added example model that demonstrates that energy is not conserved ar…

…ound zero flow this is for issue ibpsa#282
Mathadon · Jun 30, 2015 · 363add6 · 363add6
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diff --git a/Annex60/Fluid/MixingVolumes/Examples/MixingVolumeNonLinSysZeroFlow.mo b/Annex60/Fluid/MixingVolumes/Examples/MixingVolumeNonLinSysZeroFlow.mo
@@ -0,0 +1,69 @@
+within Annex60.Fluid.MixingVolumes.Examples;
+model MixingVolumeNonLinSysZeroFlow
+  "Mixing volume with a non-linear system around zero flow"
+  extends Modelica.Icons.Example;
+  package Medium = Annex60.Media.Water;
+  Annex60.Fluid.MixingVolumes.MixingVolume vol(
+    nPorts=2,
+    redeclare package Medium = Medium,
+    m_flow_nominal=1,
+    V=1,
+    energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
+    massDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
+    allowFlowReversal=false,
+    prescribedHeatFlowRate=true) "Steady state mixing volume"
+    annotation (Placement(transformation(extent={{-10,0},{10,20}})));
+  Annex60.Fluid.Sources.MassFlowSource_T sou(
+    nPorts=1,
+    redeclare package Medium = Medium,
+    use_m_flow_in=true) "Source"
+    annotation (Placement(transformation(extent={{-60,-10},{-40,10}})));
+  Annex60.Fluid.Sources.Boundary_pT sin(nPorts=1, redeclare package Medium =
+        Medium) "Sink"
+    annotation (Placement(transformation(extent={{60,-10},{40,10}})));
+  Modelica.Blocks.Sources.Ramp ramp(
+    height=-1,
+    duration=1,
+    offset=1) "Mass flow rate ramp"
+    annotation (Placement(transformation(extent={{-100,-2},{-80,18}})));
+  Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow preHea
+    "Prescribed heat flow"
+    annotation (Placement(transformation(extent={{-40,40},{-20,60}})));
+  Modelica.Blocks.Sources.RealExpression reaExp(y=(290 - vol.heatPort.T)*10)
+    "Thermal resistance equation"
+    annotation (Placement(transformation(extent={{-100,36},{-58,64}})));
+equation
+
+    assert(abs(vol.heatPort.Q_flow)<Modelica.Constants.small or time<1, "Heat flow leakage around zero flow!");
+  connect(sou.ports[1], vol.ports[1])
+    annotation (Line(points={{-40,0},{-2,0}}, color={0,127,255}));
+  connect(vol.ports[2],sin. ports[1])
+    annotation (Line(points={{2,0},{2,0},{40,0}}, color={0,127,255}));
+  connect(ramp.y, sou.m_flow_in)
+    annotation (Line(points={{-79,8},{-60,8}}, color={0,0,127}));
+  connect(preHea.port, vol.heatPort)
+    annotation (Line(points={{-20,50},{-10,50},{-10,10}}, color={191,0,0}));
+  connect(reaExp.y, preHea.Q_flow) annotation (Line(points={{-55.9,50},{-55.9,50},
+          {-40,50}}, color={0,0,127}));
+  annotation (                                                         Diagram(
+        coordinateSystem(preserveAspectRatio=false, extent={{-100,-100},{100,100}})),
+    experiment(
+      StopTime=2,
+      __Dymola_fixedstepsize=20,
+      __Dymola_Algorithm="Dassl"),
+    __Dymola_experimentSetupOutput,
+    Documentation(revisions="<html>
+<ul>
+<li>
+June 30, 2015 by Filip Jorissen:<br/>
+First implementation.
+</li>
+</ul>
+</html>", info="<html>
+<p>
+This model verifies if energy is conserved around zero 
+flow when the heat flow rate is calculated from a non-linear system.
+</p>
+</html>"));
+
+end MixingVolumeNonLinSysZeroFlow;
diff --git a/Annex60/Fluid/MixingVolumes/Examples/package.order b/Annex60/Fluid/MixingVolumes/Examples/package.order
@@ -6,3 +6,4 @@ MixingVolumeMassFlow
 MixingVolumeMoistAir
 MixingVolumePrescribedHeatFlowRate
 MixingVolumeSteadyStateMass
+MixingVolumeNonLinSysZeroFlow