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set start value for NTUAirSta in WetCoilWetRegime #1728

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mwetter opened this issue Apr 18, 2023 · 0 comments · Fixed by #1729
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set start value for NTUAirSta in WetCoilWetRegime #1728

mwetter opened this issue Apr 18, 2023 · 0 comments · Fixed by #1729
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mwetter commented Apr 18, 2023

The model Fluid/HeatExchangers/BaseClasses/WetCoilWetRegime.mo has an expression

  hSatSurEff = IBPSA.Utilities.Math.Functions.smoothMax(
    x1 = hSatSurEffMinM.hSat,
    x2 = hAirIn  +(hAirOut - hAirIn) / (1 - exp(-NTUAirSta)),
    deltaX = delta*1E4); // NTUAirSta is bounded as long as UAAir>0 due to the regularization of mAir_flow

In OpenModelica, in some models such as Buildings.Fluid.HydronicConfigurations.PassiveNetworks.Examples.SingleMixingOpenLoop, NTUAirSta has 0 at the start of an iteration which causes a division by zero.

Setting a start value of 1 to NTUAirSta avoids this issue.
@mwetter mwetter self-assigned this Apr 18, 2023
mwetter added a commit that referenced this issue Apr 18, 2023
@mwetter
Set start value
9006845 
For #1728
@mwetter mwetter mentioned this issue Apr 18, 2023
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Set start value for NTU in WetCoilWetRegime ibpsa/modelica-ibpsa
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@mwetter