Use Existing Chilled Water
Asset By Interconnecting a
Customer’s Chiller System
to a District Cooling
System
June 18, 2007
Applied
Engineering
Services
An engineering solutions company.
Introduction
-North Building Built in 1961
• Converted to DC in 1991
-South Building Built in 1991
• Fully occupied in 1994
• Approximately 1 million square feet
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West Street View
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Washington Street View
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View of Capital From
Government Place
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IGC – South Chilled Water
• Two (2) 800-ton chillers using R-11
• Total connected AHU load 3,200 tons
(peak of 2400 tons anticipated)
-Chiller in lower level
-Towers mounted on the roof
• 1 million gallon chilled water storage
tank installed
-Chilled water storage tank also used
for a backup for data center cooling
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IGCS-Problems Encountered
• Concrete chilled water storage tank
needed an open system (tank at lowest
point)
• VE item in original design reduced
pipe schedule from STD to SCH 10
• Chemical treatment contract was
removed from MC’s bid
• Only one chiller dedicated to chilled
water tank charging at night due to
labor dispute
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IGCS-Problems Continued
• Open system/thin wall pipe/no
chemical treatment – pipe leaks abound
• Control system breakdowns caused
water hammer and vacuum conditions
• Tower capacity reduction due to scaled
fill – an acid cleaning was performed
• Several 90°F plus days in a row caused
the chilled water storage tank to
deplete
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IGCS Solutions Implemented
• Open chilled water system removed
from building
• Data center mechanical backup cooling
installed
• District system added to the building as
the “main” cooling system. Building
Chillers used as a means to “load shed”
during peak cooling periods
• Install new cooling towers to match
chiller load
• Update mechanical room code
requirements
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IGCS Project 1
Install data center backup chiller capacity
• Three 120 ton condenser less chillers
installed in the generator room
• A/C condensers mounted on the roof
• Commissioned and checked with
generator operation
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Condenserless Chiller
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IGCS Project 2
Chilled water interconnect with district chilled water system
• New piping system installed (SCH 40)
• New VSD chilled water circulating
pumps installed
• Connection to district system completed
• New tower and water treatment system
installed
• Control system changes to initiate a
“load shed” scenario
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Interior Piping
• Interior piping replaced
• 1 ½ years total construction
period
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Mechanical Room Piping
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New Ref Storage Tank
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New Towers
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Key to “Load Shed” Design
• Building Balance Valve
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Temp Control and Building
Balance Valve Location
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Lessons Learned:
Commissioning
• Remote condensers and
refrigerant migration
• Tuning a control valve
• Time effort in commissioning key
chiller plant
• Tower water level control
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Current Operations
• 2005 summer data
• 2,858 peak demand
• Approximately 1000 tons load
shed by site chillers
• 112,900 THR used in July/August
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Recent Issues Developed
2006 summer operating problems developed
• Control system becomes unstable
• Chiller Plant has shutdown when
left unattended
• 1990 vintage control system (parts
an issue)
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Conclusion
• Indiana State Government gets a
break on DC pricing by allowing
use of existing equipment
• CTE (district cooling company)
connects another customer. No
generating capacity need be added
• 0.9 KW/ton chillers replaced with
0.6 KW/ton or better cooling
capacity
• Control system bugs need to be
worked out
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Closing
• Questions? Comments?
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7999 Knue Road
Suite 300
Indianapolis, Indiana 46250
Phone: 317.585.8920
Fax: 317.585.8921
www.applied-e-s.com
Thank
You
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