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© American Standard Inc. 2006© American Standard Inc. 2006
Chiller–Tower Optimization …
Do It Right!
Chiller–Tower Optimization …
Do It Right!
The Trane CompanyLa Crosse, Wisconsin
© American Standard Inc. 2006© American Standard Inc. 2006
chiller–tower optimizationThe Question …
“알맞은”냉각수온도는몇도인가?
© American Standard Inc. 2006© American Standard Inc. 2006
Simple Case(Constant Water Flow)
LoadCW TempChiller Design
Wet BulbLoadCW TempTower Design
© American Standard Inc. 2006© American Standard Inc. 2006
Link Is Condenser Water Temperature
CondenserWater Temp Chiller kW Tower kW Total kW
??
© American Standard Inc. 2006© American Standard Inc. 2006
Or Said Another Way …
0
50
100
150
200
250
300
350
72 73 74 75 76 77 78 79 80 81 82 83 84 85
Chiller kWTower kWTotal kW
Condenser Water Temperature
kW
( 29.5 C)( 22.5 C)
© American Standard Inc. 2006© American Standard Inc. 2006
chiller–tower optimizationCondenser Water Control
Hot? (85°F [30°C])
Cold? (55°F [13°C])
Wet Bulb + 5°F [3°C]?
Optimized?
© American Standard Inc. 2006© American Standard Inc. 2006
a simple case …Component Models
ChillerChiller design
ARI-certified selections
Polynomials (다항식)f(Design kW, % Load)f(CW temperature)
ConstantsCondenser water flowChilled water temperature
Cooling TowerTower design
CTI-certified selections
FunctionsWet bulbHeat rejectedTower airflow
ConstantCondenser water flow
© American Standard Inc. 2006© American Standard Inc. 2006
Where’s The Meter?
A. On the building.
B. On the chiller.
© American Standard Inc. 2006© American Standard Inc. 2006
What’s The Bottom Line?
400-ton [1400 kW] chiller
0.58 kW/ton [6.06 COP]
85°-95°F [29.4°-35°C] condenser water temperature differential
78°F [25.6°C] designwet-bulb temperature
“ARI unloading” …Full load 17% of the time75% load 39% of the time50% load 33% of the time25% load 11% of the time
Economics …$0.08 per kWh$12.00 per kW1,300 equivalent full-load hours
© American Standard Inc. 2006© American Standard Inc. 2006
The Bottom Line … $
Minimumtempera ture
Design CW WB + 5degrees
Optimized$47,500.00
$48,000.00
$48,500.00
$49,000.00
$49,500.00
$50,000.00
$50,500.00
$51,000.00
Minimumtempera ture
Design CW WB + 5degrees
Optimized
Chiller+Tower Yearly Estimated Operating Cost OK
© American Standard Inc. 2006© American Standard Inc. 2006
The Bottom Line … 71°F WB
Minimumtempera ture
Design CW WB + 5degrees
Optimized$42,500.00
$43,000.00
$43,500.00
$44,000.00
$44,500.00
$45,000.00
$45,500.00
$46,000.00
$46,500.00
$47,000.00
Minimumtempera ture
Design CW WB + 5degrees
Optimized
Chiller+Tower Yearly Estimated Operating Cost OK
© American Standard Inc. 2006© American Standard Inc. 2006
Minimumtempera ture
Des ign CW WB + 5degrees
Optimized$39,500.00
$40,000.00
$40,500.00
$41,000.00
$41,500.00
$42,000.00
$42,500.00
$43,000.00
$43,500.00
$44,000.00
$44,500.00
Minimumtempera ture
Des ign CW WB + 5degrees
Optimized
Chiller+Tower Yearly Estimated Operating Cost OK
The Bottom Line … 65°F WB
© American Standard Inc. 2006© American Standard Inc. 2006
where’s the meter?The Only Possible Response …
On the building!On the building!
© American Standard Inc. 2006© American Standard Inc. 2006
chiller–tower optimizationThe REAL Bottom Line …
Our customers shouldn’t have to pay more!
© American Standard Inc. 2006© American Standard Inc. 2006
Plant Power vs CWS
0.0
200.0
400.0
600.0
800.0
1,000.0
1,200.0
60 62 64 66 68 70 72 74 76 78 80 82 84 86 88
Condenser Water Setpoint ( )캟
Pow
er (k
W)
Lowest condenser water temperature available from tower at this load and wet-bulb temperature
Chillers cannot meet load above this condenser water temperature
Optimal operation
1,550 tons, 65 Wet-bulb 캟
T t
1,160 tons, 59 Wet-bulb 캟
T
730 tons, 54 Wet-bulb Temperature캟
Braun, Diderrich
Hydeman, Gillespie, Kammerud
Schwedler,ASHRAE Journal
Hydeman, et. al. Pacific Gas and Electric. Used with permission.
chiller–tower optimizationIs It Real?
© American Standard Inc. 2006© American Standard Inc. 2006
chiller–tower optimizationHow Do You Do It?
With real-life controls!
© American Standard Inc. 2006© American Standard Inc. 2006
chiller–tower optimizationHow Do You Calculate Savings?
System Analyzer™
© American Standard Inc. 2006© American Standard Inc. 2006
chiller–tower optimizationHow Do You Calculate Savings?
TRACE® 700
© American Standard Inc. 2006© American Standard Inc. 2006
chiller–tower optimizationWhat Else Should You Know?
신규또는개보수시설모두적용가능
About 30 installations
최적의 set point는
냉동기 type에따라변한다
Two-speed 또는variable-speed cooling tower fan이좋은방법이다.
© American Standard Inc. 2006© American Standard Inc. 2006
chiller–tower optimizationIn Summary …
냉각수온도가저온일수록더이로운것은아니다.
중요한것은최적운전제어이며이를통해비용절감효과를거둘수있다.
비용절감은사실이고측정되어질수있다.
다양한제어방식이가능하다!