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Issue3065 dx coils performance (#3147)
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* Corrected performance calculation as a function of mass flow rates

For #3065

* Updated reference results for #3065

* Corrected function argument to ffCon

* Updated reference results
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@mwetter
mwetter committed Nov 10, 2022
1 parent 0141c99 commit 5994b61
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Showing 15 changed files with 129 additions and 102 deletions.
25 changes: 16 additions & 9 deletions Buildings/Fluid/HeatExchangers/DXCoils/BaseClasses/CoolingCapacityWaterCooled.mo
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ initial algorithm
x=1,
c=sta[iSta].perCur.capFunFFCon,
xMin=sta[iSta].perCur.ffConMin,
xMax=sta[iSta].perCur.ffConMin),
xMax=sta[iSta].perCur.ffConMax),
msg="Capacity as a function of normalized water mass flow rate at the condenser",
curveName="sta[" + String(iSta) + "].perCur.capFunFFCon");

Expand All @@ -37,7 +37,7 @@ initial algorithm
x=1,
c=sta[iSta].perCur.EIRFunFF,
xMin=sta[iSta].perCur.ffConMin,
xMax=sta[iSta].perCur.ffConMin),
xMax=sta[iSta].perCur.ffConMax),
msg="EIR as a function of normalized water mass flow rate at the condenser",
curveName="sta[" + String(iSta) + "].perCur.EIRFunFFCon");
end for;
Expand Down Expand Up @@ -65,21 +65,21 @@ if stage > 0 then
//-------------------------Cooling capacity modifiers----------------------------//

cap_FFCon[iSta] = Buildings.Fluid.Utilities.extendedPolynomial(
x=ff[iSta],
x=ffCon[iSta],
c=sta[iSta].perCur.capFunFFCon,
xMin=sta[iSta].perCur.ffConMin,
xMax=sta[iSta].perCur.ffConMin);
xMax=sta[iSta].perCur.ffConMax);
//-----------------------Energy Input Ratio modifiers--------------------------//
EIR_FFCon[iSta] = Buildings.Fluid.Utilities.extendedPolynomial(
x=ff[iSta],
x=ffCon[iSta],
c=sta[iSta].perCur.EIRFunFFCon,
xMin=sta[iSta].perCur.ffConMin,
xMax=sta[iSta].perCur.ffConMin)
xMax=sta[iSta].perCur.ffConMax)
"Cooling capacity modification factor as function of flow fraction";
//------------ Correction factor for flow rate outside of validity of data ---//
corFacCon[iSta] =Buildings.Utilities.Math.Functions.smoothHeaviside(
x=ffCon[iSta] - sta[iSta].perCur.ffConMin/4,
delta=max(Modelica.Constants.eps, sta[iSta].perCur.ffConMin/4));
delta=max(Modelica.Constants.eps, sta[iSta].perCur.ffConMin/8));

Q_flow[iSta] = corFac[iSta]*corFacCon[iSta]*cap_T[iSta]*cap_FF[iSta]*cap_FFCon[iSta]*sta[iSta].nomVal.Q_flow_nominal;
EIR[iSta] = corFac[iSta]*corFacCon[iSta]*EIR_T[iSta]*EIR_FF[iSta]*EIR_FFCon[iSta]/sta[iSta].nomVal.COP_nominal;
Expand Down Expand Up @@ -147,15 +147,22 @@ if stage > 0 then
revisions="<html>
<ul>
<li>
February 17, 2017 by Yangyang Fu:<br/>
First implementation.
November 8, 2022, by Michael Wetter:<br/>
Corrected calculation of performance which used the wrong upper bound, and
which used <code>ff</code> instead of <code>ffCon</code> for calculating <code>cap_FFCon</code>.<br/>
This is for
<a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/3146\">issue 3146</a>.
</li>
<li>
October 21, 2019, by Michael Wetter:<br/>
Ensured that transition interval for computation of <code>corFac</code> is non-zero.<br/>
This is for
<a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/1202\">issue 1202</a>.
</li>
<li>
February 17, 2017 by Yangyang Fu:<br/>
First implementation.
</li>
</ul>

</html>"));
Expand Down
16 changes: 11 additions & 5 deletions Buildings/Fluid/HeatExchangers/DXCoils/BaseClasses/PartialCoolingCapacity.mo
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Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,7 @@ initial algorithm
x=1,
c=sta[iSta].perCur.capFunFF,
xMin=sta[iSta].perCur.ffMin,
xMax=sta[iSta].perCur.ffMin),
xMax=sta[iSta].perCur.ffMax),
msg="Capacity as a function of normalized mass flow rate ",
curveName="sta[" + String(iSta) + "].perCur.capFunFF");

Expand All @@ -107,7 +107,7 @@ initial algorithm
x=1,
c=sta[iSta].perCur.EIRFunFF,
xMin=sta[iSta].perCur.ffMin,
xMax=sta[iSta].perCur.ffMin),
xMax=sta[iSta].perCur.ffMax),
msg="EIR as a function of normalized mass flow rate ",
curveName="sta[" + String(iSta) + "].perCur.EIRFunFF");
end for;
Expand Down Expand Up @@ -183,7 +183,7 @@ if stage > 0 then
x=ff[iSta],
c=sta[iSta].perCur.capFunFF,
xMin=sta[iSta].perCur.ffMin,
xMax=sta[iSta].perCur.ffMin);
xMax=sta[iSta].perCur.ffMax);
//-----------------------Energy Input Ratio modifiers--------------------------//
EIR_T[iSta] =Buildings.Utilities.Math.Functions.smoothMax(
x1=Buildings.Utilities.Math.Functions.biquadratic(
Expand All @@ -196,12 +196,12 @@ if stage > 0 then
x=ff[iSta],
c=sta[iSta].perCur.EIRFunFF,
xMin=sta[iSta].perCur.ffMin,
xMax=sta[iSta].perCur.ffMin)
xMax=sta[iSta].perCur.ffMax)
"Cooling capacity modification factor as function of flow fraction";
//------------ Correction factor for flow rate outside of validity of data ---//
corFac[iSta] =Buildings.Utilities.Math.Functions.smoothHeaviside(
x=ff[iSta] - sta[iSta].perCur.ffMin/4,
delta=max(Modelica.Constants.eps, sta[iSta].perCur.ffMin/4));
delta=max(Modelica.Constants.eps, sta[iSta].perCur.ffMin/8));

end for;
else //cooling coil off
Expand Down Expand Up @@ -400,6 +400,12 @@ so that both are zero if <i>ff &lt; ff<sub>min</sub>/4</i>, where
revisions="<html>
<ul>
<li>
November 8, 2022, by Michael Wetter:<br/>
Corrected calculation of performance which used the wrong upper bound.<br/>
This is for
<a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/3146\">issue 3146</a>.
</li>
<li>
October 21, 2019, by Michael Wetter:<br/>
Ensured that transition interval for computation of <code>corFac</code> is non-zero.<br/>
This is for
Expand Down
18 changes: 9 additions & 9 deletions ...Dymola/Buildings_Applications_DataCenters_DXCooled_Examples_DXCooledAirsideEconomizer.txt
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