Reported IPLV in IP units is inconsistent with IPLV.IP

lymereJ commented 3 years ago

Issue overview

Currently EnergyPlus calculates a chiller's IPLV using rating part load conditions from AHRI Standard 551/591 which uses SI units and converts it to IP units for reporting. However, the IP version of the standards (550/590) uses slightly different temperatures than the SI version.

Screenshot from the SI version of the Standard (551/591) Screenshot from the IP version of the Standard (550/590)

85 deg. F is ~29.44 deg. C, not 30 deg. C
75 deg. F is ~23.89 deg. C, not 24.5 deg. C
65 deg. F is ~18.33 deg. C, not 19 deg. C

For that reason, building energy code use the IPLV.SI and IPLV.IP terminology, where IPLV.IP isn't a conversion of IPLV.SI to IP units but an IPLV calculated using rating part load conditions from AHRI Standard 550/590. It might be best to report both IPLV.SI and IPLV.IP instead of "IPLV in SI Units" and "IPLV in IP Units".

Details

Some additional details for this issue (if relevant):

Version of EnergyPlus: 9.5

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

[ ] Ticket added to Pivotal for defect (development team task)
[ ] Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)

lymereJ commented 3 years ago

AHRI Standards 551/591 uses a leaving water temperature of 7.0 deg. C (see picture above). But the current method uses 6.67 deg. C, see https://github.com/NREL/EnergyPlus/blob/ed3a9d36c86aad48000128ae7975805818f1e207/src/EnergyPlus/StandardRatings.cc#L272

JasonGlazer commented 2 years ago

This is related to #7038.

@lymereJ I would probably classify this as a new feature request unless you are saying that it was not working properly with the old version of AHRI 550/590

lymereJ commented 2 years ago

@JasonGlazer - I think this has always been an issue. AFAIK, there are always been differences in rating conditions between AHRI Standard 550/590 (IPLV.IP) and 551/591 (IPLV.SI).

Nigusse commented 1 year ago

This issue will be addressed as part of issue #9829 and PR #9830.

NREL / EnergyPlus