def build(self):
"""
Building model
Args:
None
Returns:
None
"""
########################################################################
# Call UnitModel.build to setup dynamics and configure #
########################################################################
super().build()
self._process_config()
config = self.config
########################################################################
# Add control volumes #
########################################################################
hot_side = _make_heater_control_volume(
self,
config.hot_side_name,
config.hot_side_config,
dynamic=config.dynamic,
has_holdup=config.has_holdup,
)
cold_side = _make_heater_control_volume(
self,
config.cold_side_name,
config.cold_side_config,
dynamic=config.dynamic,
has_holdup=config.has_holdup,
)
# Add references to the hot side and cold side, so that we have solid
# names to refer to internally. side_1 and side_2 also maintain
# compatability with older models. Using add_object_reference keeps
# these from showing up when you iterate through pyomo compoents in a
# model, so only the user specified control volume names are "seen"
if not hasattr(self, "side_1"):
add_object_reference(self, "side_1", hot_side)
if not hasattr(self, "side_2"):
add_object_reference(self, "side_2", cold_side)
if not hasattr(self, "hot_side"):
add_object_reference(self, "hot_side", hot_side)
if not hasattr(self, "cold_side"):
add_object_reference(self, "cold_side", cold_side)
########################################################################
# Add variables #
########################################################################
# Use hot side units as basis
s1_metadata = config.hot_side_config.property_package.get_metadata()
q_units = s1_metadata.get_derived_units("power")
u_units = s1_metadata.get_derived_units("heat_transfer_coefficient")
a_units = s1_metadata.get_derived_units("area")
temp_units = s1_metadata.get_derived_units("temperature")
u = self.overall_heat_transfer_coefficient = Var(
self.flowsheet().config.time,
domain=PositiveReals,
initialize=100.0,
doc="Overall heat transfer coefficient",
units=u_units)
a = self.area = Var(domain=PositiveReals,
initialize=1000.0,
doc="Heat exchange area",
units=a_units)
self.delta_temperature_in = Var(
self.flowsheet().config.time,
initialize=10.0,
doc="Temperature difference at the hot inlet end",
units=temp_units)
self.delta_temperature_out = Var(
self.flowsheet().config.time,
initialize=10.1,
doc="Temperature difference at the hot outlet end",
units=temp_units)
if self.config.flow_pattern == HeatExchangerFlowPattern.crossflow:
self.crossflow_factor = Var(
self.flowsheet().config.time,
initialize=1.0,
doc="Factor to adjust coutercurrent flow heat "
"transfer calculation for cross flow.",
)
f = self.crossflow_factor
self.heat_duty = Reference(cold_side.heat)
########################################################################
# Add ports #
########################################################################
i1 = self.add_inlet_port(name=f"{config.hot_side_name}_inlet",
block=hot_side,
doc="Hot side inlet")
i2 = self.add_inlet_port(name=f"{config.cold_side_name}_inlet",
block=cold_side,
doc="Cold side inlet")
o1 = self.add_outlet_port(name=f"{config.hot_side_name}_outlet",
block=hot_side,
doc="Hot side outlet")
o2 = self.add_outlet_port(name=f"{config.cold_side_name}_outlet",
block=cold_side,
doc="Cold side outlet")
# Using Andrew's function for now. I want these port names for backward
# compatablity, but I don't want them to appear if you iterate throught
# components and add_object_reference hides them from Pyomo.
if not hasattr(self, "inlet_1"):
add_object_reference(self, "inlet_1", i1)
if not hasattr(self, "inlet_2"):
add_object_reference(self, "inlet_2", i2)
if not hasattr(self, "outlet_1"):
add_object_reference(self, "outlet_1", o1)
if not hasattr(self, "outlet_2"):
add_object_reference(self, "outlet_2", o2)
if not hasattr(self, "hot_inlet"):
add_object_reference(self, "hot_inlet", i1)
if not hasattr(self, "cold_inlet"):
add_object_reference(self, "cold_inlet", i2)
if not hasattr(self, "hot_outlet"):
add_object_reference(self, "hot_outlet", o1)
if not hasattr(self, "cold_outlet"):
add_object_reference(self, "cold_outlet", o2)
########################################################################
# Add end temperature differnece constraints #
########################################################################
@self.Constraint(self.flowsheet().config.time)
def delta_temperature_in_equation(b, t):
if b.config.flow_pattern == HeatExchangerFlowPattern.cocurrent:
return (b.delta_temperature_in[t] ==
hot_side.properties_in[t].temperature -
pyunits.convert(cold_side.properties_in[t].temperature,
to_units=temp_units))
else:
return (
b.delta_temperature_in[t] ==
hot_side.properties_in[t].temperature -
pyunits.convert(cold_side.properties_out[t].temperature,
to_units=temp_units))
@self.Constraint(self.flowsheet().config.time)
def delta_temperature_out_equation(b, t):
if b.config.flow_pattern == HeatExchangerFlowPattern.cocurrent:
return (
b.delta_temperature_out[t] ==
hot_side.properties_out[t].temperature -
pyunits.convert(cold_side.properties_out[t].temperature,
to_units=temp_units))
else:
return (b.delta_temperature_out[t] ==
hot_side.properties_out[t].temperature -
pyunits.convert(cold_side.properties_in[t].temperature,
to_units=temp_units))
########################################################################
# Add a unit level energy balance #
########################################################################
@self.Constraint(self.flowsheet().config.time)
def unit_heat_balance(b, t):
return 0 == (hot_side.heat[t] +
pyunits.convert(cold_side.heat[t], to_units=q_units))
########################################################################
# Add delta T calculations using callack function, lots of options, #
# and users can provide their own if needed #
########################################################################
config.delta_temperature_callback(self)
########################################################################
# Add Heat transfer equation #
########################################################################
deltaT = self.delta_temperature
@self.Constraint(self.flowsheet().config.time)
def heat_transfer_equation(b, t):
if self.config.flow_pattern == HeatExchangerFlowPattern.crossflow:
return pyunits.convert(self.heat_duty[t],
to_units=q_units) == (f[t] * u[t] * a *
deltaT[t])
else:
return pyunits.convert(self.heat_duty[t],
to_units=q_units) == (u[t] * a *
deltaT[t])
########################################################################
# Add symbols for LaTeX equation rendering #
########################################################################
self.overall_heat_transfer_coefficient.latex_symbol = "U"
self.area.latex_symbol = "A"
hot_side.heat.latex_symbol = "Q_1"
cold_side.heat.latex_symbol = "Q_2"
self.delta_temperature.latex_symbol = "\\Delta T"
def build(self):
"""
Building model
Args:
None
Returns:
None
"""
########################################################################
# Call UnitModel.build to setup dynamics and configure #
########################################################################
super().build()
self._process_config()
config = self.config
time = self.flowsheet().config.time
########################################################################
# Add control volumes #
########################################################################
hot_side = _make_heater_control_volume(
self,
config.hot_side_name,
config.hot_side_config,
dynamic=config.dynamic,
has_holdup=config.has_holdup,
)
cold_side = _make_heater_control_volume(
self,
config.cold_side_name,
config.cold_side_config,
dynamic=config.dynamic,
has_holdup=config.has_holdup,
)
# Add refernces to the hot side and cold side, so that we have solid
# names to refere to internally. side_1 and side_2 also maintain
# compatability with older models. Using add_object_reference keeps
# these from showing up when you iterate through pyomo compoents in a
# model, so only the user specified control volume names are "seen"
if not hasattr(self, "side_1"):
add_object_reference(self, "side_1", hot_side)
if not hasattr(self, "side_2"):
add_object_reference(self, "side_2", cold_side)
if not hasattr(self, "hot_side"):
add_object_reference(self, "hot_side", hot_side)
if not hasattr(self, "cold_side"):
add_object_reference(self, "cold_side", cold_side)
########################################################################
# Add variables #
########################################################################
# Use hot side units as basis
s1_metadata = config.hot_side_config.property_package.get_metadata()
f_units = s1_metadata.get_derived_units("flow_mole")
cp_units = s1_metadata.get_derived_units("heat_capacity_mole")
q_units = s1_metadata.get_derived_units("power")
u_units = s1_metadata.get_derived_units("heat_transfer_coefficient")
a_units = s1_metadata.get_derived_units("area")
temp_units = s1_metadata.get_derived_units("temperature")
self.overall_heat_transfer_coefficient = pyo.Var(
time,
domain=pyo.PositiveReals,
initialize=100.0,
doc="Overall heat transfer coefficient",
units=u_units,
)
self.area = pyo.Var(
domain=pyo.PositiveReals,
initialize=1000.0,
doc="Heat exchange area",
units=a_units,
)
self.heat_duty = pyo.Reference(cold_side.heat)
########################################################################
# Add ports #
########################################################################
i1 = self.add_inlet_port(name=f"{config.hot_side_name}_inlet",
block=hot_side,
doc="Hot side inlet")
i2 = self.add_inlet_port(name=f"{config.cold_side_name}_inlet",
block=cold_side,
doc="Cold side inlet")
o1 = self.add_outlet_port(name=f"{config.hot_side_name}_outlet",
block=hot_side,
doc="Hot side outlet")
o2 = self.add_outlet_port(name=f"{config.cold_side_name}_outlet",
block=cold_side,
doc="Cold side outlet")
# Using Andrew's function for now. I want these port names for backward
# compatablity, but I don't want them to appear if you iterate throught
# components and add_object_reference hides them from Pyomo.
if not hasattr(self, "inlet_1"):
add_object_reference(self, "inlet_1", i1)
if not hasattr(self, "inlet_2"):
add_object_reference(self, "inlet_2", i2)
if not hasattr(self, "outlet_1"):
add_object_reference(self, "outlet_1", o1)
if not hasattr(self, "outlet_2"):
add_object_reference(self, "outlet_2", o2)
if not hasattr(self, "hot_inlet"):
add_object_reference(self, "hot_inlet", i1)
if not hasattr(self, "cold_inlet"):
add_object_reference(self, "cold_inlet", i2)
if not hasattr(self, "hot_outlet"):
add_object_reference(self, "hot_outlet", o1)
if not hasattr(self, "cold_outlet"):
add_object_reference(self, "cold_outlet", o2)
########################################################################
# Add a unit level energy balance #
########################################################################
@self.Constraint(time, doc="Heat balance equation")
def unit_heat_balance(b, t):
return 0 == (hot_side.heat[t] +
pyunits.convert(cold_side.heat[t], to_units=q_units))
########################################################################
# Add some useful expressions for condenser performance #
########################################################################
@self.Expression(time, doc="Inlet temperature difference")
def delta_temperature_in(b, t):
return (hot_side.properties_in[t].temperature - pyunits.convert(
cold_side.properties_in[t].temperature, temp_units))
@self.Expression(time, doc="Outlet temperature difference")
def delta_temperature_out(b, t):
return (hot_side.properties_out[t].temperature - pyunits.convert(
cold_side.properties_out[t].temperature, temp_units))
@self.Expression(time, doc="NTU Based temperature difference")
def delta_temperature_ntu(b, t):
return (hot_side.properties_in[t].temperature_sat -
pyunits.convert(cold_side.properties_in[t].temperature,
temp_units))
@self.Expression(
time,
doc="Minimum product of flow rate and heat "
"capacity (always on tube side since shell side has phase change)")
def mcp_min(b, t):
return pyunits.convert(
cold_side.properties_in[t].flow_mol *
cold_side.properties_in[t].cp_mol_phase['Liq'],
f_units * cp_units)
@self.Expression(time, doc="Number of transfer units (NTU)")
def ntu(b, t):
return b.overall_heat_transfer_coefficient[t] * b.area / b.mcp_min[
t]
@self.Expression(time, doc="Condenser effectiveness factor")
def effectiveness(b, t):
return 1 - pyo.exp(-self.ntu[t])
@self.Expression(time, doc="Heat treansfer")
def heat_transfer(b, t):
return b.effectiveness[t] * b.mcp_min[t] * b.delta_temperature_ntu[
t]
########################################################################
# Add Equations to calculate heat duty based on NTU method #
########################################################################
@self.Constraint(time,
doc="Heat transfer rate equation based on NTU method")
def heat_transfer_equation(b, t):
return (pyunits.convert(cold_side.heat[t],
q_units) == self.heat_transfer[t])
@self.Constraint(
time, doc="Shell side outlet enthalpy is saturated water enthalpy")
def saturation_eqn(b, t):
return (hot_side.properties_out[t].enth_mol ==
hot_side.properties_in[t].enth_mol_sat_phase["Liq"])
def build(self):
"""
Building model
Args:
None
Returns:
None
"""
########################################################################
# Call UnitModel.build to setup dynamics and configure #
########################################################################
super().build()
self._process_config()
config = self.config
########################################################################
# Add variables #
########################################################################
# Use side 1 units as basis
s1_metadata = config.hot_side_config.property_package.get_metadata()
q_units = s1_metadata.get_derived_units("power")
u_units = s1_metadata.get_derived_units("heat_transfer_coefficient")
a_units = s1_metadata.get_derived_units("area")
t_units = s1_metadata.get_derived_units("temperature")
u = self.overall_heat_transfer_coefficient = Var(
self.flowsheet().config.time,
domain=PositiveReals,
initialize=100.0,
doc="Overall heat transfer coefficient",
units=u_units)
a = self.area = Var(domain=PositiveReals,
initialize=1000.0,
doc="Heat exchange area",
units=a_units)
self.delta_temperature_in = Var(
self.flowsheet().config.time,
initialize=10.0,
doc="Temperature difference at the hot inlet end",
units=t_units)
self.delta_temperature_out = Var(
self.flowsheet().config.time,
initialize=10.1,
doc="Temperature difference at the hot outlet end",
units=t_units)
if self.config.flow_pattern == HeatExchangerFlowPattern.crossflow:
self.crossflow_factor = Var(
self.flowsheet().config.time,
initialize=1.0,
doc="Factor to adjust coutercurrent flow heat "
"transfer calculation for cross flow.",
)
f = self.crossflow_factor
########################################################################
# Add control volumes #
########################################################################
_make_heater_control_volume(
self,
"side_1",
config.hot_side_config,
dynamic=config.dynamic,
has_holdup=config.has_holdup,
)
_make_heater_control_volume(
self,
"side_2",
config.cold_side_config,
dynamic=config.dynamic,
has_holdup=config.has_holdup,
)
# Add named references to side_1 and side_2, side 1 and 2 maintain
# backward compatability and are names the user doesn't need to worry
# about. The sign convention for duty is heat from side 1 to side 2 is
# positive
add_object_reference(self, config.hot_side_name, self.side_1)
add_object_reference(self, config.cold_side_name, self.side_2)
# Add convienient references to heat duty.
self.heat_duty = Reference(self.side_2.heat)
# Need to do this as Reference does not have units (Pyomo fixing this)
q = self.side_2.heat
########################################################################
# Add ports #
########################################################################
# Keep old port names, just for backward compatability
self.add_inlet_port(name="inlet_1",
block=self.side_1,
doc="Hot side inlet")
self.add_inlet_port(name="inlet_2",
block=self.side_2,
doc="Cold side inlet")
self.add_outlet_port(name="outlet_1",
block=self.side_1,
doc="Hot side outlet")
self.add_outlet_port(name="outlet_2",
block=self.side_2,
doc="Cold side outlet")
# Using Andrew's function for now, I think Pyomo's refrence has trouble
# with scalar (pyomo) components.
add_object_reference(self, config.hot_side_name + "_inlet",
self.inlet_1)
add_object_reference(self, config.cold_side_name + "_inlet",
self.inlet_2)
add_object_reference(self, config.hot_side_name + "_outlet",
self.outlet_1)
add_object_reference(self, config.cold_side_name + "_outlet",
self.outlet_2)
########################################################################
# Add end temperature differnece constraints #
########################################################################
@self.Constraint(self.flowsheet().config.time)
def delta_temperature_in_equation(b, t):
if b.config.flow_pattern == HeatExchangerFlowPattern.cocurrent:
return (b.delta_temperature_in[t] ==
b.side_1.properties_in[t].temperature -
pyunits.convert(b.side_2.properties_in[t].temperature,
to_units=t_units))
else:
return (b.delta_temperature_in[t] ==
b.side_1.properties_in[t].temperature -
pyunits.convert(b.side_2.properties_out[t].temperature,
to_units=t_units))
@self.Constraint(self.flowsheet().config.time)
def delta_temperature_out_equation(b, t):
if b.config.flow_pattern == HeatExchangerFlowPattern.cocurrent:
return (b.delta_temperature_out[t] ==
b.side_1.properties_out[t].temperature -
pyunits.convert(b.side_2.properties_out[t].temperature,
to_units=t_units))
else:
return (b.delta_temperature_out[t] ==
b.side_1.properties_out[t].temperature -
pyunits.convert(b.side_2.properties_in[t].temperature,
to_units=t_units))
########################################################################
# Add a unit level energy balance #
########################################################################
@self.Constraint(self.flowsheet().config.time)
def unit_heat_balance(b, t):
return 0 == (
self.side_1.heat[t] +
pyunits.convert(self.side_2.heat[t], to_units=q_units))
########################################################################
# Add delta T calculations using callack function, lots of options, #
# and users can provide their own if needed #
########################################################################
config.delta_temperature_callback(self)
########################################################################
# Add Heat transfer equation #
########################################################################
deltaT = self.delta_temperature
@self.Constraint(self.flowsheet().config.time)
def heat_transfer_equation(b, t):
if self.config.flow_pattern == HeatExchangerFlowPattern.crossflow:
return pyunits.convert(
q[t], to_units=q_units) == (f[t] * u[t] * a * deltaT[t])
else:
return pyunits.convert(q[t], to_units=q_units) == (u[t] * a *
deltaT[t])
########################################################################
# Add symbols for LaTeX equation rendering #
########################################################################
self.overall_heat_transfer_coefficient.latex_symbol = "U"
self.area.latex_symbol = "A"
self.side_1.heat.latex_symbol = "Q_1"
self.side_2.heat.latex_symbol = "Q_2"
self.delta_temperature.latex_symbol = "\\Delta T"
