#################################################################################
# The Institute for the Design of Advanced Energy Systems Integrated Platform
# Framework (IDAES IP) was produced under the DOE Institute for the
# Design of Advanced Energy Systems (IDAES), and is copyright (c) 2018-2021
# by the software owners: The Regents of the University of California, through
# Lawrence Berkeley National Laboratory, National Technology & Engineering
# Solutions of Sandia, LLC, Carnegie Mellon University, West Virginia University
# Research Corporation, et al. All rights reserved.
#
# Please see the files COPYRIGHT.md and LICENSE.md for full copyright and
# license information.
#################################################################################
"""
IDAES heat exchanger model using effectiveness-NTU method
Assumptions:
* No phase equilibrium or reactions occur within unit
"""
# Import Pyomo libraries
from pyomo.environ import (Block,
Constraint,
Expression,
Param,
PositiveReals,
Reference,
units as pyunits,
Var)
from pyomo.common.config import Bool, ConfigBlock, ConfigValue, In
# Import IDAES cores
from idaes.core import (ControlVolume0DBlock,
declare_process_block_class,
MaterialBalanceType,
EnergyBalanceType,
MomentumBalanceType,
UnitModelBlockData,
useDefault)
from idaes.core.util.config import is_physical_parameter_block
from idaes.core.util.tables import create_stream_table_dataframe
from idaes.core.util.math import smooth_min, smooth_max
from idaes.core.util import get_solver
import idaes.core.util.unit_costing as costing
import idaes.logger as idaeslog
__author__ = "Paul Akula, Andrew Lee"
# Set up logger
_log = idaeslog.getLogger(__name__)
[docs]@declare_process_block_class("HeatExchangerNTU")
class HeatExchangerNTUData(UnitModelBlockData):
"""Heat Exchanger Unit Model using NTU method."""
CONFIG = UnitModelBlockData.CONFIG()
# Configuration template for fluid specific arguments
_SideCONFIG = ConfigBlock()
_SideCONFIG.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.}"""))
_SideCONFIG.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.}"""))
_SideCONFIG.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.}"""))
_SideCONFIG.declare("has_pressure_change", ConfigValue(
default=False,
domain=Bool,
description="Pressure change term construction flag",
doc="""Indicates whether terms for pressure change should be
constructed,
**default** - False.
**Valid values:** {
**True** - include pressure change terms,
**False** - exclude pressure change terms.}"""))
_SideCONFIG.declare("property_package", ConfigValue(
default=useDefault,
domain=is_physical_parameter_block,
description="Property package to use ",
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.}"""))
_SideCONFIG.declare("property_package_args", ConfigBlock(
implicit=True,
description="Arguments to use for constructing property package",
doc="""A ConfigBlock with arguments to be passed to
property block(s) and used when constructing these,
**default** - None.
**Valid values:** {
see property package for documentation.}"""))
# Create individual config blocks for hot and cold sides
CONFIG.declare("hot_side",
_SideCONFIG(doc="Hot fluid config arguments"))
CONFIG.declare("cold_side",
_SideCONFIG(doc="Cold fluid config arguments"))
[docs] def build(self):
# Call UnitModel.build to setup model
super().build()
# ---------------------------------------------------------------------
# Build hot-side control volume
self.hot_side = ControlVolume0DBlock(default={
"dynamic": self.config.dynamic,
"has_holdup": self.config.has_holdup,
"property_package": self.config.hot_side.property_package,
"property_package_args":
self.config.hot_side.property_package_args})
# TODO : Add support for phase equilibrium?
self.hot_side.add_state_blocks(has_phase_equilibrium=False)
self.hot_side.add_material_balances(
balance_type=self.config.hot_side.material_balance_type,
has_phase_equilibrium=False)
self.hot_side.add_energy_balances(
balance_type=self.config.hot_side.energy_balance_type,
has_heat_transfer=True)
self.hot_side.add_momentum_balances(
balance_type=self.config.hot_side.momentum_balance_type,
has_pressure_change=self.config.hot_side.has_pressure_change)
# ---------------------------------------------------------------------
# Build cold-side control volume
self.cold_side = ControlVolume0DBlock(default={
"dynamic": self.config.dynamic,
"has_holdup": self.config.has_holdup,
"property_package": self.config.cold_side.property_package,
"property_package_args":
self.config.cold_side.property_package_args})
self.cold_side.add_state_blocks(has_phase_equilibrium=False)
self.cold_side.add_material_balances(
balance_type=self.config.cold_side.material_balance_type,
has_phase_equilibrium=False)
self.cold_side.add_energy_balances(
balance_type=self.config.cold_side.energy_balance_type,
has_heat_transfer=True)
self.cold_side.add_momentum_balances(
balance_type=self.config.cold_side.momentum_balance_type,
has_pressure_change=self.config.cold_side.has_pressure_change)
# ---------------------------------------------------------------------
# Add Ports to control volumes
self.add_inlet_port(name="hot_inlet",
block=self.hot_side,
doc='Hot side inlet port')
self.add_outlet_port(name="hot_outlet",
block=self.hot_side,
doc='Hot side outlet port')
self.add_inlet_port(name="cold_inlet",
block=self.cold_side,
doc='Cold side inlet port')
self.add_outlet_port(name="cold_outlet",
block=self.cold_side,
doc='Cold side outlet port')
# ---------------------------------------------------------------------
# Add unit level References
# Set references to balance terms at unit level
self.heat_duty = Reference(self.cold_side.heat[:])
# ---------------------------------------------------------------------
# Add performance equations
# All units of measurement will be based on hot side
hunits = self.config.hot_side.property_package.get_metadata(
).get_derived_units
# Common heat exchanger variables
self.area = Var(
initialize=1,
units=hunits("area"),
domain=PositiveReals,
doc="Heat transfer area")
self.heat_transfer_coefficient = Var(
self.flowsheet().time,
initialize=1,
units=hunits("heat_transfer_coefficient"),
domain=PositiveReals,
doc="Overall heat transfer coefficient")
# Overall energy balance
def rule_energy_balance(blk, t):
return blk.hot_side.heat[t] == -pyunits.convert(
blk.cold_side.heat[t], to_units=hunits("power"))
self.energy_balance_constraint = Constraint(
self.flowsheet().time, rule=rule_energy_balance)
# Add e-NTU variables
self.effectiveness = Var(
self.flowsheet().time,
initialize=1,
units=pyunits.dimensionless,
domain=PositiveReals,
doc="Effectiveness factor for NTU method")
# Minimum heat capacitance ratio for e-NTU method
self.eps_cmin = Param(initialize=1e-3,
mutable=True,
units=hunits("power")/hunits("temperature"),
doc="Epsilon parameter for smooth Cmin and Cmax")
# TODO : Support both mass and mole based flows
def rule_Cmin(blk, t):
caph = (blk.hot_side.properties_in[t].flow_mol *
blk.hot_side.properties_in[t].cp_mol)
capc = pyunits.convert(
blk.cold_side.properties_in[t].flow_mol *
blk.cold_side.properties_in[t].cp_mol,
to_units=hunits("power")/hunits("temperature"))
return smooth_min(caph, capc, eps=blk.eps_cmin)
self.Cmin = Expression(self.flowsheet().time,
rule=rule_Cmin,
doc='Minimum heat capacitance rate')
def rule_Cmax(blk, t):
caph = (blk.hot_side.properties_in[t].flow_mol *
blk.hot_side.properties_in[t].cp_mol)
capc = pyunits.convert(
blk.cold_side.properties_in[t].flow_mol *
blk.cold_side.properties_in[t].cp_mol,
to_units=hunits("power")/hunits("temperature"))
return smooth_max(caph, capc, eps=blk.eps_cmin)
self.Cmax = Expression(self.flowsheet().time,
rule=rule_Cmax,
doc='Maximum heat capacitance rate')
# Heat capacitance ratio
def rule_Cratio(blk, t):
return blk.Cmin[t] / blk.Cmax[t]
self.Cratio = Expression(self.flowsheet().time,
rule=rule_Cratio,
doc='Heat capacitance ratio')
def rule_NTU(blk, t):
return blk.heat_transfer_coefficient[t]*blk.area/blk.Cmin[t]
self.NTU = Expression(self.flowsheet().time,
rule=rule_NTU,
doc='Number of heat transfer units')
# Heat transfer by e-NTU method
def rule_entu(blk, t):
return blk.hot_side.heat[t] == -(
blk.effectiveness[t] *
blk.Cmin[t] *
(blk.hot_side.properties_in[t].temperature -
pyunits.convert(blk.cold_side.properties_in[t].temperature,
to_units=hunits("temperature"))))
self.heat_duty_constraint = Constraint(
self.flowsheet().time,
rule=rule_entu)
# TODO : Add scaling methods
[docs] def initialize(
self,
hot_side_state_args=None,
cold_side_state_args=None,
outlvl=idaeslog.NOTSET,
solver=None,
optarg=None,
duty=None,
):
"""
Heat exchanger initialization method.
Args:
hot_side_state_args : a dict of arguments to be passed to the
property initialization for the hot side (see documentation of
the specific property package) (default = None).
cold_side_state_args : a dict of arguments to be passed to the
property initialization for the cold side (see documentation of
the specific property package) (default = None).
outlvl : sets output level of initialization routine
optarg : solver options dictionary object (default=None, use
default solver options)
solver : str indicating which solver to use during
initialization (default = None, use default solver)
duty : an initial guess for the amount of heat transfered. This
should be a tuple in the form (value, units), (default
= (1000 J/s))
Returns:
None
"""
# Set solver options
init_log = idaeslog.getInitLogger(self.name, outlvl, tag="unit")
solve_log = idaeslog.getSolveLogger(self.name, outlvl, tag="unit")
hot_side = self.hot_side
cold_side = self.cold_side
# Create solver
opt = get_solver(solver, optarg)
flags1 = hot_side.initialize(
outlvl=outlvl, optarg=optarg, solver=solver,
state_args=hot_side_state_args
)
init_log.info_high("Initialization Step 1a (hot side) Complete.")
flags2 = cold_side.initialize(
outlvl=outlvl, optarg=optarg, solver=solver,
state_args=cold_side_state_args
)
init_log.info_high("Initialization Step 1b (cold side) Complete.")
# ---------------------------------------------------------------------
# Solve unit without heat transfer equation
# if costing block exists, deactivate
if hasattr(self, "costing"):
self.costing.deactivate()
self.energy_balance_constraint.deactivate()
# Get side 1 and side 2 heat units, and convert duty as needed
s1_units = hot_side.heat.get_units()
s2_units = cold_side.heat.get_units()
if duty is None:
# Assume 1000 J/s and check for unitless properties
if s1_units is None and s2_units is None:
# Backwards compatability for unitless properties
s1_duty = - 1000
s2_duty = 1000
else:
s1_duty = pyunits.convert_value(-1000,
from_units=pyunits.W,
to_units=s1_units)
s2_duty = pyunits.convert_value(1000,
from_units=pyunits.W,
to_units=s2_units)
else:
# Duty provided with explicit units
s1_duty = -pyunits.convert_value(duty[0],
from_units=duty[1],
to_units=s1_units)
s2_duty = pyunits.convert_value(duty[0],
from_units=duty[1],
to_units=s2_units)
cold_side.heat.fix(s2_duty)
for i in hot_side.heat:
hot_side.heat[i].value = s1_duty
with idaeslog.solver_log(solve_log, idaeslog.DEBUG) as slc:
res = opt.solve(self, tee=slc.tee)
init_log.info_high("Initialization Step 2 {}.".format(
idaeslog.condition(res)))
cold_side.heat.unfix()
self.energy_balance_constraint.activate()
# ---------------------------------------------------------------------
# Solve unit
with idaeslog.solver_log(solve_log, idaeslog.DEBUG) as slc:
res = opt.solve(self, tee=slc.tee)
init_log.info_high("Initialization Step 3 {}.".format(
idaeslog.condition(res)))
# ---------------------------------------------------------------------
# Release Inlet state
hot_side.release_state(flags1, outlvl=outlvl)
cold_side.release_state(flags2, outlvl=outlvl)
init_log.info("Initialization Completed, {}".format(
idaeslog.condition(res)))
# if costing block exists, activate and initialize
if hasattr(self, "costing"):
self.costing.activate()
costing.initialize(self.costing)
def _get_stream_table_contents(self, time_point=0):
return create_stream_table_dataframe(
{
"Hot Inlet": self.hot_inlet,
"Hot Outlet": self.hot_outlet,
"Cold Inlet": self.cold_inlet,
"Cold Outlet": self.cold_outlet,
},
time_point=time_point,
)
def get_costing(self, module=costing, year=None, **kwargs):
if not hasattr(self.flowsheet(), "costing"):
self.flowsheet().get_costing(year=year)
self.costing = Block()
module.hx_costing(self.costing, **kwargs)