[Equest-users] Chiller ROI - HELP!

[Brett Sanicola]

Thank you all.  I see that the below 20% load, where I was predominantly
operating, the KW/Ton shoots up drastically.  Thanks, that explains my
results.

 

Respectfully,

 

Brett Sanicola

Engineer

ASB Engineering

(516) 785-4200

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Jim
Marsh
Sent: Thursday, April 01, 2010 4:25 PM
To: 'Pasha Korber-Gonzalez'; 'James Hansen'
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Chiller ROI - HELP!

 

Brett, attached are some example kw/ton curves for existing chillers on
a recent project.  Chiller #1 is a 250 ton unit, and chillers 2 thru 4
are 550 ton units.  Chillers 1 and 2 are ~ 15 years old, and chillers 3
and 4 are newer with better efficiencies.  All 4 chillers are water
cooled.  The curves show efficiencies with and without Adjustable
Frequency Drives.  It's hard to tell the difference between the "w/AFD"
and "w/o AFD" curves, but the "w/AFD" curves have a lower kw/ton except
at full load.

 

Jim Marsh, PE, LEED AP

SEG, Inc.

2550 Walsh Avenue

Suite 120

Santa Clara, CA 95051

Desk: 408 260 8008 Ext 210

Cell: 408 656 3096

Fax: 408 260 8018

http://seg-corp.com/ <http://seg-corp.com/> 

 

 

This communication constitutes an electronic communication within the
meaning of the Electronic Communications Privacy Act, 18 USC 2510, and
its disclosure is strictly limited to the recipient intended by the
sender of this message.  This communication may contain confidential and
privileged material for the sole use of the intended recipient and
receipt by anyone other than the intended recipient does not constitute
a loss of the confidential or privileged nature of the communication.
Any review or distribution by others is strictly prohibited.  If you are
not the intended recipient please contact the sender by return
electronic mail and delete all copies of this communication. 

Please consider the environment before printing this email

 

 

 

________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Pasha
Korber-Gonzalez
Sent: Thursday, April 01, 2010 1:11 PM
To: James Hansen
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Chiller ROI - HELP!

Brett,

 

to get better part load data and efficiency of your proposed chiller
replacement, call your chill sales engineer and ask them to generate a
part load performance report for you in 10% unloading increments, then
you can see the decrease in performance efficiency for each part-load
step of the chiller.  Also be sure that you recognize if you are looking
at RATED Conditions (which means chiller performance at ARI standard
conditions), or at DESIGN conditions (which are your project's specified
operating conditions--this would account for part load efficiencies if
you were running a 12-or 14 Degree delta-T across your chiller.)

 

Before you set up a new performance curve you will need to get this data
supplied from the manufacturer.

 

Pasha

On Thu, Apr 1, 2010 at 2:01 PM, James Hansen <JHANSEN at ghtltd.com> wrote:

KW/ton drops off with decreasing part load, and since the chiller isn't
always operating at ARI full load conditions, you can't just divide
total chiller energy consumption (in KWH) by the total cooling load (in
btu) and hope to get anywhere near the full load rated KW/ton.

 

As you go about this ROI study, make sure that when you are analyzing
your proposed chiller replacement, that you create a custom EIR vs PLR
curve based on manufacturer's data, otherwise you're using a default
DOE-2 curve that isn't necessarily correct.

 

Furthermore, to make the study worthwhile, the existing chiller model
really needs to be normalized as best as possible to actual building
operating conditions.  You can get away without doing it for a simple
comparison, but it would be more accurate if you normalized to utility
bills.

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

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

 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Brett
Sanicola
Sent: Thursday, April 01, 2010 2:38 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Chiller ROI - HELP!

 

I've been attempting to calculate a simple ROI for a new 250 ton chiller
our client wants to install to replace his older chiller.  I ran the
simulation for the default "high rise hotel" construction which, to my
luck, is quite similar to the actual building.  The detailed results,
however, are not making sense to me.  Specifically, when I look at
Equipment Loads and Energy Use for the Chiller, the Elec Use and Cool
Load don't coincide given the default Chiller efficiency of .67kw/ton.
For example they give a Chiller Elec Use of 535453 KWH and a Cool Load
of 3294 MBTU.  However, according to my calculations, at .67KW/TON,
535453 KWH should give me closer to 9590 MBTU.  I see most of the hours
are in part load range, but does the efficiency drop off that
dramatically at part load that it would explain the discrepancy?  Which
numbers should I base my analysis on, the Cool Load number or the Elec
Use number.

 

Also, on the same page (Equipment Loads and Energy Usage), it gives me a
peak load of 2436 KBTU/HR.  However, when I go to the section titled
"Building Peak Load Components" the peak cooling load is significantly
less (1619 KBTU/HR)

 

At this point, I have no idea what any number represents, since I don't
know how it was calculated.

 

I greatly appreciate any help!  Thanks.

 

Respectfully,

 

Brett Sanicola

Engineer

ASB Engineering

(516) 785-4200

________________________________

The information contained in this communication is confidential, may be
privileged, and is intended only for the use of the addressee.  It is
the property of GHT Limited.  Unauthorized use, disclosure or copying of
this communication or any part thereof is strictly prohibited and may be
unlawful.  If you have received this communication in error, please
notify me immediately by return e-mail or by e-mail to ght at ghtltd.com
<mailto:ght at ghtltd.com> , and destroy this communication and all copies
thereof, including all attachments.  Thank you. 


_______________________________________________
Equest-users mailing list
http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
To unsubscribe from this mailing list send  a blank message to
EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20100401/f3348ebb/attachment.htm>