def build(self):
"""
Add model equations to the unit model. This is called by a default block
construnction rule when the unit model is created.
"""
super().build() # Basic unit model build/read config
config = self.config # shorter config pointer
# The thermodynamic expression writer object, te, writes expressions
# including external function calls to calculate thermodynamic quantities
# from a set of state variables.
_assert_properties(config.property_package)
te = ThermoExpr(blk=self, parameters=config.property_package)
eff = self.efficiency_isentropic = pyo.Var(self.flowsheet().time,
initialize=0.9,
doc="Isentropic efficiency")
eff.fix()
pratio = self.ratioP = pyo.Var(self.flowsheet().time,
initialize=0.7,
doc="Ratio of outlet to inlet pressure")
# Some shorter refernces to property blocks
properties_in = self.control_volume.properties_in
properties_out = self.control_volume.properties_out
@self.Expression(self.flowsheet().time,
doc="Outlet isentropic enthalpy")
def h_is(b, t):
return te.h(s=properties_in[t].entr_mol,
p=properties_out[t].pressure)
@self.Expression(self.flowsheet().time,
doc="Isentropic enthalpy change")
def delta_enth_isentropic(b, t):
return self.h_is[t] - properties_in[t].enth_mol
@self.Expression(self.flowsheet().time, doc="Isentropic work")
def work_isentropic(b, t):
return properties_in[t].flow_mol * (properties_in[t].enth_mol -
self.h_is[t])
@self.Expression(self.flowsheet().time, doc="Outlet enthalpy")
def h_o(b, t): # Early access to the outlet enthalpy and work
return properties_in[t].enth_mol - eff[t] * (
properties_in[t].enth_mol - self.h_is[t])
@self.Constraint(self.flowsheet().time)
def eq_work(b, t): # Work from energy balance
return properties_out[t].enth_mol == self.h_o[t]
@self.Constraint(self.flowsheet().time)
def eq_pressure_ratio(b, t):
return (pratio[t] *
properties_in[t].pressure == properties_out[t].pressure)
@self.Expression(self.flowsheet().time)
def work_mechanical(b, t):
return b.control_volume.work[t]
def build(self):
"""
Add model equations to the unit model. This is called by a default block
construnction rule when the unit model is created.
"""
super().build() # Basic unit model build/read config
config = self.config # shorter config pointer
# The thermodynamic expression writer object, te, writes expressions
# including external function calls to calculate thermodynamic quantities
# from a set of state variables.
_assert_properties(config.property_package)
te = ThermoExpr(blk=self, parameters=config.property_package)
self.valve_opening = pyo.Var(
self.flowsheet().config.time,
initialize=1,
doc="Fraction open for valve from 0 to 1",
)
self.Cv = pyo.Var(
initialize=0.1,
doc="Valve flow coefficent, for vapor "
"[mol/s/Pa] for liquid [mol/s/Pa]",
units=pyo.units.mol/pyo.units.s/pyo.units.Pa
)
#self.Cv.fix()
# set up the valve function rule. I'm not sure these matter too much
# for us, but the options are easy enough to provide.
vfcb = self.config.valve_function_callback
vfselect = self.config.valve_function
if vfselect is not ValveFunctionType.custom and vfcb is not None:
_log.warning(f"A valve function callback was provided but the valve "
"function type is not custom.")
if vfselect == ValveFunctionType.linear:
_linear_callback(self)
elif vfselect == ValveFunctionType.quick_opening:
_quick_open_callback(self)
elif vfselect == ValveFunctionType.equal_percentage:
_equal_percentage_callback(self)
else:
if vfcb is None:
raise ConfigurationError(
"No custom valve function callback provided")
vfcb(self)
if self.config.phase == "Liq":
rule = _liquid_pressure_flow_rule
else:
rule = _vapor_pressure_flow_rule
self.pressure_flow_equation = pyo.Constraint(
self.flowsheet().config.time, rule=rule
)
def build(self):
"""
Add model equations to the unit model. This is called by a default block
construnction rule when the unit model is created.
"""
super().build() # Basic unit model build/read config
config = self.config # shorter config pointer
# The thermodynamic expression writer object, te, writes expressions
# including external function calls to calculate thermodynamic quantities
# from a set of state variables.
_assert_properties(config.property_package)
te = ThermoExpr(blk=self, parameters=config.property_package)
eff = self.efficiency_pump = pyo.Var(self.flowsheet().config.time,
initialize=0.9,
doc="Pump efficiency")
self.efficiency_isentropic = pyo.Reference(self.efficiency_pump[:])
pratio = self.ratioP = pyo.Var(self.flowsheet().config.time,
initialize=0.7,
doc="Ratio of outlet to inlet pressure")
# Some shorter refernces to property blocks
properties_in = self.control_volume.properties_in
properties_out = self.control_volume.properties_out
@self.Expression(self.flowsheet().config.time,
doc="Thermodynamic work")
def work_fluid(b, t):
return properties_out[t].flow_vol * (self.deltaP[t])
@self.Expression(self.flowsheet().config.time,
doc="Work required to drive the pump.")
def shaft_work(b, t): # Early access to the outlet enthalpy and work
return self.work_fluid[t] / eff[t]
@self.Constraint(self.flowsheet().config.time)
def eq_work(b, t): # outlet enthalpy coens from energy balance
return self.control_volume.work[t] == self.shaft_work[t]
@self.Constraint(self.flowsheet().config.time)
def eq_pressure_ratio(b, t):
return (pratio[t] *
properties_in[t].pressure == properties_out[t].pressure)