###############################################################################
# WaterTAP Copyright (c) 2021, The Regents of the University of California,
# through Lawrence Berkeley National Laboratory, Oak Ridge National
# Laboratory, National Renewable Energy Laboratory, and National Energy
# Technology Laboratory (subject to receipt of any required approvals from
# the U.S. Dept. of Energy). All rights reserved.
#
# Please see the files COPYRIGHT.md and LICENSE.md for full copyright and license
# information, respectively. These files are also available online at the URL
# "https://github.com/watertap-org/watertap/"
#
###############################################################################
# Import Pyomo libraries
from pyomo.common.config import ConfigBlock, ConfigValue, In
from pyomo.environ import (
Block,
Var,
Suffix,
NonNegativeReals,
Reals,
value,
units as pyunits,
)
# Import IDAES cores
import idaes.logger as idaeslog
from idaes.core import (
ControlVolume0DBlock,
declare_process_block_class,
MaterialBalanceType,
EnergyBalanceType,
MomentumBalanceType,
UnitModelBlockData,
useDefault,
)
from idaes.core.solvers import get_solver
from idaes.core.util.config import is_physical_parameter_block
from idaes.core.util.exceptions import ConfigurationError
from idaes.core.util.initialization import revert_state_vars
from idaes.core.util.tables import create_stream_table_dataframe
import idaes.core.util.scaling as iscale
from idaes.core.util.model_statistics import degrees_of_freedom
_log = idaeslog.getLogger(__name__)
[docs]@declare_process_block_class("PressureExchanger")
class PressureExchangerData(UnitModelBlockData):
"""
Standard Pressure Exchanger Unit Model Class:
- steady state only
"""
CONFIG = ConfigBlock()
CONFIG.declare(
"dynamic",
ConfigValue(
domain=In([False]),
default=False,
description="Dynamic model flag - must be False",
doc="""Indicates whether this model will be dynamic or not,
**default** = False. Pressure exchangers do not support dynamic behavior.""",
),
)
CONFIG.declare(
"has_holdup",
ConfigValue(
default=False,
domain=In([False]),
description="Holdup construction flag - must be False",
doc="""Indicates whether holdup terms should be constructed or not.
**default** - False. Pressure exchangers do not have defined volume, thus
this must be False.""",
),
)
CONFIG.declare(
"material_balance_type",
ConfigValue(
default=MaterialBalanceType.useDefault,
domain=In(MaterialBalanceType),
description="Material balance construction flag",
doc="""Indicates what type of mass balance should be constructed,
**default** - MaterialBalanceType.useDefault.
**Valid values:** {
**MaterialBalanceType.useDefault - refer to property package for default
balance type
**MaterialBalanceType.none** - exclude material balances,
**MaterialBalanceType.componentPhase** - use phase component balances,
**MaterialBalanceType.componentTotal** - use total component balances,
**MaterialBalanceType.elementTotal** - use total element balances,
**MaterialBalanceType.total** - use total material balance.}""",
),
)
CONFIG.declare(
"energy_balance_type",
ConfigValue(
default=EnergyBalanceType.useDefault,
domain=In(EnergyBalanceType),
description="Energy balance construction flag",
doc="""Indicates what type of energy balance should be constructed,
**default** - EnergyBalanceType.useDefault.
**Valid values:** {
**EnergyBalanceType.useDefault - refer to property package for default
balance type
**EnergyBalanceType.none** - exclude energy balances,
**EnergyBalanceType.enthalpyTotal** - single enthalpy balance for material,
**EnergyBalanceType.enthalpyPhase** - enthalpy balances for each phase,
**EnergyBalanceType.energyTotal** - single energy balance for material,
**EnergyBalanceType.energyPhase** - energy balances for each phase.}""",
),
)
CONFIG.declare(
"momentum_balance_type",
ConfigValue(
default=MomentumBalanceType.pressureTotal,
domain=In(MomentumBalanceType),
description="Momentum balance construction flag",
doc="""Indicates what type of momentum balance should be constructed,
**default** - MomentumBalanceType.pressureTotal.
**Valid values:** {
**MomentumBalanceType.none** - exclude momentum balances,
**MomentumBalanceType.pressureTotal** - single pressure balance for material,
**MomentumBalanceType.pressurePhase** - pressure balances for each phase,
**MomentumBalanceType.momentumTotal** - single momentum balance for material,
**MomentumBalanceType.momentumPhase** - momentum balances for each phase.}""",
),
)
CONFIG.declare(
"property_package",
ConfigValue(
default=useDefault,
domain=is_physical_parameter_block,
description="Property package to use for control volume",
doc="""Property parameter object used to define property calculations,
**default** - useDefault.
**Valid values:** {
**useDefault** - use default package from parent model or flowsheet,
**PhysicalParameterObject** - a PhysicalParameterBlock object.}""",
),
)
CONFIG.declare(
"property_package_args",
ConfigBlock(
implicit=True,
description="Arguments to use for constructing property packages",
doc="""A ConfigBlock with arguments to be passed to a property block(s)
and used when constructing these,
**default** - None.
**Valid values:** {
see property package for documentation.}""",
),
)
CONFIG.declare(
"has_mass_transfer",
ConfigValue(
default=False,
domain=In([True, False]),
description="Defines if there is mass transport between high- and low-pressure sides",
doc="""Indicates whether pressure exchanger solution mass transfer terms should be constructed or not.
**default** - False.""",
),
)
[docs] def build(self):
super().build()
# Pressure exchanger supports only liquid phase
if self.config.property_package.phase_list != ["Liq"]:
raise ConfigurationError(
"Pressure exchanger model only supports one liquid phase ['Liq'],"
"the property package has specified the following phases {}".format(
self.config.property_package.phase_list
)
)
self.scaling_factor = Suffix(direction=Suffix.EXPORT)
units_meta = self.config.property_package.get_metadata().get_derived_units
self.efficiency_pressure_exchanger = Var(
self.flowsheet().config.time,
initialize=0.95,
bounds=(1e-6, 1),
domain=NonNegativeReals,
units=pyunits.dimensionless,
doc="Pressure exchanger efficiency",
)
if self.config.has_mass_transfer:
self.mass_transfer_fraction_comp = Var(
self.flowsheet().config.time,
self.config.property_package.component_list,
initialize=0.05,
bounds=(1e-6, 1),
domain=NonNegativeReals,
units=pyunits.dimensionless,
doc="The fraction of solution transfering from high to low pressure side",
)
# Build control volume for high pressure side
self.high_pressure_side = ControlVolume0DBlock(
dynamic=False,
has_holdup=False,
property_package=self.config.property_package,
property_package_args=self.config.property_package_args,
)
self.high_pressure_side.add_state_blocks(has_phase_equilibrium=False)
self.high_pressure_side.add_material_balances(
balance_type=self.config.material_balance_type,
has_mass_transfer=self.config.has_mass_transfer,
)
self.high_pressure_side.add_momentum_balances(
balance_type=self.config.momentum_balance_type, has_pressure_change=True
)
@self.high_pressure_side.Expression(
self.flowsheet().config.time,
doc="Work transferred to high pressure side fluid (should be negative)",
)
def work(b, t):
return b.properties_in[t].flow_vol * b.deltaP[t]
# Build control volume for low pressure side
self.low_pressure_side = ControlVolume0DBlock(
dynamic=False,
has_holdup=False,
property_package=self.config.property_package,
property_package_args=self.config.property_package_args,
)
self.low_pressure_side.add_state_blocks(has_phase_equilibrium=False)
self.low_pressure_side.add_material_balances(
balance_type=self.config.material_balance_type,
has_mass_transfer=self.config.has_mass_transfer,
)
self.low_pressure_side.add_momentum_balances(
balance_type=self.config.momentum_balance_type, has_pressure_change=True
)
@self.low_pressure_side.Expression(
self.flowsheet().config.time,
doc="Work transferred to low pressure side fluid",
)
def work(b, t):
return b.properties_in[t].flow_vol * b.deltaP[t]
# Add Ports
self.add_inlet_port(name="high_pressure_inlet", block=self.high_pressure_side)
self.add_outlet_port(name="high_pressure_outlet", block=self.high_pressure_side)
self.add_inlet_port(name="low_pressure_inlet", block=self.low_pressure_side)
self.add_outlet_port(name="low_pressure_outlet", block=self.low_pressure_side)
# Performance equations
@self.Constraint(self.flowsheet().config.time, doc="Pressure transfer")
def eq_pressure_transfer(b, t):
return (
b.low_pressure_side.deltaP[t]
== b.efficiency_pressure_exchanger[t] * -b.high_pressure_side.deltaP[t]
)
@self.Constraint(self.flowsheet().config.time, doc="Equal volumetric flow rate")
def eq_equal_flow_vol(b, t):
return (
b.high_pressure_side.properties_out[t].flow_vol
== b.low_pressure_side.properties_in[t].flow_vol
)
@self.Constraint(
self.flowsheet().config.time, doc="Equal low pressure on both sides"
)
def eq_equal_low_pressure(b, t):
return (
b.high_pressure_side.properties_out[t].pressure
== b.low_pressure_side.properties_in[t].pressure
)
@self.low_pressure_side.Constraint(
self.flowsheet().config.time, doc="Isothermal constraint"
)
def eq_isothermal_temperature(b, t):
return b.properties_in[t].temperature == b.properties_out[t].temperature
@self.high_pressure_side.Constraint(
self.flowsheet().config.time, doc="Isothermal constraint"
)
def eq_isothermal_temperature(b, t):
return b.properties_in[t].temperature == b.properties_out[t].temperature
if self.config.has_mass_transfer:
@self.Constraint(
self.flowsheet().config.time,
self.config.property_package.phase_list,
self.config.property_package.component_list,
doc="Mass transfer from high pressure side",
)
def eq_mass_transfer_from_high_pressure_side(b, t, p, j):
comp = self.config.property_package.get_component(j)
return b.high_pressure_side.mass_transfer_term[
t, p, j
] == -b.mass_transfer_fraction_comp[
t, j
] * b.high_pressure_side.properties_in[
t
].get_material_flow_terms(
p, j
)
@self.Constraint(
self.flowsheet().config.time,
self.config.property_package.phase_list,
self.config.property_package.component_list,
doc="Mass transfer term",
)
def eq_mass_transfer_term(b, t, p, j):
return (
b.high_pressure_side.mass_transfer_term[t, p, j]
== -b.low_pressure_side.mass_transfer_term[t, p, j]
)
[docs] def initialize_build(
self,
state_args=None,
routine=None,
outlvl=idaeslog.NOTSET,
solver=None,
optarg=None,
):
"""
General wrapper for pressure exchanger initialization routine
Keyword Arguments:
routine : str stating which initialization routine to execute
* None - currently no specialized routine for Pressure exchanger unit
state_args : a dict of arguments to be passed to the property
package(s) to provide an initial state for
initialization (see documentation of the specific
property package) (default = {}).
outlvl : sets output level of initialization routine (default=idaeslog.NOTSET)
optarg : solver options dictionary object, if None provided an empty
dictionary will be used (default=None)
solver : solver object or string indicating which solver to use during
initialization, if None provided the default solver will be used
(default = None)
Returns: None
"""
# Get loggers
init_log = idaeslog.getInitLogger(self.name, outlvl, tag="properties")
solve_log = idaeslog.getSolveLogger(self.name, outlvl, tag="properties")
# Set solver and options
opt = get_solver(solver, optarg)
# initialize inlets
flags_low_in = self.low_pressure_side.properties_in.initialize(
outlvl=outlvl,
optarg=optarg,
solver=solver,
state_args=state_args,
hold_state=True,
)
flags_high_in = self.high_pressure_side.properties_in.initialize(
outlvl=outlvl,
optarg=optarg,
solver=solver,
state_args=state_args,
hold_state=True,
)
init_log.info_high("Initialize inlets complete")
# check that inlets are feasible
if value(self.low_pressure_side.properties_in[0].pressure) > value(
self.high_pressure_side.properties_in[0].pressure
):
raise ConfigurationError(
"Initializing pressure exchanger failed because "
"the low pressure side inlet has a higher pressure "
"than the high pressure side inlet"
)
# only needed when there is no mass trnasfer
if (
abs(
value(self.low_pressure_side.properties_in[0].flow_vol)
- value(self.high_pressure_side.properties_in[0].flow_vol)
)
/ value(self.high_pressure_side.properties_in[0].flow_vol)
> 1e-4
and not self.config.has_mass_transfer
): # flow_vol values are not within 0.1%
raise ConfigurationError(
"Initializing pressure exchanger failed because "
"the volumetric flow rates are not equal for both inlets "
+ str(value(self.high_pressure_side.properties_out[0].flow_vol))
+ ","
+ str(value(self.low_pressure_side.properties_in[0].flow_vol))
)
else: # volumetric flow is equal, deactivate flow constraint for the solve
self.eq_equal_flow_vol.deactivate()
# initialize outlets from inlets and update pressure
def propogate_state(sb1, sb2):
state_dict_1 = sb1.define_state_vars()
state_dict_2 = sb2.define_state_vars()
for k in state_dict_1.keys():
if state_dict_1[k].is_indexed():
for m in state_dict_1[k].keys():
state_dict_2[k][m].value = state_dict_1[k][m].value
else:
state_dict_2[k].value = state_dict_1[k].value
# low pressure side
propogate_state(
self.low_pressure_side.properties_in[0],
self.low_pressure_side.properties_out[0],
)
self.low_pressure_side.properties_out[
0
].pressure = self.low_pressure_side.properties_in[
0
].pressure.value + self.efficiency_pressure_exchanger[
0
].value * (
self.high_pressure_side.properties_in[0].pressure.value
- self.low_pressure_side.properties_in[0].pressure.value
)
# high pressure side
propogate_state(
self.high_pressure_side.properties_in[0],
self.high_pressure_side.properties_out[0],
)
self.high_pressure_side.properties_out[
0
].pressure.value = self.low_pressure_side.properties_in[0].pressure.value
init_log.info_high("Initialize outlets complete")
# Solve unit
with idaeslog.solver_log(solve_log, idaeslog.DEBUG) as slc:
res = opt.solve(self, tee=slc.tee)
init_log.info("Initialization complete: {}".format(idaeslog.condition(res)))
# release state of fixed variables
self.low_pressure_side.properties_in.release_state(flags_low_in)
self.high_pressure_side.properties_in.release_state(flags_high_in)
# reactivate volumetric flow constraint
self.eq_equal_flow_vol.activate()
def calculate_scaling_factors(self):
super().calculate_scaling_factors()
# scale variables
if iscale.get_scaling_factor(self.efficiency_pressure_exchanger) is None:
# efficiency should always be between 0.1-1
iscale.set_scaling_factor(self.efficiency_pressure_exchanger, 1)
if hasattr(self, "mass_transfer_fraction_comp"):
if iscale.get_scaling_factor(self.mass_transfer_fraction_comp) is None:
iscale.set_scaling_factor(self.mass_transfer_fraction_comp, 1)
# scale expressions
if iscale.get_scaling_factor(self.low_pressure_side.work) is None:
sf = iscale.get_scaling_factor(
self.low_pressure_side.properties_in[0].flow_vol
)
sf = sf * iscale.get_scaling_factor(self.low_pressure_side.deltaP[0])
iscale.set_scaling_factor(self.low_pressure_side.work, sf)
if iscale.get_scaling_factor(self.high_pressure_side.work) is None:
sf = iscale.get_scaling_factor(
self.high_pressure_side.properties_in[0].flow_vol
)
sf = sf * iscale.get_scaling_factor(self.high_pressure_side.deltaP[0])
iscale.set_scaling_factor(self.high_pressure_side.work, sf)
# transform constraints
for t, c in self.low_pressure_side.eq_isothermal_temperature.items():
sf = iscale.get_scaling_factor(
self.low_pressure_side.properties_in[t].temperature
)
iscale.constraint_scaling_transform(c, sf)
for t, c in self.high_pressure_side.eq_isothermal_temperature.items():
sf = iscale.get_scaling_factor(
self.high_pressure_side.properties_in[t].temperature
)
iscale.constraint_scaling_transform(c, sf)
for t, c in self.eq_pressure_transfer.items():
sf = iscale.get_scaling_factor(self.low_pressure_side.deltaP[t])
iscale.constraint_scaling_transform(c, sf)
for t, c in self.eq_equal_flow_vol.items():
sf = iscale.get_scaling_factor(
self.low_pressure_side.properties_in[t].flow_vol
)
iscale.constraint_scaling_transform(c, sf)
for t, c in self.eq_equal_low_pressure.items():
sf = iscale.get_scaling_factor(
self.low_pressure_side.properties_in[t].pressure
)
iscale.constraint_scaling_transform(c, sf)
if hasattr(self, "eq_mass_transfer_from_high_pressure_side"):
for (t, p, j), c in self.eq_mass_transfer_from_high_pressure_side.items():
sf = iscale.get_scaling_factor(
self.high_pressure_side.properties_in[t].get_material_flow_terms(
p, j
)
)
iscale.constraint_scaling_transform(c, sf)
if hasattr(self, "eq_mass_transfer_term"):
for (t, p, j), c in self.eq_mass_transfer_term.items():
sf = iscale.get_scaling_factor(
self.high_pressure_side.mass_transfer_term[t, p, j]
)
iscale.constraint_scaling_transform(c, sf)
sf = iscale.get_scaling_factor(
self.low_pressure_side.mass_transfer_term[t, p, j]
)
iscale.constraint_scaling_transform(c, sf)
def _get_stream_table_contents(self, time_point=0):
return create_stream_table_dataframe(
{
"HP Side In": self.high_pressure_inlet,
"HP Side Out": self.high_pressure_outlet,
"LP Side In": self.low_pressure_inlet,
"LP Side Out": self.low_pressure_outlet,
},
time_point=time_point,
)
def _get_performance_contents(self, time_point=0):
t = time_point
return {
"vars": {
"Efficiency": self.efficiency_pressure_exchanger[t],
"HP Side Pressure Change": self.high_pressure_side.deltaP[t],
"LP Side Pressure Change": self.low_pressure_side.deltaP[t],
},
"exprs": {
"HP Side Mechanical Work": self.high_pressure_side.work[t],
"LP Side Mechanical Work": self.low_pressure_side.work[t],
},
"params": {},
}