Merge pull request #478 from oemof/fix/temperature-upper-limit-mixtures

Increase upper limit for mixture temperature root finding

src/tespy/connections/connection.py

@@ -36,6 +36,7 @@
 from tespy.tools.fluid_properties import viscosity_mix_ph
 from tespy.tools.fluid_properties.functions import dT_mix_ph_dfluid
 from tespy.tools.fluid_properties.functions import p_sat_T
+from tespy.tools.fluid_properties.helpers import get_mixture_temperature_range
 from tespy.tools.fluid_properties.helpers import get_number_of_fluids
 from tespy.tools.global_vars import ERR
 from tespy.tools.global_vars import fluid_property_data as fpd
@@ -917,7 +918,15 @@ def calc_results(self):
                 )
                 logger.error(msg)
                 _converged = False
-
+            else:
+                _, Tmax = get_mixture_temperature_range(self.fluid_data)
+                if self.T.val_SI > Tmax:
+                    msg = (
+                        "The temperature value of the mixture is above the "
+                        "upper temperature limit of a mixture component. "
+                        "The resulting temperature might not be erroneous."
+                    )
+                    logger.warning(msg)
         else:
             try:
                 if not self.x.is_set:

src/tespy/tools/fluid_properties/helpers.py

@@ -70,6 +70,8 @@ def inverse_temperature_mixture(p=None, target_value=None, fluid_data=None, T0=N
     if T0 is None:
         T0 = (valmin + valmax) / 2.0
 
+    valmax *= 2
+
     function_kwargs = {
         "p": p, "fluid_data": fluid_data, "T": T0,
         "function": f, "parameter": "T" , "delta": 0.01

tests/test_components/test_combustion.py

@@ -9,9 +9,10 @@
 
 SPDX-License-Identifier: MIT
 """
-
 import shutil
 
+import pytest
+
 from tespy.components import CombustionChamber
 from tespy.components import CombustionEngine
 from tespy.components import DiabaticCombustionChamber
@@ -103,6 +104,20 @@ def test_CombustionChamber(self):
                str(round(self.c3.fluid.val['O2'], 4)) + '.')
         assert 0.0 == round(self.c3.fluid.val['O2'], 4), msg
 
+    def test_CombustionChamberHighTemperature(self):
+        instance = CombustionChamber('combustion chamber')
+        self.setup_CombustionChamber_network(instance)
+
+        # connection parameter specification
+        air = {'N2': 0.8, 'O2': 0.2}
+        fuel = {'CH4': 1}
+        self.c1.set_attr(fluid=air, p=1, T=30, m=1)
+        self.c2.set_attr(fluid=fuel, T=30)
+        instance.set_attr(lamb=1)
+        self.nw.solve('design')
+        self.nw._convergence_check()
+        assert self.c3.T.val_SI == pytest.approx(2110, abs=0.1)
+
     def test_DiabaticCombustionChamber(self):
         """
         Test component properties of diabatic combustion chamber.

tests/test_networks/test_binary_incompressible.py

@@ -51,4 +51,4 @@ def setup_method(self):
         self.nw.solve("design")
 
     def test_binaries(self):
-        self.nw._convergence_check()
+        self.nw._convergence_check()