CU to Review Scaling Factors

[laurenklun]

wait until Antione is back

[Helarga]

• time series model with modifications to avoid the trial and error approach implemented to set the correct facScaHea and facScaCoo https://github.com/Helarga/modelica-buildings/blob/issue1437_district_heating_cooling/Buildings/Applications/DHC/Loads/Examples/BaseClasses/BuildingTimeSeriesHE.mo

• example 1 ( the same example developed by LBL but with a facScaHea = facScaHea=1) https://github.com/Helarga/modelica-buildings/blob/issue1437_district_heating_cooling/Buildings/Applications/DHC/Loads/Examples/CouplingTimeSeriesHE.mo

• example 2 ( time series simultaneous heating and cooling loads generated by OS ) https://github.com/Helarga/modelica-buildings/blob/issue1437_district_heating_cooling/Buildings/Applications/DHC/Loads/Examples/TimeSeriesOpenStudioSimultaneousHeatingCooling.mo

[JingWang-CUB]

@Helarga Thank you for sending the models for us to review. After reviewing the BuildingTimeSeriesHE model, I have a few questions and comments. Please see below.

1. I understand that you set the scaling factors for both heating and cooling to 1 and use cp_air and deltaT for mass flow rate calculation instead. This seems to be a good approach. Could you please remind me why originally scaling factors were needed?

2. cp_air should be an inner parameter that's calculated depending on the state of the medium (air).

Otherwise, the model looks good to me. Thanks!

[Helarga]

@Helarga Thank you for sending the models for us to review. After reviewing the BuildingTimeSeriesHE model, I have a few questions and comments. Please see below.

1. I understand that you set the scaling factors for both heating and cooling to 1 and use cp_air and deltaT for mass flow rate calculation instead. This seems to be a good approach. Could you please remind me why originally scaling factors were needed?

please, check the original models in
Buildings.Applications.DHC.Loads.Examples.CouplingTimeSeries and Buildings.Applications.DHC.Loads.Examples.BaseClasses.BuildingTimeSeries if there is something not clear for you, contact me

2. cp_air should be an inner parameter that's calculated depending on the state of the medium (air).

no it shouldn't, the cp_air parameter = 1.005kJ/kgK is a very good nominal specific heat capacity value for nominal air temperature of heating =20degC and cooling =24degC..

https://www.ohio.edu/mechanical/thermo/property_tables/air/air_Cp_Cv.html#:~:text=The%20nominal%20values%20used%20for,one%20can%20obtain%20significant%20errors.

you can also run this nice model at the MBL and check how the cp value change with air temperature Buildings.Media.Examples.AirDerivativeCheck

you can also find that, specific heat capacity is evaluated as constant =1006 in Buildings.Utilities.Psychrometrics.Constants and used here Buildings.Air.Systems.SingleZone.VAV.ChillerDXHeatingEconomizer and here also Buildings.Controls.OBC.CDL.Psychrometrics.h_TDryBulPhi

Otherwise, the model looks good to me. Thanks!

[nllong]

Hi @JingWang-CUB -- thanks for reviewing. When you are updating the partial building models per our other discussions can you also update the scaling factor as recommended?

[JingWang-CUB]

Hi @nllong , the two versions seem to be just different ways of model design. Should we also get @JayHuLBL 's feedback and agree on one version of the BuildingTimeSeries model? Thank you!