ibpsa · mwetter · Apr 8, 2026 · Apr 1, 2026 · Apr 1, 2026 · Apr 1, 2026
diff --git a/IBPSA/Fluid/Actuators/BaseClasses/PartialTwoWayValve.mo b/IBPSA/Fluid/Actuators/BaseClasses/PartialTwoWayValve.mo
@@ -22,7 +22,7 @@ partial model PartialTwoWayValve "Partial model for a two way valve"
   parameter Real kFixed(unit="", min=0) = if dpFixed_nominal > Modelica.Constants.eps
     then m_flow_nominal / sqrt(dpFixed_nominal) else 0
     "Flow coefficient of fixed resistance that may be in series with valve, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2).";
-  Real kVal(unit="1", min=Modelica.Constants.small)
+  Real kVal(unit="", min=Modelica.Constants.small)
     "Flow coefficient of valve, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2).";
   Real k(unit="", min=Modelica.Constants.small)
     "Flow coefficient of valve and pipe in series, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2).";
@@ -97,6 +97,11 @@ each valve opening characteristics has different parameters.
 revisions="<html>
 <ul>
 <li>
+March 31, 2026, by Michael Wetter:<br/>
+Corrected unit propagation error that causes Dymola 2026x to not show certain units.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2100\">#2100</a>.
+</li>
+<li>
 January 19, 2026, by Jelger Jansen:<br/>
 Added unit 1 to parameter <code>kVal</code> to avoid FMU unit errors.<br/>
 This is for <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2074\">#2074</a>.

diff --git a/IBPSA/Fluid/Examples/Performance/BaseClasses/Example1.mo b/IBPSA/Fluid/Examples/Performance/BaseClasses/Example1.mo
@@ -29,7 +29,10 @@ partial model Example1 "Example 1 partial model"
     annotation (Placement(transformation(extent={{-20,20},{0,40}})));
   Modelica.Blocks.Sources.Pulse pulse(period=1000) "Pulse input"
     annotation (Placement(transformation(extent={{-60,70},{-40,90}})));
-  Modelica.Blocks.Math.Gain gain(k=m_flow_nominal) "Gain for m_flow_nominal"
+  Modelica.Blocks.Math.Gain gain(
+    k=m_flow_nominal,
+    u(unit="1"),
+    y(unit="kg/s")) "Gain for m_flow_nominal"
     annotation (Placement(transformation(extent={{0,70},{20,90}})));
   IBPSA.Fluid.Actuators.Valves.ThreeWayLinear val(
     redeclare package Medium = Medium,
@@ -109,6 +112,11 @@ and is created to avoid errors in the implementation of the two depending exampl
 </html>", revisions="<html>
 <ul>
 <li>
+March 31, 2026, by Michael Wetter:<br/>
+Corrected unit propagation error that causes Dymola 2026x to not show certain units.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2100\">#2100</a>.
+</li>
+<li>
 May 8, 2017, by Michael Wetter:<br/>
 Updated heater model.<br/>
 This is for

diff --git a/IBPSA/Fluid/Examples/ResistanceVolumeFlowReversal.mo b/IBPSA/Fluid/Examples/ResistanceVolumeFlowReversal.mo
@@ -28,7 +28,10 @@ model ResistanceVolumeFlowReversal
     annotation (Placement(transformation(extent={{-40,-30},{-20,-10}})));
   Modelica.Blocks.Sources.Pulse pulse(period=1000) "Pulse input"
     annotation (Placement(transformation(extent={{-80,40},{-60,60}})));
-  Modelica.Blocks.Math.Gain gain(k=m_flow_nominal) "Gain for m_flow_nominal"
+  Modelica.Blocks.Math.Gain gain(
+    k=m_flow_nominal,
+    u(unit="1"),
+    y(unit="kg/s")) "Gain for m_flow_nominal"
     annotation (Placement(transformation(extent={{-40,40},{-20,60}})));
   IBPSA.Fluid.Actuators.Valves.ThreeWayLinear val(
     redeclare package Medium = Medium,
@@ -103,7 +106,6 @@ equation
                                           color={0,127,255}));
     connect(senTem[i].port_b, val.port_3) annotation (Line(
        points={{10,-70},{0,-70},{0,-30}}, color={0,127,255}));
-
   end for;
 
   annotation (experiment(
@@ -164,6 +166,11 @@ Sizes after manipulation of the nonlinear systems: {1, 9, <b>1</b>}
 </html>", revisions="<html>
 <ul>
 <li>
+March 31, 2026, by Michael Wetter:<br/>
+Corrected unit propagation error that causes Dymola 2026x to not show certain units.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2100\">#2100</a>.
+</li>
+<li>
 July 18, 2025, by Hongxiang Fu:<br/>
 Added two-port temperature sensors to replace <code>vol[:].T</code>
 from reference results.<br/>

diff --git a/IBPSA/Fluid/FixedResistances/PressureDrop.mo b/IBPSA/Fluid/FixedResistances/PressureDrop.mo
@@ -21,10 +21,13 @@ protected
     (dp_nominal_pos > Modelica.Constants.eps) and not disableComputeFlowResistance_internal
     "Flag to enable/disable computation of flow resistance"
    annotation(Evaluate=true);
-  final parameter Real coeff=
+  final parameter Real coeM(final unit="kg/(s.Pa)")=
     if linearized and computeFlowResistance
-    then if from_dp then k^2/m_flow_nominal_pos else m_flow_nominal_pos/k^2
-    else 0
+    then k^2/m_flow_nominal_pos else 0
+    "Precomputed coefficient to avoid division by parameter";
+  final parameter Real coeP(final unit="s.Pa/kg")=
+    if linearized and computeFlowResistance
+    then m_flow_nominal_pos/k^2 else 0
     "Precomputed coefficient to avoid division by parameter";
 initial equation
  if computeFlowResistance then
@@ -37,9 +40,9 @@ equation
   if computeFlowResistance then
     if linearized then
       if from_dp then
-        m_flow = dp*coeff;
+        m_flow = dp*coeM;
       else
-        dp = m_flow*coeff;
+        dp = m_flow*coeP;
       end if;
     else
       if homotopyInitialization then
@@ -184,6 +187,11 @@ This leads to simpler equations.
 </html>", revisions="<html>
 <ul>
 <li>
+March 31, 2026, by Michael Wetter:<br/>
+Corrected unit propagation error that causes Dymola 2026x to not show certain units.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2100\">#2100</a>.
+</li>
+<li>
 April 25, 2025, by Fabian Wuelhorst and Michael Wetter:<br/>
 Add option to disable <code>computeFlowResistance</code> for extending classes.<br/>
 See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2001\">#2001</a>.

diff --git a/.../BaseClasses/HeatTransfer/ThermalResponseFactors/Validation/FiniteLineSource_Integrand.mo b/.../BaseClasses/HeatTransfer/ThermalResponseFactors/Validation/FiniteLineSource_Integrand.mo
@@ -11,11 +11,12 @@ model FiniteLineSource_Integrand
   parameter Modelica.Units.SI.Height len2=150.0 "Length of receiving borehole";
   parameter Modelica.Units.SI.Height burDep2=4.0
     "Buried depth of receiving borehole";
-  Real u "Integration variable";
+  Real u(unit="1/m") "Integration variable";
   Real y "Finite line source integrand";
+  constant Real con(unit="1/(m.s)") = 1 "Unit conversion factor";
 
 equation
-  u = time;
+  u = con*time;
   y = IBPSA.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_Integrand(
     u=u,
     dis=dis,
@@ -37,6 +38,11 @@ finite line source integrand function.
 </html>", revisions="<html>
 <ul>
 <li>
+March 31, 2026, by Michael Wetter:<br/>
+Corrected unit propagation error that causes Dymola 2026x to not show certain units.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2100\">#2100</a>.
+</li>
+<li>
 July 17, 2018, by Massimo Cimmino:<br/>
 First implementation.
 </li>

diff --git a/...s/HeatTransfer/ThermalResponseFactors/Validation/FiniteLineSource_Integrand_Equivalent.mo b/...s/HeatTransfer/ThermalResponseFactors/Validation/FiniteLineSource_Integrand_Equivalent.mo
@@ -18,13 +18,14 @@ model FiniteLineSource_Integrand_Equivalent
   parameter Integer nBor2=3 "Number of receiving lines";
   parameter Integer n_dis=2 "Number of unique distances";
 
-  Real u "Integration variable";
+  Real u(unit="1/m") "Integration variable";
   Real yRea "Finite line source integrand (Real part)";
   Real yMir "Finite line source integrand (Mirror part)";
   Real y "Finite line source integrand";
+  constant Real con(unit="1/(m.s)") = 1 "Unit conversion factor";
 
 equation
-  u = time;
+  u = con*time;
   yRea =
     IBPSA.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_Integrand_Equivalent(
     u=u,
@@ -76,6 +77,11 @@ with coordinates (x,y) = {(0,0), (0,7), (7,0)}.
 </html>", revisions="<html>
 <ul>
 <li>
+March 31, 2026, by Michael Wetter:<br/>
+Corrected unit propagation error that causes Dymola 2026x to not show certain units.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2100\">#2100</a>.
+</li>
+<li>
 June 9, 2022, by Massimo Cimmino:<br/>
 First implementation.
 </li>

diff --git a/...asses/HeatTransfer/ThermalResponseFactors/Validation/FiniteLineSource_Integrand_Length.mo b/...asses/HeatTransfer/ThermalResponseFactors/Validation/FiniteLineSource_Integrand_Length.mo
@@ -12,14 +12,16 @@ model FiniteLineSource_Integrand_Length
   parameter Modelica.Units.SI.Height len1=1.0 "Length of emitting borehole";
   parameter Modelica.Units.SI.Height burDep=4.
     "Buried depth of emitting borehole";
-  Real u "Integration variable";
+  Real u(unit="1/m") "Integration variable";
+  constant Real con(unit="1/(m.s)") = 1 "Unit conversion factor";
+
   Real logy150 "Logarithm of finite line source integrand";
   Real logy75 "Logarithm of finite line source integrand";
   Real logy25 "Logarithm of finite line source integrand";
   Real logy5 "Logarithm of finite line source integrand";
   Real logy1 "Logarithm of finite line source integrand";
 equation
-  u = time;
+  u = con*time;
   logy150 = log10(max(small,
     IBPSA.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_Integrand(
       u=u,
@@ -74,6 +76,11 @@ finite line source integrand function.
 </html>", revisions="<html>
 <ul>
 <li>
+March 31, 2026, by Michael Wetter:<br/>
+Corrected unit propagation error that causes Dymola 2026x to not show certain units.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2100\">#2100</a>.
+</li>
+<li>
 September 15, 2025, by Michael Wetter:<br/>
 Changed value of small number that bounds log10.<br/>
 This is for

diff --git a/IBPSA/Fluid/HeatExchangers/WetCoilEffectivenessNTU.mo b/IBPSA/Fluid/HeatExchangers/WetCoilEffectivenessNTU.mo
@@ -78,6 +78,9 @@ model WetCoilEffectivenessNTU
     "Dry fraction, 0.3 means condensation occurs at 30% heat exchange length from air inlet";
 
 protected
+  constant Real kUniConHeaCoo(final unit="1/W") = 1 "Constant for unit conversion";
+  constant Real kUniConHum(final unit="s/kg") = 1 "Constant for unit conversion";
+
   final parameter Modelica.Units.SI.MassFraction X_w_a2_nominal=w_a2_nominal/(1
        + w_a2_nominal)
     "Water mass fraction of inlet air at a rated condition (in kg/kg total air)";
@@ -122,8 +125,7 @@ protected
     final dp_nominal = dp1_nominal,
     final m_flow_nominal = m1_flow_nominal,
     final energyDynamics = energyDynamics,
-    final Q_flow_nominal=-1,
-    u(final unit="W"))
+    final Q_flow_nominal=-1)
     "Heat exchange with water stream"
     annotation (Placement(transformation(extent={{60,50},{80,70}})));
 
@@ -132,10 +134,9 @@ protected
     final mWat_flow_nominal = 1,
     final dp_nominal = dp2_nominal,
     final m_flow_nominal = m2_flow_nominal,
-    final energyDynamics = energyDynamics,
-    u(final unit="kg/s"))
+    final energyDynamics = energyDynamics)
     "Heat and moisture exchange with air stream"
-    annotation (Placement(transformation(extent={{-60,-70},{-80,-50}})));
+    annotation (Placement(transformation(extent={{-62,-94},{-82,-74}})));
   IBPSA.Fluid.HeatExchangers.BaseClasses.HADryCoil hA(
     final UA_nominal = UA_nominal,
     final m_flow_nominal_a = m2_flow_nominal,
@@ -224,7 +225,7 @@ protected
 
   Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow preHea
     "Prescribed heat flow"
-    annotation (Placement(transformation(extent={{20,-90},{0,-70}})));
+    annotation (Placement(transformation(extent={{18,-100},{-2,-80}})));
   Real fra_a1(min=0, max=1) = if allowFlowReversal1
     then Modelica.Fluid.Utilities.regStep(
       m1_flow,
@@ -281,6 +282,13 @@ protected
      p=Medium2.p_default,
      X=Medium2.X_default[1:Medium2.nXi]) "Default state for medium 2";
 
+  Modelica.Blocks.Math.Gain uniConHum(
+    final k=kUniConHum) "Unit conversion for input to humidifier"
+    annotation (Placement(transformation(extent={{-20,-70},{-40,-50}})));
+  Modelica.Blocks.Math.Gain uniConHeaCoo(
+    final k=kUniConHeaCoo)
+    "Unit conversion for input to heater and cooler model"
+    annotation (Placement(transformation(extent={{12,70},{32,90}})));
 initial equation
   assert(m1_flow_nominal > Modelica.Constants.eps,
     "m1_flow_nominal must be positive, m1_flow_nominal = " + String(
@@ -368,36 +376,34 @@ equation
   connect(heaCoo.port_b, port_b1) annotation (Line(points={{80,60},{80,60},{100,60}},color={0,127,255},
       thickness=1));
   connect(heaCooHum_u.port_b, port_b2) annotation (Line(
-      points={{-80,-60},{-90,-60},{-100,-60}},
+      points={{-82,-84},{-90,-84},{-90,-60},{-100,-60}},
       color={0,127,255},
       thickness=1));
   connect(hA.hA_1, dryWetCalcs.UAWat) annotation (Line(points={{-49.1,5.7},{-46,
           5.7},{-46,36.6667},{-22.8571,36.6667}},  color={0,0,127}));
-  connect(hA.hA_2, dryWetCalcs.UAAir) annotation (Line(points={{-49.1,-9.7},{
-          -46,-9.7},{-46,-36},{-46,-36.6667},{-22.8571,-36.6667}},
+  connect(hA.hA_2, dryWetCalcs.UAAir) annotation (Line(points={{-49.1,-9.7},{-46,
+          -9.7},{-46,-36},{-46,-36.6667},{-22.8571,-36.6667}},
                                                      color={0,0,127}));
-  connect(cp_a1Exp.y, dryWetCalcs.cpWat) annotation (Line(points={{-29.3,24},{
-          -22.8571,24},{-22.8571,23.3333}},
-                                   color={0,0,127}));
+  connect(cp_a1Exp.y, dryWetCalcs.cpWat) annotation (Line(points={{-29.3,24},{-22.8571,
+          24},{-22.8571,23.3333}}, color={0,0,127}));
   connect(XWat_a2Exp.y, dryWetCalcs.X_wAirIn) annotation (Line(points={{-29.3,4},
           {-22.8571,4},{-22.8571,3.33333}},  color={0,0,127}));
-  connect(p_a2Exp.y, dryWetCalcs.pAir) annotation (Line(points={{-29.3,-4},{
-          -22.8571,-4},{-22.8571,-3.33333}},
+  connect(p_a2Exp.y, dryWetCalcs.pAir) annotation (Line(points={{-29.3,-4},{-22.8571,
+          -4},{-22.8571,-3.33333}},
                                   color={0,0,127}));
-  connect(h_a2Exp.y, dryWetCalcs.hAirIn) annotation (Line(points={{-29.3,-12},{
-          -22,-12},{-22,-10},{-22.8571,-10}},
+  connect(h_a2Exp.y, dryWetCalcs.hAirIn) annotation (Line(points={{-29.3,-12},{-22,
+          -12},{-22,-10},{-22.8571,-10}},
                                     color={0,0,127}));
-  connect(cp_a2Exp.y, dryWetCalcs.cpAir) annotation (Line(points={{-29.3,-24},{
-          -22.8571,-24},{-22.8571,-23.3333}},
-                                     color={0,0,127}));
+  connect(cp_a2Exp.y, dryWetCalcs.cpAir) annotation (Line(points={{-29.3,-24},{-22.8571,
+          -24},{-22.8571,-23.3333}}, color={0,0,127}));
   connect(TIn_a1Exp.y, hA.T_1) annotation (Line(points={{-83.3,22},{-80,22},{-80,
           1.3},{-68.9,1.3}},       color={0,0,127}));
-  connect(TIn_a1Exp.y, dryWetCalcs.TWatIn) annotation (Line(points={{-83.3,22},
-          {-50,22},{-50,16.6667},{-22.8571,16.6667}}, color={0,0,127}));
+  connect(TIn_a1Exp.y, dryWetCalcs.TWatIn) annotation (Line(points={{-83.3,22},{
+          -50,22},{-50,16.6667},{-22.8571,16.6667}},  color={0,0,127}));
   connect(TIn_a2Exp.y, hA.T_2) annotation (Line(points={{-83.3,-2},{-76,-2},{-76,
           -5.3},{-68.9,-5.3}},   color={0,0,127}));
-  connect(TIn_a2Exp.y, dryWetCalcs.TAirIn) annotation (Line(points={{-83.3,-2},
-          {-76,-2},{-76,-16.6667},{-22.8571,-16.6667}}, color={0,0,127}));
+  connect(TIn_a2Exp.y, dryWetCalcs.TAirIn) annotation (Line(points={{-83.3,-2},{
+          -76,-2},{-76,-16.6667},{-22.8571,-16.6667}},  color={0,0,127}));
   connect(m_flow_a1Exp.y, hA.m1_flow) annotation (Line(points={{-83.3,36},{-76,36},
           {-76,5.7},{-68.9,5.7}},       color={0,0,127}));
   connect(m_flow_a1Exp.y, dryWetCalcs.mWat_flow) annotation (Line(points={{-83.3,
@@ -412,19 +418,21 @@ equation
   connect(m_flow_a2Exp.y, dryWetCalcs.mAir_flow) annotation (Line(points={{-83.3,
           -30},{-22.8571,-30}},                      color={0,0,127}));
   connect(port_a2, heaCooHum_u.port_a) annotation (Line(
-      points={{100,-60},{20,-60},{-60,-60}},
+      points={{100,-60},{72,-60},{72,-76},{-52,-76},{-52,-84},{-62,-84}},
       color={0,127,255},
       thickness=1));
-  connect(preHea.port, heaCooHum_u.heatPort) annotation (Line(points={{0,-80},{-40,
-          -80},{-40,-66},{-60,-66}}, color={191,0,0}));
-  connect(dryWetCalcs.QTot_flow, heaCoo.u) annotation (Line(points={{62.8571,
-          -6.66667},{80,-6.66667},{80,44},{40,44},{40,66},{58,66}},
-                                                          color={0,0,127}));
-  connect(dryWetCalcs.mCon_flow, heaCooHum_u.u) annotation (Line(points={{62.8571,
-          -33.3333},{70,-33.3333},{70,-54},{-59,-54}}, color={0,0,127}));
-  connect(preHea.Q_flow, dryWetCalcs.QTot_flow) annotation (Line(points={{20,-80},
-          {44,-80},{80,-80},{80,-6.66667},{62.8571,-6.66667}},
-                                                           color={0,0,127}));
+  connect(preHea.port, heaCooHum_u.heatPort) annotation (Line(points={{-2,-90},{
+          -62,-90}},                 color={191,0,0}));
+  connect(preHea.Q_flow, dryWetCalcs.QTot_flow) annotation (Line(points={{18,-90},
+          {80,-90},{80,-6.66667},{62.8571,-6.66667}},      color={0,0,127}));
+  connect(dryWetCalcs.mCon_flow, uniConHum.u) annotation (Line(points={{62.8571,
+          -33.3333},{70,-33.3333},{70,-60},{-18,-60}}, color={0,0,127}));
+  connect(uniConHum.y, heaCooHum_u.u) annotation (Line(points={{-41,-60},{-56,-60},
+          {-56,-78},{-61,-78}}, color={0,0,127}));
+  connect(dryWetCalcs.QTot_flow, uniConHeaCoo.u) annotation (Line(points={{62.8571,
+          -6.66667},{80,-6.66667},{80,44},{4,44},{4,80},{10,80}}, color={0,0,127}));
+  connect(uniConHeaCoo.y, heaCoo.u) annotation (Line(points={{33,80},{48,80},{48,
+          66},{58,66}}, color={0,0,127}));
   annotation (
     defaultComponentName="hexWetNtu",
     Icon(graphics={
@@ -522,7 +530,7 @@ equation
           fillPattern=FillPattern.Solid,
           smooth=Smooth.Bezier)}),
         Diagram(graphics={Text(
-          extent={{44,84},{86,76}},
+          extent={{-80,70},{-38,62}},
           textColor={28,108,200},
           textString="Water Side",
           textStyle={TextStyle.Italic},
@@ -650,6 +658,11 @@ Fuzzy identification of systems and its applications to modeling and control.
 </html>",                    revisions="<html>
 <ul>
 <li>
+March 31, 2026, by Michael Wetter:<br/>
+Corrected unit propagation error that causes Dymola 2026x to not show certain units.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2100\">#2100</a>.
+</li>
+<li>
 February 7, 2025, by Jelger Jansen:<br/>
 Removed <code>import</code> statement.
 This is for