[Bldg-sim] Cooling tower to chilled water (bypass chiller) free-cooling in eQuest?
Edelstein, David
Dedelstein at AKF-ENG.com
Wed Jun 11 08:47:01 PDT 2008
I am trying to model cooling tower water to chilled water free-cooling
(bypass the chiller) in eQuest. If anyone has experience modeling this
in eQuest it would be appreciated.
Thanks in advance.
David Edelstein, P.E.
<http://www.akfgroup.com/>
1501 Broadway, Suite 700
New York, NY 10036
dedelstein at akf-eng.com
D: 646-720-9863
P: 212-354-5656
F: 212-354-5668
www.AKFGroup.com <http://www.AKFGroup.com>
Arlington * Boston * New York * Philadelphia * Princeton * Stamford *
Mexico City
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________________________________
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Bill
Sent: Thursday, March 27, 2008 3:35 AM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] FW: Ice storage chilling system - getting
LEEDpoints?
One thing to be careful of when considering the impact of low
temperature air distribution on energy use: Depending on climate, many
hours of economizer cooling may be lost. This can be a huge impact in
mild climates, and should be evaluated in all climates that have
moderate temperatures for at least a few months a year. The increased
plant energy use from the loss of "free" cooling can dwarf the air
transport savings, unless this is accounted for in the design and
control of the air systems.
--Bill
William E. Koran, P.E.
Senior Engineer
Q u E S T
Quantum Energy Services and Technologies
Voice: 503-557-7828
Fax: 510-540-7268
Web: www.quest-world.com <http://www.quest-world.com/>
________________________________
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Keith
Swartz
Sent: Wednesday, March 26, 2008 7:04 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] FW: Ice storage chilling system - getting LEED
points?
Bill makes a good point about taking advantage of the lower temperature
of the ice system. I worked on a project that had an ice storage system
that took advantage of the colder temperature. We made the chilled water
supply temperature 38F and return temperature 62F (DeltaT=24F). The
pumping power saved was pretty significant, since the chilled water had
to be pumped underground more than 1200 feet from the Chiller Plant to
the main building. The lower chilled water temperature allowed me to use
lower supply air temperature at the air handlers, which allowed me to
select smaller air handlers (due to lower cfm), which allowed me to
actually fit the air handlers into the allotted space! So there are more
benefits than just energy cost benefits...if you take advantage of the
opportunities.
Sincerely,
Keith Swartz, PE, LEED(r) AP
Energy Center of Wisconsin
455 Science Drive
Suite 200
Madison, WI 53711
Phone: 608-238-8276 ext. 123
Fax: 608-238-0523
www.ecw.org <http://www.ecw.org/>
The Energy Center of Wisconsin is an independent, nonprofit organization
that seeks solutions to energy challenges.
________________________________
From: William Bahnfleth [mailto:wbahnfleth at psu.edu]
Sent: Sunday, March 23, 2008 1:36 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Ice storage chilling system - getting LEED
points?
I doubt that night-time wet bulb depression is sufficient in most places
to compensate for the difference between saturated evaporating
temperatures associated with typical chilled water and ice production
systems. However, break-even seems to be attainable for air-cooled
systems.
Variable speed compressors and thermal storage are a good match because
VS operation maximized the impact of a lift reduction.
A key to saving energy with ice storage or any other low temperature
production scheme is to take advantage of the low temperature source.
The most common examples are low temperature water distribution and low
temperature air distribution to achieve larger temperature differences
and reduce transport energy consumption.
Other benefits of thermal storage that are significant, but frequently
poorly quantified, if quantified at all, are load management
effects--more efficient part loading, preferential loading of more
efficient equipment, etc.
Bill Bahnfleth
At 01:41 PM 3/23/2008, Wyman, Kevin L UTPWR wrote:
Content-class: urn:content-classes:message
Content-Type: multipart/alternative;
boundary="----_=_NextPart_001_01C88D0D.0FE7F528"
Agree with everything David pointed out. While ice making chillers would
use more energy to create the colder temperatures needed for phase
change, they often do this at night when cooling tower doesn't work as
hard and ambients drop (in some climates) so net energy is often less.
In other words, the kWh consumption can be less as well as peak kW
savings under rate tarriff considerations.
Kevin L. Wyman, P.E.
LEED AP
On-Site Power Product Management
UTC Power
195 Governor's Highway
South Windsor, CT 06074
(860) 727-7020 (V)
(860) 660-0723 (F)
(860) 882-9595 (M)
Kevin.wyman at utcpower.com
----- Original Message -----
From: bldg-sim-bounces at lists.onebuilding.org
<bldg-sim-bounces at lists.onebuilding.org>
To: bldg-sim at lists.onebuilding.org <bldg-sim at lists.onebuilding.org>
Sent: Sun Mar 23 09:32:47 2008
Subject: Re: [Bldg-sim] Ice storage chilling system - getting LEED
points?
For EAC1, the comparison is about energy cost. The ice storage will
save money IF you have time-of-day electricity rates in place. If you
are using the EIA state average rate data, it won't show a savings.
Ice storage actually uses more energy not less -- you can get more out
of the ice, but remember that you have to spend the same amount of
refrigeration energy to make the ice, plus the chiller will be working
against unfavorable temperatures and fluid properties which will use
more compressor energy compared to conventional chilled water, per
ton-hr.
Maybe there is merit if you can say what savings there are from
night-time electricity compared to day-time electricity, or if there is
some major problem with electricity distribution in your area.
Your client may be interested in first cost savings if you design a
partial storage system, but don't expect any LEED credit for that.
David
________________________________
From: bldg-sim-bounces at lists.onebuilding.org on behalf of Sasa Pantic
Sent: Sat 3/22/2008 2:21 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Ice storage chilling system - getting LEED points?
Dear colleagues,
I would kindly ask for an information please.
I am thinking of designing an ice storage chilling system that would
generate ice at night, during low electricity rates, and will be used
during the following day for to reduce peak cooling demands of the
building.
Could I get LEED credits in Energy and Atmosphere section for reducing
the cooling cost?
In addition, taking into account that ice can absorb more heat than that
of water and therefore will lead to much more chilling capaciity or
"tons" of refrigeration from the same size/horsepower rating of
compressors than a conventional type of chiller.
I gues I could get more LEED credits for being environmentally friendly?
Please advise.
Thanks muchly.
Regards Sasa Pantic
________________________________
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_________________________________________________
William P. Bahnfleth, PhD, PE, FASHRAE
Professor of Architectural Engineering
Director, Indoor Environment Center
The Pennsylvania State University
104 Engineering Unit A
University Park, PA 16802 USA
voice: 814.863.2076 / fax: 814.863.4789
e-mail: wbahnfleth at psu.edu
http://www.engr.psu.edu/ae/faculty/bahnfleth/
http://www.engr.psu.edu/ae/iec/
_________________________________________________
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