[Bldg-sim] chiller performance curves?

[Xiaobing Liu]

Not really. Some curves are the function of temperature and/or other variables with dimension. Although the results of the performance curves are usually dimensionless, the coefficients of the curves depends on the unit of the variables.

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org]On Behalf Of Dan Russell
Sent: Monday, December 08, 2008 3:42 PM
To: Chien Si Harriman; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] chiller performance curves?



It is my understanding that the chiller curve data are dimensionless ratios, so the curve-fits should work regardless of units-system.  The raw data would be different, but the curve coefficients should be identical.



Can someone confirm this?



Thanks,



 Dan Russell, EIT



cid:image001.jpg at 01C840A4.E711B250



From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Chien Si Harriman
Sent: Monday, December 08, 2008 1:08 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] chiller performance curves?



Hi all-



Sort of technical question here that requires some knowledge of the inner workings of either EnergyPlus or DOE2/eQuest...hoping there is someone out there who knows the answers to this.  What does either an EnergyPlus or DOE2 user have to do when dealing with different units, particularly when it comes to the curve fits?  Obviously, the same coefficients do not apply for both units.  Do the default curve coefficients for the chiller, for example, have both IP and metric equivalents?



Does anyone know how this works?  Has anyone bumped into a regression model that can take raw data in metric units, and create a set of coefficients in one set of units (let's say IP for starters), and then use those newly-created coefficients, generate an new set of raw data, and then create a new regression to produce a new set of coefficients in converted units (Metric, in this case?)



Has either DOE2 or EnergyPlus already solved this problem, and I don't need to even think about itanymore?



Thanks,











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