Corrected pressure drop calculation of solar collector (#3599)

This corrects a bug in the implementation of the solar collector pressure drop for parallel collectors. This is for #3597
lbl-srg · Dec 14, 2023 · ffc284d · ffc284d
1 parent 2585949
commit ffc284d
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Showing 7 changed files with 56 additions and 13 deletions.
diff --git a/Buildings/Fluid/SolarCollectors/ASHRAE93.mo b/Buildings/Fluid/SolarCollectors/ASHRAE93.mo
@@ -180,6 +180,13 @@ capacity of copper.
 </html>", revisions="<html>
 <ul>
 <li>
+December 11, 2023, by Michael Wetter:<br/>
+Corrected implementation of pressure drop calculation for the situation where the collectors are in parallel,
+e.g., if <code>sysConfig == Buildings.Fluid.SolarCollectors.Types.SystemConfiguration.Parallel</code>.<br/>
+This is for
+<a href=\"https://github.com/lbl-srg/modelica-buildings/issues/3597\">Buildings, #3597</a>.
+</li>
+<li>
 September 16, 2021, by Michael Wetter:<br/>
 Changed <code>lat</code> from being a parameter to an input from weather bus.<br/>
 This is for

diff --git a/Buildings/Fluid/SolarCollectors/BaseClasses/PartialSolarCollector.mo b/Buildings/Fluid/SolarCollectors/BaseClasses/PartialSolarCollector.mo
@@ -3,7 +3,7 @@ model PartialSolarCollector "Partial model for solar collectors"
  extends Buildings.Fluid.Interfaces.LumpedVolumeDeclarations;
   extends Buildings.Fluid.Interfaces.TwoPortFlowResistanceParameters(final dp_nominal = dp_nominal_final);
   extends Buildings.Fluid.Interfaces.PartialTwoPortInterface(
-    final m_flow_nominal=perPar.mperA_flow_nominal*perPar.A);
+    final m_flow_nominal=m_flow_nominal_final);
 
   constant Boolean homotopyInitialization = true "= true, use homotopy method"
     annotation(HideResult=true);
@@ -125,9 +125,14 @@ protected
     "Partial performance data"
     annotation(choicesAllMatching=true);
 
-    Modelica.Blocks.Interfaces.RealInput shaCoe_internal
+  Modelica.Blocks.Interfaces.RealInput shaCoe_internal
     "Internally used shading coefficient";
 
+  final parameter Modelica.Units.SI.MassFlowRate m_flow_nominal_final(
+      displayUnit="kg/s") = if sysConfig == Buildings.Fluid.SolarCollectors.Types.SystemConfiguration.Parallel
+     then nPanels_internal*perPar.mperA_flow_nominal*perPar.A else perPar.mperA_flow_nominal*perPar.A
+    "Nominal mass flow rate through the system of collectors";
+
   final parameter Modelica.Units.SI.PressureDifference dp_nominal_final(
       displayUnit="Pa") = if sysConfig == Buildings.Fluid.SolarCollectors.Types.SystemConfiguration.Series
      then nPanels_internal*perPar.dp_nominal else perPar.dp_nominal
@@ -242,6 +247,13 @@ CEN 2006, European Standard 12975-1:2006, European Committee for Standardization
 revisions="<html>
 <ul>
 <li>
+December 11, 2023, by Michael Wetter:<br/>
+Corrected implementation of pressure drop calculation for the situation where the collectors are in parallel,
+e.g., if <code>sysConfig == Buildings.Fluid.SolarCollectors.Types.SystemConfiguration.Parallel</code>.<br/>
+This is for
+<a href=\"https://github.com/lbl-srg/modelica-buildings/issues/3597\">Buildings, #3597</a>.
+</li>
+<li>
 September 16, 2021, by Michael Wetter:<br/>
 Changed <code>lat</code> from being a parameter to an input from weather bus.<br/>
 This is for

diff --git a/Buildings/Fluid/SolarCollectors/EN12975.mo b/Buildings/Fluid/SolarCollectors/EN12975.mo
@@ -108,6 +108,13 @@ capacity of copper.
 </html>", revisions="<html>
 <ul>
 <li>
+December 11, 2023, by Michael Wetter:<br/>
+Corrected implementation of pressure drop calculation for the situation where the collectors are in parallel,
+e.g., if <code>sysConfig == Buildings.Fluid.SolarCollectors.Types.SystemConfiguration.Parallel</code>.<br/>
+This is for
+<a href=\"https://github.com/lbl-srg/modelica-buildings/issues/3597\">Buildings, #3597</a>.
+</li>
+<li>
 September 16, 2021, by Michael Wetter:<br/>
 Changed <code>lat</code> from being a parameter to an input from weather bus.<br/>
 This is for
@@ -134,7 +141,7 @@ First implementation.
 </html>"),
       Icon(coordinateSystem(preserveAspectRatio=false, extent={{-100,-100},{100,
             100}}),
-         graphics={
+      graphics={
         Rectangle(
           extent={{-84,100},{84,-100}},
           lineColor={27,0,55},

diff --git a/Buildings/Fluid/SolarCollectors/Examples/Tubular.mo b/Buildings/Fluid/SolarCollectors/Examples/Tubular.mo
@@ -38,14 +38,15 @@ model Tubular "Example showing the use of Tubular"
   Modelica.Blocks.Sources.Sine sine(
     f=3/86400,
     offset=101325,
-    amplitude=-1.5*solCol.dp_nominal)
+    amplitude=-0.1*solCol.dp_nominal)
     annotation (Placement(transformation(extent={{-100,-20},{-80,0}})));
   Buildings.Fluid.Sources.Boundary_pT sou(
     redeclare package Medium = Medium,
     T=273.15 + 10,
     nPorts=1,
     use_p_in=true,
-    p(displayUnit="Pa")) "Inlet for water flow"                                annotation (Placement(
+    p(displayUnit="Pa")) "Inlet for water flow"
+    annotation (Placement(
         transformation(
         extent={{10,-10},{-10,10}},
         rotation=180,
@@ -92,6 +93,14 @@ equation
 revisions="<html>
 <ul>
 <li>
+December 11, 2023, by Michael Wetter:<br/>
+Changed design flow rate. This is due to correction for the
+implementation of the pressure drop calculation for the situation where collectors are in parallel,
+e.g., if <code>sysConfig == Buildings.Fluid.SolarCollectors.Types.SystemConfiguration.Parallel</code>.<br/>
+This is for
+<a href=\"https://github.com/lbl-srg/modelica-buildings/issues/3597\">Buildings, #3597</a>.
+</li>
+<li>
 September 16, 2021, by Michael Wetter:<br/>
 Removed parameter assignment for <code>lat</code>.<br/>
 This is for