Integrated Part Load Value (IPLV) calculated is not at the AHRI test condition!

asked 2020-12-02 13:54:41 -0500

Mehrdad Vojdani
1125 ●4 ●12 https://www.linkedin.c...

updated 2020-12-03 01:24:00 -0500

I'm using the default openstudio curve setting for chillers in DOE reference buildings simulation to cool an ice storage tank. I have to set chiller output temperature to negative values (e.g. -5). The simulation completed successfully but here is a warning that concerns me:

Chiller:Electric:EIR = Chiller:  Integrated Part Load Value (IPLV) calculated is not at the AHRI test condition.

I'm not familiar with IPLV variable and how important it is... This chiller is not specially selected for ice-making applications and that might be a problem. Since I'm studying a non-standard cooling system, Is this warning important or not?

answered 2020-12-03 03:22:52 -0500

Julien Marrec

29032 ●85 ●74 http://www.effibem.com/

This warning means that the curves (EIRFT and/or CapFT) you use have limits that do not include the AHRI standard conditions, that is a Minimum / Maximum value of x/y on the Curve object that isn't broad enough.

In your specific application, that is worrying, because if you do not include the AHRI standard conditions, you also may not include ice making applications. Since you are doing ice making, your chiller must be water cooled, in which case this warning is issued if either the EIRFT or CapFT curves have limits for Condenser Entering Water Temperatures that do not include one (or both) of these values:

 Real64 const HighEWTemp(30.0);       // Entering water temp in degrees C at full load capacity (85F)
 Real64 const LowEWTemp(19.0);        // Entering water temp in degrees C at minimum reduced capacity (65F)

Extending the limits manually on the curve objects is problematic, because these limits indicate what the curve fitting was done on, and you may find strange or non-physical behavior by extrapolating outside of it. If you are doing ice making, you probably want to be using curves that represent this application anyways.

Source: The CheckCurveLimitsForIPLV routine in StandardRatings.cc

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Thank you @Julien Marrec, that was really helpful. About extending limits and extrapolating (especially leaving temperature) I have no other choice. I couldn't find curves for ice making applications. About the warning, I modified the condenser curve inputs limits and the warning was gone. I hope that's ok!