Merge branch 'dev'

Author: fwitte

.gitignore

@@ -1,5 +1,6 @@
 *.py[cod]
 __pycache__
+__pint_cache__
 
 # C extensions
 *.so

docs/modules/components.rst

@@ -34,9 +34,13 @@ well as the equations.
   * :py:class:`Solar collector <tespy.components.heat_exchangers.solar_collector.SolarCollector>`
   * :py:class:`Parabolic trough <tespy.components.heat_exchangers.parabolic_trough.ParabolicTrough>`
   * :py:class:`Heat exchanger <tespy.components.heat_exchangers.base.HeatExchanger>`
+  * :py:class:`Parallel flow heat exchanger <tespy.components.heat_exchangers.parallel.ParallelFlowHeatExchanger>`:
+    Analogue component to the :code:`HeatExchanger` but with flows in parallel.
+    All other types of heat exchangers (below) as well as the
+    :code:`HeatExchanger` base class assume counter current flow!
   * :py:class:`Condenser <tespy.components.heat_exchangers.condenser.Condenser>`
   * :py:class:`Desuperheater <tespy.components.heat_exchangers.desuperheater.Desuperheater>`
-  * :py:class:`Moving Boundary Heat exchanger <tespy.components.heat_exchangers.movingboundary.MovingBoundaryHeatExchanger>`:
+  * :py:class:`Moving boundary heat exchanger <tespy.components.heat_exchangers.movingboundary.MovingBoundaryHeatExchanger>`:
     Advanced heat exchanger class, automatically identifying phase change
     sections in the heat transfer of both sides and assigning individual UA
     values per section of heat transfer

docs/whats_new.rst

@@ -3,6 +3,7 @@ What's New
 
 Discover notable new features and improvements in each release
 
+.. include::  whats_new/v0-9-6.rst
 .. include::  whats_new/v0-9-5.rst
 .. include::  whats_new/v0-9-4.rst
 .. include::  whats_new/v0-9-3.rst

docs/whats_new/v0-9-5.rst

@@ -15,15 +15,19 @@ New Features
   - For pure fluids, this will be the same temperature, for mixtures (e.g. as
     accessible through REFPROP it will not)!
   - For :code:`td_bubble`:
+
     - A **positive** value indicates a temperature **below** bubble temperature
       by the specified value.
     - A **negative** value indicates a temperature **above** bubble temperature
       by the specified value.
+
   - For :code:`td_dew`:
+
     - A **positive** value indicates a temperature **above** dew temperature
       by the specified value.
     - A **negative** value indicates a temperature **below** dew temperature
       by the specified value.
+
   - You can also specify :code:`td_bubble=0` or :code:`td_dew=0`, which will
     enforce saturated liquid or saturated gas state.
 

docs/whats_new/v0-9-6.rst

@@ -0,0 +1,25 @@
+v0.9.6 - Kelvin's Kingdom (September, 22, 2025)
++++++++++++++++++++++++++++++++++++++++++++++++
+
+New Features
+############
+- There is a new component :code:`ParallelFlowHeatExchanger` implementing
+  parallel flow heat exchange, which works analogously to the
+  counter current variant :code:`HeatExchanger`
+  (`PR #766 <https://github.com/oemof/tespy/pull/766>`__).
+
+Bug Fixes
+#########
+- Calculation with humid air (water air mixtures) were broken for a state
+  where partial pressure of the water exactly corresponds the saturation
+  pressure at the given temperature of the mixture. Now there is an additional
+  check in place to make sure the correct calculations are employed
+  (`PR #774 <https://github.com/oemof/tespy/pull/774>`__).
+- The caching for pint broke when the python version of an environment was
+  changed. Now a :code:`__pint_cache__` is placed in the tespy installation
+  folder, to which the :code:`cache_folder` of pint's :code:`UnitRegistry` is
+  linked (`PR #777 <https://github.com/oemof/tespy/pull/777>`__).
+
+Contributors
+############
+- Francesco Witte (`@fwitte <https://github.com/fwitte>`__)

pyproject.toml

@@ -24,7 +24,7 @@ exclude = ["docs/_build"]
 
 [project]
 name = "tespy"
-version = "0.9.5.post1"
+version = "0.9.6"
 description = "Thermal Engineering Systems in Python (TESPy)"
 readme = "README.rst"
 authors = [

src/tespy/__init__.py

@@ -3,7 +3,7 @@
 import os
 
 __datapath__ = os.path.join(importlib.resources.files("tespy"), "data")
-__version__ = '0.9.5.post1 - Kelvin\'s Kingdom'
+__version__ = '0.9.6 - Kelvin\'s Kingdom'
 
 # tespy data and connections import
 from . import connections  # noqa: F401

src/tespy/components/__init__.py

@@ -12,6 +12,7 @@
 from .heat_exchangers.desuperheater import Desuperheater  # noqa: F401
 from .heat_exchangers.movingboundary import MovingBoundaryHeatExchanger  # noqa: F401
 from .heat_exchangers.parabolic_trough import ParabolicTrough  # noqa: F401
+from .heat_exchangers.parallel import ParallelFlowHeatExchanger  # noqa: F401
 from .heat_exchangers.simple import SimpleHeatExchanger  # noqa: F401
 from .heat_exchangers.solar_collector import SolarCollector  # noqa: F401
 from .nodes.droplet_separator import DropletSeparator  # noqa: F401

src/tespy/components/component.py

@@ -1000,12 +1000,13 @@ def pr_structure_matrix(self, k, pr=None, inconn=0, outconn=0):
 
     def variable_equality_structure_matrix(self, k, **kwargs):
         r"""
-        Create pairwise linear relationship between two variables for all
-        inlets and the respective outlets
+        Create pairwise linear relationship between two variables :code:`var`
+        for all inlets and the respective outlets. This usually is applied to
+        mass flow, pressure, enthalpy and fluid composition.
 
         .. math::
 
-            h_\ŧext{in,i} = h_\text{out,i}
+            var_\text{in,i} = var_\text{out,i}
 
         Parameters
         ----------

src/tespy/components/heat_exchangers/base.py

@@ -445,12 +445,8 @@ def calculate_td_log(self):
 
         if T_i1 <= T_o2:
             T_i1 = T_o2 + 0.01
-        if T_i1 <= T_o2:
-            T_o2 = T_i1 - 0.01
-        if T_i1 <= T_o2:
-            T_o1 = T_i2 + 0.02
         if T_o1 <= T_i2:
-            T_i2 = T_o1 - 0.02
+            T_o1 = T_i2 + 0.01
 
         ttd_u = T_i1 - T_o2
         ttd_l = T_o1 - T_i2