Built-In Air-Cooled Chiller Curve Incorrect

[macumber]

https://openstudio.uservoice.com/forums/308629-openstudio/suggestions/16105276-built-in-air-cooled-chiller-curve-incorrect

At some point in recent versions, an air-cooled chiller object was built into the HVAC library. The issue is, one of the curves that's attached to that chiller causes the energy usage of the chiller to increase as the load on the chiller decreases. Seems like someone must have just grabbed the wrong curve when making that change.

I don't think it's important specifically what curve is used, but the curve should at least be representative of the general behavior of a chiller. I'm attaching a chart comparing the value of this curve to a couple of other standard curves. The curve in question is the Energy Input Ratio as a function of part-load ratio, which determines the fraction of rated energy use the chiller will use at a given part-load operating point.

[snlavu]

Has this been addressed in version 2.4.1?

[aaron-boranian]

Migrated from UserVoice

[kbenne]

@mpraprost We didn't go over the OS App structure, but there is an hvac library baked into the OpenStudio Application. The content is stored in osm format and it is located here https://github.com/NREL/OpenStudioApplication/blob/develop/src/openstudio_app/Resources/default/hvac_library.osm#L1417 Can you take a look at the curves and correct as needed?

Also there is a default constructor in the Model API and a curve is being defined here

OpenStudio/src/model/ChillerElectricEIR.cpp

Line 930 in da39c25

CurveBiquadratic eirToCorfOfT(model);

Please also verify that this curve data is reasonable.

[jmarrec]

This is tighly linked to #2093 and both should be investigated and fixed at the same time.