[Bldg-sim] Requesting chiller performance data

[Kyle Fridgen via Bldg-sim]

Hi Modellers,

In EnergyPlus, we are attempting to model the part load performance of an air cooled chiller by generating custom performance curves using the E+ HVAC curve fit tool.  We are unsure exactly what performance data to request from the manufacturer to do so.
For the biquadratic CAP_FT and EIR_FT, we plan to request data at various Leaving CHW Temperature (say 44-54°F) and Outdoor Air Dry Bulb Temperatures (~55-105°F).  However, to define the load on the chiller at these points, we need to specify more information.

·        Should CHW flow rate be held constant at 2.4 GPM/ton (AHRI)?

·        Should Entering CHW Temperature be held constant (~54°F)?  I imagine not because there would be no Delta T when you reset leaving CHW Temperature up higher.  So, should the CHW delta T be held constant instead?

For the quadratic EIR_FPLR, at 100% load, the ratings would be at AHRI conditions:  2.4 GPM/ton, 54/44°F Entering/Leaving Chilled Water Temperature, 95°F Outdoor Air Dry Bulb Temperature.  For part load ratios:

·        Should CHW flow rate be varied with a fixed Entering CHW Temperature?  Or vice-versa?

We would appreciate insight from anyone who has run into this before!

Thanks,
Kyle

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