[Bldg-sim] Variable Speed Screw Chiller Curves

David S Eldridge DSE at grummanbutkus.com
Wed Dec 2 08:39:44 PST 2009


You may want to run an eQuest report on the chiller to see how the efficiency is varying throughout the year.  Output the load and the power at each hour and you should get a better idea of whether the curves are working or not, or if the default curves are reasonable for your specific equipment.

David
http://www.grummanbutkus.com



From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Dan Russell
Sent: Wednesday, December 02, 2009 10:35 AM
To: Dan Nall; Kingsley,Michael L.; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Variable Speed Screw Chiller Curves

Well, I’m going over a year back into the archives, but hopefully someone can help.  I’m modeling a project with 500 Ton Carrier Evergreen Water-Cooled Screw Chillers and would like to take advantage of the part-load efficiency benefits.  It appears that Dan Nall posted custom efficiency curves for this specific equipment a while back, but when I use them in eQUEST my cooling energy gets tripled (from 800 MWh to 2450 MWh) as compared to the default eQUEST curves for Water-cooled Screw chillers.  Does anyone have experience using these curves effectively?  Am I misinterpreting the curve data?  Are they intended for something other than eQUEST inputs?  Or are the default eQUEST curves unrealistically efficient?

Thanks for any input,

Dan Russell
Engineering Incorporated

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Dan Nall
Sent: Tuesday, August 26, 2008 1:17 PM
To: Kingsley,Michael L.; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Variable Speed Screw Chiller Curves


Try these on for size;

"VFDSCrew EIR fPLR" = CURVE-FIT

TYPE = CUBIC

INPUT-TYPE = DATA

INDEPENDENT = ( 1, 0.75, 0.5, 0.25 )

DEPENDENT = ( 1, 0.97307, 1.01436, 1.3616 )

..

"Carrier-EIR-fCHWT&CWT" = CURVE-FIT

TYPE = BI-QUADRATIC-T

INPUT-TYPE = COEFFICIENTS

COEFFICIENTS = ( 0.767051, -0.0236208, 0.0004375, 0.0024939, 0.0002337,

-0.000418 )

..

"Carrier-EIR-fPLR&dT" = CURVE-FIT

TYPE = BI-QUADRATIC-RATIO&DT

INPUT-TYPE = COEFFICIENTS

COEFFICIENTS = ( -0.0230025, 0.902964, 0.0935993, 0.00347819,

-2.45759e-005, -0.00196462 )

..

"Carrier-CAP-fCHWT&CWT" = CURVE-FIT

TYPE = BI-QUADRATIC-T

INPUT-TYPE = COEFFICIENTS

COEFFICIENTS = ( 0.448509, 0.0185587, -0.00028125, 0.00306901,

-5.0201e-005, 0.000108475 )




-----Original Message-----
From: "Kingsley, Michael L."
Sent: Aug 26, 2008 2:15 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Variable Speed Screw Chiller Curves

Does anyone have DOE-2 performance curves for a variable speed screw chiller (I believe the Carrier Evergreen 23XRV is the only one now) that they would be willing to share?

Thanks in advance.

Michael Kingsley

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