Hi everyone,

I am working on a office building project (e-quest 3.65-7175) in which
baseline case is modelled following ASHRAE-90.1-2010 standard.

Two centrifugal type chillers of 690TR each are assigned to the chilled
water loop with full load COP value entered as 6.16 in chiller input tabs.

As I was analysing the hourly reports for chiller, it was observed that
chiller COP values (based on corrected EIR values in hourly report) are
quite high ranging from 11 to around 25 at part load values in the range of
50% to 0.1%.

This seems very unusual considering that as per chiller manufacturer part
load datapoints the part load COP values starts decreasing below 35-30%
part load; whereas using e-quest default chiller curves, the chiller COP
value seems to go on increasing even at lower part load values.

Has anyone observed this before, or am I going wrong somewhere?

Also due to above issue, when part load data points provided by chiller
manufacturer are entered in proposed model and default e-quest performance
curves are used in baseline model, expected energy savings under space
cooling consumption are not achieved during comparison.

I have attached screen-shots showing e-quest default curve coefficients
(EIR-FT, EIR,-fPLR & Cap-FT curves) for centrifugal chiller and a sample
manufacturer's part load details for reference.

Do I need to change the default curve coefficients from e-quest to get more
accurate results? If so, please kindly let me know the changes to be made
or the process for finding correct part load curve coefficients for chiller.

Thanks in advance.