[Bldg-sim] Variable Speed Screw Chiller Curves

[Robby Oylear]

If you want to take credit for a specific variable speed chiller I would 
recommend working with the manufacturer to get you specific part-load data 
and at varying LIFT DT’s.  Anything simpler would be both inaccurate and 
likely selling yourself short.



Robby Oylear, LEED® AP

Mechanical Engineer

direct: 206.788.4571

cell: 206.354.2721

www. <http://www.rushingco.com/> rushingco.com



From: bldg-sim-bounces at lists.onebuilding.org 
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of David S 
Eldridge
Sent: Wednesday, December 02, 2009 8:40 AM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Variable Speed Screw Chiller Curves



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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