Fix API for fluid back end selection and adjust corresponding tests

src/tespy/components/heat_exchangers/base.py

@@ -148,8 +148,7 @@ class HeatExchanger(Component):
     >>> from tespy.networks import Network
     >>> from tespy.tools import document_model
     >>> import shutil
-    >>> nw = Network(fluids=['water', 'air'], T_unit='C', p_unit='bar',
-    ... h_unit='kJ / kg', iterinfo=False)
+    >>> nw = Network(T_unit='C', p_unit='bar', h_unit='kJ / kg', iterinfo=False)
     >>> exhaust_hot = Source('Exhaust air outlet')
     >>> exhaust_cold = Sink('Exhaust air inlet')
     >>> cw_cold = Source('cooling water inlet')
@@ -169,9 +168,9 @@ class HeatExchanger(Component):
 
     >>> he.set_attr(pr1=0.98, pr2=0.98, ttd_u=5,
     ... design=['pr1', 'pr2', 'ttd_u'], offdesign=['zeta1', 'zeta2', 'kA_char'])
-    >>> cw_he.set_attr(fluid={'air': 0, 'water': 1}, T=10, p=3,
+    >>> cw_he.set_attr(fluid={'water': 1}, T=10, p=3,
     ... offdesign=['m'])
-    >>> ex_he.set_attr(fluid={'air': 1, 'water': 0}, v=0.1, T=35)
+    >>> ex_he.set_attr(fluid={'air': 1}, v=0.1, T=35)
     >>> he_ex.set_attr(T=17.5, p=1, design=['T'])
     >>> nw.solve('design')
     >>> nw.save('tmp')
@@ -700,7 +699,8 @@ def bus_func(self, bus):
                 h_{out,1} - h_{in,1} \right)
         """
         return self.inl[0].m.val_SI * (
-            self.outl[0].h.val_SI - self.inl[0].h.val_SI)
+            self.outl[0].h.val_SI - self.inl[0].h.val_SI
+        )
 
     def bus_func_doc(self, bus):
         r"""

src/tespy/components/heat_exchangers/parabolic_trough.py

@@ -182,7 +182,7 @@ class ParabolicTrough(SimpleHeatExchanger):
     >>> pt.set_attr(pr=1, aoi=aoi, doc=1,
     ... Tamb=20, A=1, eta_opt=0.816, c_1=0.0622, c_2=0.00023, E=E,
     ... iam_1=-1.59e-3, iam_2=9.77e-5)
-    >>> inc.set_attr(fluid={'S800': 1}, T=220, p=2)
+    >>> inc.set_attr(fluid={'S800': 1}, fluid_back_ends={'S800': 'INCOMP'}, T=220, p=2)
     >>> outg.set_attr(T=260)
     >>> nw.solve('design')
     >>> round(pt.Q.val, 0)

src/tespy/components/heat_exchangers/simple.py

@@ -492,7 +492,7 @@ def hazen_williams_func(self):
 
         return (
             (i.p.val_SI - o.p.val_SI) * np.sign(i.m.val_SI) -
-                (10.67 * abs(i[0]) ** 1.852 * self.L.val /
+                (10.67 * abs(i.m.val_SI) ** 1.852 * self.L.val /
                  (self.ks.val ** 1.852 * self.D.val ** 4.871)) *
                 (9.81 * ((v_i + v_o) / 2) ** 0.852))
 

src/tespy/connections/connection.py

@@ -398,17 +398,17 @@ def set_attr(self, **kwargs):
                 msg = 'Label can only be specified on instance creation.'
                 logger.error(msg)
                 raise TESPyConnectionError(msg)
+            elif 'fluid' in key:
+                self._fluid_specification(key, kwargs[key])
             elif key in self.property_data or key in self.property_data0:
                 # fluid specification
                 try:
                     float(kwargs[key])
                     is_numeric = True
                 except (TypeError, ValueError):
                     is_numeric = False
-                if 'fluid' in key:
-                    self._fluid_specification(key, kwargs[key])
 
-                elif key == 'state':
+                if key == 'state':
                     if kwargs[key] in ['l', 'g']:
                         self.state.set_attr(val=kwargs[key], is_set=True)
                     elif kwargs[key] is None:
@@ -528,7 +528,7 @@ def _fluid_specification(self, key, value):
         if key == "fluid":
             for fluid, fraction in value.items():
                 if fraction is not None:
-                    self.fluid.val["fluid"] = fraction
+                    self.fluid.val[fluid] = fraction
                     self.fluid.is_set.add(fluid)
                     if fluid in self.fluid.is_var:
                         self.fluid.is_var.remove(fluid)
@@ -554,7 +554,7 @@ def _fluid_specification(self, key, value):
             logger.error(msg)
             raise KeyError(msg)
 
-    def _check_fluid_datatypes(key, value):
+    def _check_fluid_datatypes(self, key, value):
         if key == "fluid_balance":
             if not isinstance(value, bool):
                 msg = "Datatype for 'fluid_balance' must be boolean."
@@ -590,6 +590,8 @@ def get_attr(self, key):
 
     def _create_fluid_wrapper(self):
         for fluid in self.fluid.val:
+            if fluid in self.fluid.wrapper:
+                continue
             if fluid in self.fluid.engine and fluid in self.fluid.back_end:
                 pass
             elif fluid in self.fluid.engine:
@@ -814,10 +816,16 @@ def calc_results(self):
             self.s.val_SI = self.calc_s()
 
         if number_fluids == 1:
-            if not self.x.is_set:
-                self.x.val_SI = self.calc_x()
-            if not self.Td_bp.is_set:
-                self.Td_bp.val_SI = self.calc_Td_bp()
+            try:
+                if not self.x.is_set:
+                    self.x.val_SI = self.calc_x()
+            except ValueError:
+                self.x.val_SI = np.nan
+            try:
+                if not self.Td_bp.is_set:
+                    self.Td_bp.val_SI = self.calc_Td_bp()
+            except ValueError:
+                self.x.val_SI = np.nan
 
         for prop in fpd.keys():
             self.get_attr(prop).val = convert_from_SI(

src/tespy/networks/network.py

@@ -763,6 +763,7 @@ def init_components(self):
                 self.results[comp_type] = pd.DataFrame(
                     columns=cols, dtype='float64')
             if comp_type not in self.specifications:
+
                 cols, groups, chars = [], [], []
                 for col, data in comp.parameters.items():
                     if isinstance(data, dc_cp):
@@ -907,7 +908,13 @@ def propagate_fluid_wrappers(self):
                     if f not in c.fluid.wrapper and f in fluid_set_wrappers:
                         c.fluid.wrapper[f] = fluid_set_wrappers[f]
                     elif f not in c.fluid.wrapper:
-                        c._create_fluid_wrapper(f, fp.CoolPropWrapper, "HEOS")
+                        msg = (
+                            f"The fluid {f} seems to be a potential fluid for "
+                            "connection, however, there has is no fluid "
+                            "wrapper available for this fluid on the same "
+                            "branch. Creating a default wrapper."
+                        )
+                        c._create_fluid_wrapper()
 
     def presolve_massflow_topology(self):
 
@@ -1056,6 +1063,21 @@ def presolve_fluid_topology(self):
                 }
                 self.num_conn_vars += 1
 
+    def _reset_topology_reduction_specifications(self):
+        for c in self.conns["object"]:
+            if hasattr(c, "_m_tmp"):
+                value = c.m.val_SI
+                unit = c.m.unit
+                c.m = c._m_tmp
+                c.m.val_SI = value
+                c.m.unit = unit
+                del c._m_tmp
+            if hasattr(c, "_fluid_tmp"):
+                val = c.fluid.val
+                c.fluid = c._fluid_tmp
+                c.fluid.val = val
+                del c._fluid_tmp
+
     def init_set_properties(self):
         """Specification of SI values for user set values."""
         self.all_fluids = []
@@ -1887,6 +1909,7 @@ def solve(self, mode, init_path=None, design_path=None,
         self.initialise()
 
         if init_only:
+            self._reset_topology_reduction_specifications()
             return
 
         msg = 'Starting solver.'
@@ -2396,20 +2419,9 @@ def postprocessing(self):
 
     def process_connections(self):
         """Process the Connection results."""
-        for c in self.conns['object']:
-            if hasattr(c, "_m_tmp"):
-                value = c.m.val_SI
-                unit = c.m.unit
-                c.m = c._m_tmp
-                c.m.val_SI = value
-                c.m.unit = unit
-                del c._m_tmp
-            if hasattr(c, "_fluid_tmp"):
-                val = c.fluid.val
-                c.fluid = c._fluid_tmp
-                c.fluid.val = val
-                del c._fluid_tmp
+        self._reset_topology_reduction_specifications()
 
+        for c in self.conns['object']:
             c.good_starting_values = True
             c.calc_results()
 

src/tespy/tools/fluid_properties/wrappers.py

@@ -77,7 +77,10 @@ def __init__(self, fluid, back_end=None) -> None:
     def _set_constants(self):
         self._T_min = self.AS.trivial_keyed_output(CP.iT_min)
         self._T_max = self.AS.trivial_keyed_output(CP.iT_max)
-        self._aliases = CP.CoolProp.get_aliases(self.fluid)
+        try:
+            self._aliases = CP.CoolProp.get_aliases(self.fluid)
+        except RuntimeError:
+            self._aliases = [self.fluid]
 
         if self.back_end == "INCOMP":
             self._p_min = 1e2

tests/test_components/test_heat_exchangers.py

@@ -57,7 +57,7 @@ def test_SimpleHeatExchanger(self):
         """Test component properties of simple heat exchanger."""
         instance = SimpleHeatExchanger('heat exchanger')
         self.setup_SimpleHeatExchanger_network(instance)
-        fl = {'Ar': 0, 'H2O': 1, 'S800': 0}
+        fl = {'H2O': 1}
         self.c1.set_attr(fluid=fl, m=1, p=10, T=100)
         # trigger heat exchanger parameter groups
         instance.set_attr(hydro_group='HW', L=100, ks=100, pr=0.99, Tamb=20)
@@ -156,8 +156,9 @@ def test_ParabolicTrough(self):
         """Test component properties of parabolic trough."""
         instance = ParabolicTrough('parabolic trough')
         self.setup_SimpleHeatExchanger_network(instance)
-        fl = {'Ar': 0, 'H2O': 0, 'S800': 1}
-        self.c1.set_attr(fluid=fl, p=2, T=200)
+        fl = {'S800': 1}
+        fbe = {"S800": "INCOMP"}
+        self.c1.set_attr(fluid=fl, fluid_back_ends=fbe, p=2, T=200)
         self.c2.set_attr(T=350)
 
         # test grouped parameter settings with missing parameters
@@ -261,7 +262,7 @@ def test_SolarCollector(self):
         """Test component properties of solar collector."""
         instance = SolarCollector('solar collector')
         self.setup_SimpleHeatExchanger_network(instance)
-        fl = {'Ar': 0, 'H2O': 1, 'S800': 0}
+        fl = {'H2O': 1}
         self.c1.set_attr(fluid=fl, p=10, T=30)
         self.c2.set_attr(T=70)
 
@@ -341,9 +342,9 @@ def test_HeatExchanger(self):
         instance.set_attr(pr1=0.98, pr2=0.98, ttd_u=5,
                           design=['pr1', 'pr2', 'ttd_u'],
                           offdesign=['zeta1', 'zeta2', 'kA_char'])
-        self.c1.set_attr(T=120, p=3, fluid={'Ar': 0, 'H2O': 1, 'S800': 0})
+        self.c1.set_attr(T=120, p=3, fluid={'H2O': 1})
         self.c2.set_attr(T=70)
-        self.c3.set_attr(T=40, p=5, fluid={'Ar': 1, 'H2O': 0, 'S800': 0})
+        self.c3.set_attr(T=40, p=5, fluid={'Ar': 1})
         b = Bus('heat transfer', P=-80e3)
         b.add_comps({'comp': instance})
         self.nw.add_busses(b)
@@ -447,10 +448,11 @@ def test_Condenser(self):
         self.setup_HeatExchanger_network(instance)
 
         # design specification
-        instance.set_attr(pr1=0.98, pr2=0.98, ttd_u=5,
-                          offdesign=['zeta2', 'kA_char'])
-        self.c1.set_attr(T=100, p0=0.5, fluid={'Ar': 0, 'H2O': 1, 'S800': 0})
-        self.c3.set_attr(T=30, p=5, fluid={'Ar': 0, 'H2O': 1, 'S800': 0})
+        instance.set_attr(
+            pr1=0.98, pr2=0.98, ttd_u=5, offdesign=['zeta2', 'kA_char']
+        )
+        self.c1.set_attr(T=100, p0=0.5, fluid={'H2O': 1})
+        self.c3.set_attr(T=30, p=5, fluid={'H2O': 1})
         self.c4.set_attr(T=40)
         instance.set_attr(Q=-80e3)
         self.nw.solve('design')
@@ -483,7 +485,7 @@ def test_Condenser(self):
 
         # test upper terminal temperature difference. For the component
         # condenser the temperature of the condensing fluid is relevant.
-        ttd_u = round(T_sat_p(self.c1.get_flow()) - self.c4.T.val_SI, 1)
+        ttd_u = round(self.c1.calc_T_sat() - self.c4.T.val_SI, 1)
         p = round(self.c1.p.val_SI, 5)
         msg = ('Value of terminal temperature difference must be ' +
                str(round(instance.ttd_u.val, 1)) + ', is ' +
@@ -517,10 +519,8 @@ def test_CondenserWithEvaporation(self):
 
         # design specification
         instance.set_attr(pr1=1, pr2=1, offdesign=["kA"])
-        self.c1.set_attr(x=1, p=1, fluid={'Ar': 0, 'H2O': 1, 'S800': 0}, m=1)
-        self.c3.set_attr(
-            x=0, p=0.7, fluid={'Ar': 0, 'H2O': 1, 'S800': 0}, m=2, design=["m"]
-        )
+        self.c1.set_attr(x=1, p=1, fluid={'H2O': 1}, m=1)
+        self.c3.set_attr(x=0, p=0.7, fluid={'H2O': 1}, m=2, design=["m"])
         self.nw.solve('design')
         self.nw._convergence_check()
         ttd_l = round(instance.ttd_l.val, 3)

tests/test_components/test_turbomachinery.py

@@ -44,7 +44,7 @@ def test_Compressor(self):
         self.setup_network(instance)
 
         # compress NH3, other fluids in network are for turbine, pump, ...
-        fl = {'N2': 1, 'O2': 0, 'Ar': 0, 'DowQ': 0, 'NH3': 0}
+        fl = {'N2': 1}
         self.c1.set_attr(fluid=fl, v=1, p=1, T=5)
         self.c2.set_attr(p=6)
         instance.set_attr(eta_s=0.8)
@@ -54,7 +54,7 @@ def test_Compressor(self):
 
         # test isentropic efficiency value
         eta_s_d = (
-            (isentropic(self.c1.get_flow(), self.c2.get_flow()) -
+            (isentropic(self.c1.p.val_SI, self.c1.h.val_SI, self.c2.p.val_SI, self.c1.fluid_data, self.c1.mixing_rule) -
              self.c1.h.val_SI) / (self.c2.h.val_SI - self.c1.h.val_SI))
         msg = ('Value of isentropic efficiency must be ' + str(eta_s_d) +
                ', is ' + str(instance.eta_s.val) + '.')
@@ -67,7 +67,7 @@ def test_Compressor(self):
 
         # test calculated value
         eta_s = (
-            (isentropic(self.c1.get_flow(), self.c2.get_flow()) -
+            (isentropic(self.c1.p.val_SI, self.c1.h.val_SI, self.c2.p.val_SI, self.c1.fluid_data, self.c1.mixing_rule) -
              self.c1.h.val_SI) / (self.c2.h.val_SI - self.c1.h.val_SI))
         msg = ('Value of isentropic efficiency must be ' + str(eta_s) +
                ', is ' + str(instance.eta_s.val) + '.')
@@ -160,25 +160,26 @@ def test_Pump(self):
         """Test component properties of pumps."""
         instance = Pump('pump')
         self.setup_network(instance)
-        fl = {'N2': 0, 'O2': 0, 'Ar': 0, 'DowQ': 1, 'NH3': 0}
-        self.c1.set_attr(fluid=fl, v=1, p=5, T=50)
+        fl = {'DowQ': 1}
+        fbe = {'DowQ': 'INCOMP'}
+        self.c1.set_attr(fluid=fl, fluid_back_ends=fbe, v=1, p=5, T=50)
         self.c2.set_attr(p=7)
         instance.set_attr(eta_s=1)
         self.nw.solve('design')
         self.nw._convergence_check()
 
         # test calculated value for efficiency
         eta_s = (
-            (isentropic(self.c1.get_flow(), self.c2.get_flow()) -
+            (isentropic(self.c1.p.val_SI, self.c1.h.val_SI, self.c2.p.val_SI, self.c1.fluid_data, self.c1.mixing_rule) -
              self.c1.h.val_SI) / (self.c2.h.val_SI - self.c1.h.val_SI))
         msg = ('Value of isentropic efficiency must be ' + str(eta_s) +
                ', is ' + str(instance.eta_s.val) + '.')
         assert eta_s == instance.eta_s.val, msg
 
         # isentropic efficiency of 1 means inlet and outlet entropy are
         # identical
-        s1 = round(s_mix_ph(self.c1.get_flow()), 4)
-        s2 = round(s_mix_ph(self.c2.get_flow()), 4)
+        s1 = round(self.c1.calc_s(), 4)
+        s2 = round(self.c2.calc_s(), 4)
         msg = ('Value of entropy must be identical for inlet (' + str(s1) +
                ') and outlet (' + str(s2) +
                ') at 100 % isentropic efficiency.')
@@ -251,8 +252,7 @@ def test_Turbine(self):
         """Test component properties of turbines."""
         instance = Turbine('turbine')
         self.setup_network(instance)
-        fl = {'N2': 0.7556, 'O2': 0.2315, 'Ar': 0.0129, 'DowQ': 0,
-              'NH3': 0}
+        fl = {'N2': 0.7556, 'O2': 0.2315, 'Ar': 0.0129}
         self.c1.set_attr(fluid=fl, m=15, p=10)
         self.c2.set_attr(p=1, T=25)
         instance.set_attr(eta_s=0.85)
@@ -263,7 +263,7 @@ def test_Turbine(self):
         # design value of isentropic efficiency
         eta_s_d = (
             (self.c2.h.val_SI - self.c1.h.val_SI) / (
-                isentropic(self.c1.get_flow(), self.c2.get_flow()) -
+                isentropic(self.c1.p.val_SI, self.c1.h.val_SI, self.c2.p.val_SI, self.c1.fluid_data, self.c1.mixing_rule) -
                 self.c1.h.val_SI))
         msg = ('Value of isentropic efficiency must be ' +
                str(round(eta_s_d, 3)) + ', is ' + str(instance.eta_s.val) +
@@ -276,7 +276,7 @@ def test_Turbine(self):
         self.nw._convergence_check()
         eta_s = (
             (self.c2.h.val_SI - self.c1.h.val_SI) / (
-                isentropic(self.c1.get_flow(), self.c2.get_flow()) -
+                isentropic(self.c1.p.val_SI, self.c1.h.val_SI, self.c2.p.val_SI, self.c1.fluid_data, self.c1.mixing_rule) -
                 self.c1.h.val_SI))
         msg = ('Value of isentropic efficiency must be ' + str(eta_s) +
                ', is ' + str(instance.eta_s.val) + '.')
@@ -342,7 +342,7 @@ def test_Turbomachine(self):
                instance.component() + '.')
         assert 'turbomachine' == instance.component(), msg
         self.setup_network(instance)
-        fl = {'N2': 0.7556, 'O2': 0.2315, 'Ar': 0.0129, 'DowQ': 0, 'NH3': 0}
+        fl = {'N2': 0.7556, 'O2': 0.2315, 'Ar': 0.0129}
         self.c1.set_attr(fluid=fl, m=10, p=1, h=1e5)
         self.c2.set_attr(p=3, h=2e5)
 

tests/test_errors.py

@@ -655,6 +655,7 @@ def test_missing_CharMap_files():
 def test_h_mix_pQ_on_mixtures():
     c = Connection(Source("test"), "out1", Sink("test2"), "in1")
     c.set_attr(fluid={"O2": 0.24, "N2": 0.76})
+    c._create_fluid_wrapper()
     c.build_fluid_data()
     with raises(ValueError):
         h_mix_pQ(1e5, 0.5, c.fluid_data, c.mixing_rule)