W. Ryan Geister

1
Beyond the Flanges, A Look at Chilled Water
System Design
W. Ryan Geister CenTraVac Product
Manager Vertical Markets
Trane 3600 Pammel Creek Road LaCrosse WI 54601
7599 TEL [phone] FAX 608 787
2204 rgeister_at_trane.com An American Standard
Company
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Energy Consumption
First Cost
3
Past ...
Annual Energy Cost Conventional Chilled Water
System
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Low Flow Chilled Water Plant Design A Paradigm
Shift - New Rules of Thumb

• New rules of thumb
• 44 ? 41 F chilled water supply
• 16 F ?T across the evaporator
• thats at 1.5 gpm/ton
• 15 F ?T across the condenser
• thats at 2.0 gpm/ton
• Resize the cooling tower accordingly

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Low Flow Chilled Water Plant Design
What are others saying???

• Kelly and Chan (Vanderweil Engineering)
• HPAC January 1999 Optimizing Chilled Water
  Plants
• Chilled water ?T 18 Condenser water ?T
  14.2F
• With the same cost chillers, at worst, the
  annual operating cost with lower flows be about
  equal to standard flows but still at a lower
  first cost
• PGE CoolTools
• Chilled water ?T 12F to 20 F
• Condenser water ?T 12F to 18 F (multi-stage)

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EarthWise Chilled Water Systems

• Good for Business...
• Offers lower first cost and lower operating cost.
• Good for the Environment
• Reduced utility generated greenhouse gas
  emissions.
• Reduces pumping costs...
• A low flow, low temp, high efficiency system
• Leverages todays technology
• Equipment - Chillers, Controls
• System options

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Fundamental Laws
Q m cp ?T

• Mass (capacity) varies directly with flow
• Pressure Drop varies with the square of the flow
• Energy Consumption varies with the cube of the
  flow

• gt ?T Smaller Pipes Tower
• lt ?P Smaller Pumps
• Reduced Operating Costs!

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The Next Step...
Decoupled System
VPF
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How have Chillers Reacted to VPF
Traditionally???
Too Fast a change can be a problem
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But Newer Technology Can Eliminate all Concerns
Stable Chiller Response
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And... By coupling VPF Systems with
SERIES Evaporators, many
advantages emerge...
Bottom line Chillers very capable today!
VPF Saves
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System ExamplesSeries Chillers colder water
savings!
LOAD
LOAD
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How???
CHILLEDWATERRETURN
CHILLEDWATERSUPPLY
41 o F
49 o F
57 o F
105 o F
Run two chillers at 50 or..
56 o F
64 o F
Assuming 85 Entering and 2 GPM/Ton
49 oF
41 oF
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Even better...Part Load Efficiency
CHILLEDWATERRETURN
CHILLEDWATERSUPPLY
OFF
41 o F
57 o F
57 o F
105 o F
.Run your most efficient chiller
64 o F
41 o F
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If applicable...Chilled Water Temperature Re-Set
CHILLEDWATERRETURN
CHILLEDWATERSUPPLY
OFF
44 o F
57 o F
57 o F
105 o F
61 o F
And save more s!
44 o F
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If applicable... AFD Chiller
CHILLEDWATERRETURN
CHILLEDWATERSUPPLY
OFF
41 o F
57 o F
57 o F
And save more s!
IF all three justify the initial capital cost
of the AFD 1. Extensive hours of operation
(24/7, winter cooling) 2. Access to inexpensive
cold condenser water 3. Expensive electricity
(high kWh rates)
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System Flexibility Options...Absorption Chiller
Technology
CHILLEDWATERRETURN
CHILLEDWATERSUPPLY
41 o F
50 o F
57 o F
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System Flexibility Options...Screw Chiller
Technology
CHILLEDWATERRETURN
CHILLEDWATERSUPPLY
41 o F
50 o F
57 o F
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System Flexibility Options...Existing Chiller
Assets
CHILLEDWATERRETURN
CHILLEDWATERSUPPLY
41 o F
50 o F
57 o F
Existing Chiller Assets
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System Flexibility Options...Plant
ExpansionParallel - Primary Secondary (Decoupled)
50 oF
CHILLEDWATERRETURN
CHILLEDWATERSUPPLY
57 oF
41 oF
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System Flexibility Options...Plant Expansion
Parallel/Series - Variable-Primary
CHILLEDWATERSUPPLY
50 oF
CHILLEDWATERRETURN
41 oF
57 oF
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EarthWise Chilled Water Systems

• Exploit technology!
• Low flow
• Low temperature
• High efficiency
• Leverage
• Optimized Controls
• Variable Primary Flow
• Series Evaporators

Operating Cost
First Cost
23
always, always,Always Remember
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W. Ryan Geister CenTraVac Product
Manager Vertical Markets
Trane 3600 Pammel Creek Road LaCrosse WI 54601
7599 TEL [phone] FAX 608 787
2204 rgeister_at_trane.com An American Standard
Company