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Do It Now - Optimize Your Chiller Plant - The
Choice is Yours
Review the following alternatives and then ask "Is your chiller plant optimized for total energy savings"?
Proven control strategies significantly improve the efficiency of a chiller
plant. These can be defined as Cooling Tower Temperature
Relief, Condenser Water Temperature Reset,
Variable Condenser Water Flow Rate, and
Chilled Water Temperature Reset.
The difficulty has always been that the application of these strategies to chiller plant
operation is problematic and expensive, until recently. Most applications when
instituted in the past caused excessive chiller starts, or chiller surging or
both. These problems are typically resolved by eliminating the savings
that were promulgated through the original design.
New, recently patented application methods are now available which eliminate
the problems of chiller surging and excessive starts and result in long term
savings.
The choices discussed below use some or all of the strategies defined above. Note that
all are recent and patented or patent pending. The
Chiller Plant Optimizer TM is
an independent solution, that does not require special knowledge from
manufacturers and can be readily retrofitted to existing plants, plus it is low
cost.
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The Chiller Plant Optimizer
is provided as a stand-alone distributed control unit that can interface with
the typical building automation system. It uses a patented method
with a unique application system. The control strategies are
prepackaged in the controller using open source software logic. The primary
strategies offered are: Condenser Water Temperature Reset,
Cooling Tower Temperature Relief and Variable
Condenser Water Flow Rate.
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Trane Company has a set of optimizing strategies
available as part of a plant control package. These strategies depend on
propriety performance characteristics of Trane Chillers. Therefore they
describe techniques as proprietary or “secret” and include very limited details on their
web site. One only needs to study their patent patent to know that
these strategies can also be defined as : Cooling Tower
Temperature Relief and Condenser Water
Temperature Reset. They prefer constant speed condenser pumps. Reference U.S. Patent 5,600,960 dated
February11, 1997 assigned to American Standard, Inc (Parent of Trane).
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Johnson Controls patented a “near optimal” solution that
controls cooling tower fans in response chiller load monitoring, and is
directly referenced in Trane’s patent. This strategy is a less precise form of
Cooling Tower Temperature Relief. Reference
U.S. Patent No. 5,040,377 dated August 20, 1991
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Thomas Hartman Company, through a sister company,
licenses a design for chiller plants that is based on recent U.S. Patent No.
6,257,007 dated July10, 2001. It also incorporates
all of the strategies identified above. This technology is also based on exact performance
characteristics and therefore requires data from the manufacturers that may be
proprietary.
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