunits.m**-3),
"enth_mol_form_liq_comp_ref": (-167.2, pyunits.kJ/pyunits.mol),
"cp_mol_liq_comp_coeff": (75000, pyunits.J/pyunits.kmol/pyunits.K),
"entr_mol_form_liq_comp_ref": (56.5, pyunits.J/pyunits.K/pyunits.mol)
},
# End parameter_data
},
# This is how an Apparent species is defined in the configuration dictionary
# it requires the same parameter arguments as True species, but also needs
# a dictionary for "dissociation_species" that tells how much of each
# true species this Apparent species is formed from.
'NaCl': {"type": Apparent,
"dissociation_species": {"Na_+":1, "Cl_-":1},
# Define the methods used to calculate the following properties
"dens_mol_liq_comp": Constant,
"enth_mol_liq_comp": Constant,
"cp_mol_liq_comp": Constant,
"entr_mol_liq_comp": Constant,
# Parameter data is always associated with the methods defined above
"parameter_data": {
"dens_mol_liq_comp_coeff": (55, pyunits.kmol*pyunits.m**-3),
"enth_mol_form_liq_comp_ref": (-945.53, pyunits.kJ/pyunits.mol),
"cp_mol_liq_comp_coeff": (167039, pyunits.J/pyunits.kmol/pyunits.K),
"entr_mol_form_liq_comp_ref": (100, pyunits.J/pyunits.K/pyunits.mol)
},
# End parameter_data
},
},
# End Component list
"phases": {'Liq': {"type": AqueousPhase,
"equation_of_state": Ideal},
},
"state_definition": FTPx,
"state_bounds": {"flow_mol": (0, 50, 100),
"temperature": (273.15, 300, 650),
"pressure": (5e4, 1e5, 1e6)
},
# We must define the 'StateIndex' as "true". This is because in ProteusLib,
# all speciation reactions are defined on the true species, not the
# apparent species.
"state_components": StateIndex.true,
"pressure_ref": 1e5,
"temperature_ref": 300,
"base_units": {"time": pyunits.s,
"length": pyunits.m,
"mass": pyunits.kg,
"amount": pyunits.mol,
"temperature": pyunits.K},
}
# End thermo_config definition
Note
When you define a species as "Apparent" and specify "state_components": StateIndex.true,
you cannot reference that species as part of your inlet variables or in any
reactions in the system. The "StateIndex" is used to define what species
can be used in reactions or in the inlet ports to set initial states. For ProteusLib,
we will always define reactions on a true species basis.