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Merge pull request #1834 from ibpsa/issue1830_redundantInitialConditions
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Changed example to avoid redundant initial conditions
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@mwetter
mwetter authored Feb 7, 2024
2 parents 698e04d + 8c78453 commit 14b370d
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Showing 2 changed files with 47 additions and 32 deletions.
59 changes: 39 additions & 20 deletions IBPSA/Fluid/Sensors/Examples/PPM.mo
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@ model PPM "Test model for the extra property sensor outputting PPM"
package Medium = IBPSA.Media.Air(extraPropertiesNames={"CO2"})
"Medium model";

parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=volDyn.V*
senPPMTwoPort.tau*3*rho_default
parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=
volDyn.V*senPPMTwoPort.tau*3*rho_default
"Mass flow rate into and out of the volume";

IBPSA.Fluid.MixingVolumes.MixingVolume volDyn(
Expand All @@ -20,7 +20,7 @@ model PPM "Test model for the extra property sensor outputting PPM"
redeclare package Medium = Medium,
nPorts=2,
m_flow=m_flow_nominal) "Fresh air supply"
annotation (Placement(transformation(extent={{-40,30},{-20,50}})));
annotation (Placement(transformation(origin = {-28, 0}, extent = {{-40, 30}, {-20, 50}})));

IBPSA.Fluid.Sensors.PPM senPPMVol(
redeclare package Medium = Medium,
Expand Down Expand Up @@ -82,32 +82,44 @@ model PPM "Test model for the extra property sensor outputting PPM"
redeclare package Medium = Medium,
nPorts=1,
m_flow=m_flow_nominal) "Fresh air supply for steady state volume"
annotation (Placement(transformation(extent={{-40,110},{-20,130}})));
annotation (Placement(transformation(origin = {-28, 0}, extent = {{-40, 110}, {-20, 130}})));
IBPSA.Fluid.Sources.Boundary_pT sin(
redeclare package Medium = Medium,
nPorts=2) "Exhaust air"
annotation (Placement(transformation(extent={{-40,-60},{-20,-40}})));
annotation (Placement(transformation(origin = {-30, 0}, extent = {{-40, -60}, {-20, -40}})));

IBPSA.Fluid.FixedResistances.PressureDrop dp(
redeclare package Medium = Medium,
dp_nominal = 200,
m_flow_nominal = m_flow_nominal)
"Pressure drop to decouple volume pressure from boundary pressure"
annotation (
Placement(transformation(origin = {-28, -50}, extent = {{-2, -10}, {18, 10}})));

protected
final parameter Medium.ThermodynamicState state_default = Medium.setState_pTX(
T=Medium.T_default,
p=Medium.p_default,
X=Medium.X_default[1:Medium.nXi]) "Medium state at default values";
X=Medium.X_default[1:Medium.nXi]) "Medium state at default values"
annotation(Evaluate=true);
// Density at medium default values, used to compute the size of control volumes
final parameter Modelica.Units.SI.Density rho_default=Medium.density(state=
state_default) "Density, used to compute fluid mass";
final parameter Modelica.Units.SI.Density rho_default=Medium.density(
state=state_default)
"Density, used to compute fluid mass"
annotation(Evaluate=true);

equation
connect(mSou.ports[1], volDyn.ports[1]) annotation (Line(points={{-20,42},{
77.3333,42},{77.3333,50}}, color={0,127,255}));
connect(mSou.ports[1], volDyn.ports[1]) annotation (Line(points={{-48,39},{
-48,50},{78.6667,50}},
color={0,127,255}));
connect(CO2In.y, volDyn.C_flow[1]) annotation (Line(points={{21,70},{32,70},{32,
54},{68,54}}, color={0,0,127}));
connect(senPPMVol.port, volDyn.ports[2]) annotation (Line(points={{130,40},{80,
40},{80,50}}, color={0,127,255}));
40},{80,50}},color={0,127,255}));
connect(senPPMIn.port, mSou.ports[2])
annotation (Line(points={{-10,80},{-10,38},{-20,38}}, color={0,127,255}));
annotation (Line(points={{-10,80},{-10,41},{-48,41}}, color={0,127,255}));
connect(senPPMTwoPort.port_a, volDyn.ports[3]) annotation (Line(points={{80,20},
{80,50},{82.6667,50}}, color={0,127,255}));
{80,50},{81.3333,50}}, color={0,127,255}));
connect(senPPMNoRev.port_a, senPPMTwoPort.port_b)
annotation (Line(points={{80,-20},{80,0}}, color={0,127,255}));
connect(senPPMRev.port_b, senPPMNoRev.port_b) annotation (Line(points={{60,-50},
Expand All @@ -116,15 +128,17 @@ equation
annotation (Line(points={{20,-50},{30,-50},{40,-50}}, color={0,127,255}));
connect(CO2In.y,volSte. C_flow[1]) annotation (Line(points={{21,70},{32,70},{32,
84},{68,84}}, color={0,0,127}));
connect(volSte.ports[1], senPPMVol2.port) annotation (Line(points={{77.3333,
connect(volSte.ports[1], senPPMVol2.port) annotation (Line(points={{78.6667,
80},{130,80}}, color={0,127,255}));
connect(mSouSta.ports[1], volSte.ports[2]) annotation (Line(points={{-20,120},
connect(mSouSta.ports[1], volSte.ports[2]) annotation (Line(points={{-48,120},
{54,120},{54,80},{80,80}}, color={0,127,255}));
connect(sin.ports[1], senPPMSta.port_b) annotation (Line(points={{-20,-48},{-10,
-48},{-10,-50},{0,-50}}, color={0,127,255}));
connect(sin.ports[2], volSte.ports[3]) annotation (Line(points={{-20,-52},{
-20,-80},{110,-80},{110,80},{82.6667,80}},
color={0,127,255}));
connect(sin.ports[1], volSte.ports[3]) annotation (
Line(points={{-50,-51},{-50,-80},{110,-80},{110,80},{81.3333,80}}, color = {0, 127, 255}));
connect(dp.port_b, senPPMSta.port_b) annotation (
Line(points = {{-10, -50}, {0, -50}}, color = {0, 127, 255}));
connect(dp.port_a, sin.ports[2]) annotation (
Line(points={{-30,-50},{-40,-50},{-40,-49},{-50,-49}},
color = {0, 127, 255}));
annotation (
experiment(Tolerance=1e-6, StopTime=3),
__Dymola_Commands(file="modelica://IBPSA/Resources/Scripts/Dymola/Fluid/Sensors/Examples/PPM.mos"
Expand All @@ -142,6 +156,11 @@ and with or without dynamics are tested.
revisions="<html>
<ul>
<li>
February 1, 2024, by Michael Wetter:<br/>
Added pressure drop to avoid redundant initial conditions for pressure of control volume.<br/>
This is for <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/1830\"> #1830</a>.
</li>
<li>
May 2, 2019, by Jianjun Hu:<br/>
Replaced fluid source. This is for
<a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/1072\"> #1072</a>.
Expand Down
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