Fix initialization of FpcTP with one phase (#1677)

* Fix initialization of FpcTP with one phase

* codecov

* typo

Author: dallan-keylogic

idaes/models/properties/modular_properties/base/generic_property.py

@@ -1691,15 +1691,14 @@ def fix_initialization_states(self):
 
         for k in self.values():
             # Also need to deactivate sum of mole fraction constraint
-            try:
+            if k.is_property_constructed("sum_mole_frac_out"):
                 k.sum_mole_frac_out.deactivate()
-            except AttributeError:
-                pass
+
             # Don't need equilibrium constraint for phase component flows
             if (
                 "flow_mol_phase_comp" in k.define_state_vars()
                 or "mole_frac_phase_comp" in k.define_state_vars()
-            ):
+            ) and k.is_property_constructed("equilibrium_constraint"):
                 k.equilibrium_constraint.deactivate()
 
             if k.is_property_constructed("inherent_equilibrium_constraint") and (
@@ -1793,9 +1792,7 @@ def initialize(
             # When state vars are fixed, check that DoF is 0
             for k in blk.values():
                 if degrees_of_freedom(k) != 0:
-                    # PYLINT-TODO
-                    # pylint: disable-next=broad-exception-raised
-                    raise Exception(
+                    raise InitializationError(
                         "State vars fixed but degrees of "
                         "freedom for state block is not zero "
                         "during initialization."

idaes/models/properties/modular_properties/state_definitions/tests/test_FpcTP.py

@@ -19,8 +19,16 @@
 import pytest
 import re
 from sys import modules
-
-from pyomo.environ import ConcreteModel, Constraint, Expression, Var, units as pyunits
+from copy import deepcopy
+
+from pyomo.environ import (
+    ConcreteModel,
+    Constraint,
+    Expression,
+    value,
+    Var,
+    units as pyunits,
+)
 from pyomo.util.check_units import check_units_equivalent, assert_units_consistent
 
 # Need define_default_scaling_factors, even though it is not used directly
@@ -53,8 +61,9 @@
 from idaes.models.properties.modular_properties.phase_equil.bubble_dew import (
     IdealBubbleDew,
 )
-from idaes.core.util.exceptions import ConfigurationError
+from idaes.core.util.exceptions import ConfigurationError, InitializationError
 import idaes.logger as idaeslog
+import idaes.core.util.model_statistics as mstat
 from idaes.core.util.model_statistics import degrees_of_freedom, large_residuals_set
 
 
@@ -1462,6 +1471,46 @@ def test_phase_equilibrium_legacy_initialization():
         ]
 
 
+@pytest.mark.component
+def test_legacy_initialization_dof_error():
+    # This test ensures that the correct exception is
+    # raised when there is a degree of freedom error
+    # during initialization
+    model = ConcreteModel()
+    model.fs = FlowsheetBlock(dynamic=False)
+
+    # Remove the liquid phase and phase equilibrium
+    # from the config dict
+    config = deepcopy(thermo_config_no_rxn)
+    config["phases"].pop("Liq")
+    config.pop("phases_in_equilibrium")
+    config.pop("phase_equilibrium_state")
+    config["components"]["H2O"].pop("phase_equilibrium_form")
+    config["components"]["CO2"].pop("phase_equilibrium_form")
+
+    model.fs.thermo_params = GenericParameterBlock(**config)
+
+    model.fs.state = model.fs.thermo_params.build_state_block(
+        model.fs.time, defined_state=False
+    )
+
+    model.fs.state[0].pressure.fix(101325.0)
+    model.fs.state[0].temperature.fix(398.0)
+
+    model.fs.state[0].flow_mol_phase_comp["Vap", "CO2"].fix(0.005)
+    model.fs.state[0].flow_mol_phase_comp["Vap", "H2O"].set_value(0.0005)
+
+    with pytest.raises(
+        InitializationError,
+        match=re.escape(
+            "State vars fixed but degrees of "
+            "freedom for state block is not zero "
+            "during initialization."
+        ),
+    ):
+        model.fs.state.initialize(state_vars_fixed=True)
+
+
 @pytest.mark.component
 def test_phase_equilibrium_initializer_object():
     # Create a pyomo model object
@@ -1504,3 +1553,71 @@ def test_phase_equilibrium_initializer_object():
             "fs.state[0.0].equilibrium_constraint[Vap,Liq,H2O]",
             "fs.state[0.0].equilibrium_constraint[Vap,Liq,CO2]",
         ]
+
+
+@pytest.mark.component
+def test_initializer_object_single_phase():
+    # This test ensures that FpcTP state variables can be
+    # initialized even if only a single phase is present
+    model = ConcreteModel()
+    model.fs = FlowsheetBlock(dynamic=False)
+
+    # Remove the liquid phase and phase equilibrium
+    # from the config dict
+    config = deepcopy(thermo_config_no_rxn)
+    config["phases"].pop("Liq")
+    config.pop("phases_in_equilibrium")
+    config.pop("phase_equilibrium_state")
+    config["components"]["H2O"].pop("phase_equilibrium_form")
+    config["components"]["CO2"].pop("phase_equilibrium_form")
+
+    model.fs.thermo_params = GenericParameterBlock(**config)
+
+    model.fs.state = model.fs.thermo_params.build_state_block(
+        model.fs.time, defined_state=False
+    )
+
+    model.fs.state[0].pressure.set_value(101325.0)
+    model.fs.state[0].temperature.set_value(398.0)
+
+    model.fs.state[0].flow_mol_phase_comp["Vap", "CO2"].set_value(0.005)
+    model.fs.state[0].flow_mol_phase_comp["Vap", "H2O"].set_value(0.0005)
+
+    assert_units_consistent(model)
+    # We expect 4 state variables: T, P, and two pc flows,
+    # and  2 non-state variables in mole_frac_phase_comp
+    # Because T and P don't appear in any constraints,
+    # they are not counted in degrees_of_freedom
+    vars_not_in_constraints = mstat.variables_not_in_activated_constraints_set(
+        model.fs.state[0]
+    )
+    assert len(vars_not_in_constraints) == 2
+    assert model.fs.state[0].pressure in vars_not_in_constraints
+    assert model.fs.state[0].temperature in vars_not_in_constraints
+
+    assert degrees_of_freedom(model) == 2
+
+    initializer = model.fs.state.default_initializer()
+
+    initializer.initialize(model.fs.state)
+
+    # Check that degrees of freedom are still the same
+    vars_not_in_constraints = mstat.variables_not_in_activated_constraints_set(
+        model.fs.state[0]
+    )
+    assert len(vars_not_in_constraints) == 2
+    assert model.fs.state[0].pressure in vars_not_in_constraints
+    assert model.fs.state[0].temperature in vars_not_in_constraints
+
+    assert degrees_of_freedom(model) == 2
+
+    assert value(model.fs.state[0].pressure) == 101325.0
+    assert value(model.fs.state[0].temperature) == 398.0
+    assert value(model.fs.state[0].flow_mol_phase_comp["Vap", "CO2"]) == 0.005
+    assert value(model.fs.state[0].flow_mol_phase_comp["Vap", "H2O"]) == 0.0005
+    assert value(model.fs.state[0].mole_frac_phase_comp["Vap", "CO2"]) == pytest.approx(
+        5 / 5.5
+    )
+    assert value(model.fs.state[0].mole_frac_phase_comp["Vap", "H2O"]) == pytest.approx(
+        0.5 / 5.5
+    )