Chilled Water Loop Optimization€¦ · Broida; Cooling Tower Approach Set Point WB 55 F WB 70 F...
Transcript of Chilled Water Loop Optimization€¦ · Broida; Cooling Tower Approach Set Point WB 55 F WB 70 F...
Chilled Water Loop
Optimization
• Kazimir Gasljevic
• Richard Dewey
• Sandro Sanchez
WHAT WE STARTED WITH:
LOOP OUTLINE:
WHAT WE STARTED WITH:
LOOP OUTLINE:
- Justification for the loop
WHAT WE STARTED WITH:
LOOP OUTLINE:
- Justification for the loop
Value of the loop piping, $10 Million Vs. Value of the
chillers on the loop, $5 Million
WHAT WE STARTED WITH:
LOOP OUTLINE:
- The game changed after the introduction of
variable speed chillers
WHAT WE STARTED WITH:
LOOP OUTLINE:
- The game changed after the introduction of
variable speed chillers
•There will probably be no further expansion of the
loop.
WHAT WE STARTED WITH:
LOOP OUTLINE:
- The game changed after the introduction of
variable speed chillers
•There will probably be no further expansion of the
loop.
•Modular variable speed chillers are the better way to go
in our climate.
WHAT WE STARTED WITH:
ORIGINAL CONTROLS CONCEPT:
WHAT WE STARTED WITH:
ORIGINAL CONTROLS CONCEPT:
• Focused mostly on functionality with not much concern
given to efficiency issues.
WHAT WE STARTED WITH:
OVERALL LOOP ENERGY EFFICIENCY:
WHAT WE STARTED WITH:
OVERALL LOOP ENERGY EFFICIENCY:
• 0.85 kW/ton, 0.8 kW/ton after installation of the variable
speed chiller.
SCOPE OF THE MBCx
PROJECT:
SCOPE OF THE MBCx
PROJECT:
An MBCx project focused on improving existing
hardware with better usage and controls (no
capital costs).
SCOPE OF THE MBCx
PROJECT:
FUNCTIONALITY:
SCOPE OF THE MBCx
PROJECT:
FUNCTIONALITY:
• To automatically maintain a constant Differential
Pressure, as well as staging the chillers off and on
smoothly.
SCOPE OF THE MBCx
PROJECT:
ENERGY EFFICIENCY:
SCOPE OF THE MBCx
PROJECT:
ENERGY EFFICIENCY:
• Improve the efficiency of all chiller plants.
SCOPE OF THE MBCx
PROJECT:
EXTRAS:
SCOPE OF THE MBCx
PROJECT:
EXTRAS:
• Critical cooling
• Use loop thermal capacity for load shedding
• Leak detection and leak location.
STRATEGY:
STRATEGY:
Hiring Consultants
vs.
Doing the work in House:
STRATEGY:
Hiring Consultants
vs.
Doing the work in House:
• "Fits all" algorithm vs. "algorithm for a given situation“
• Intimate Knowledge of the plant
STRATEGY:
OTIMIZATION METHODOLOGY:
STRATEGY:
OTIMIZATION METHODOLOGY:
• Sacrifice slightly on the ideal mathematical optimum for
a robust sustainable system.
• Take in to account temporal changes in the performance
of the system components.
OPTIMIZATION
ALGORITHM :
OPTIMIZATION
ALGORITHM :
Optimization of the Loop
OPTIMIZATION
ALGORITHM :
• Decide which chillers to run based on the capacity and
efficiency of individual chillers.
Optimization of the Loop
OPTIMIZATION
ALGORITHM :
• Decide which chillers to run based on the capacity and
efficiency of individual chillers.
• Decide the Condenser Water temperature set point.
Optimization of the Loop
OPTIMIZATION
ALGORITHM :
• Decide which chillers to run based on the capacity and
efficiency of individual chillers.
• Decide the Condenser Water temperature set point.
• Decide the Differential Pressure set point (constant for
now).
Optimization of the Loop
OPTIMIZATION
ALGORITHM :
• Decide which chillers to run based on the capacity and
efficiency of individual chillers.
• Decide the Condenser Water temperature set point.
• Decide the Differential Pressure set point (constant for
now).
• Consider a needed cooling capacity of the loop in the
immediate future (few hours), based on the time of day
and the weather forecast.
Optimization of the Loop
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0.6
0.8
1
1.2
0 200 400 600 800 1000 1200
Eff
icie
ncy
[k
W/t
on
]
Load [tons]
Chiller Efficiencies at 74 F Condenser Temp and 42 F Supply Temp
ESB
CNSI
Bren
Library
Chemistry, Broida
ENG 1
BIO 2
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0.4
0.6
0.8
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1.2
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1.6
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Eff
icie
ncy
[k
W/t
on
]
Load [tons}
Plant efficiencies at WB 60 F
ESB
CNSI
Bren
Library
Chemistry
ENG 1
BIO 2
Broida
OPTIMIZATION
ALGORITHM :
Optimization of individual chillers
OPTIMIZATION
ALGORITHM :
● Balancing power for compressor, cooling tower fan,
condenser pump. Use performance curves updated for the
momentary changes (maintenance issues etc.)
Optimization of individual chillers
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20
30
40
50
60
70
80
90
100
0 20 40 60 80 100 120 140
Tem
per
atu
re [
F]
Time [Minutes]
ESB Chiller Temperatures
Condenser Refrigerant
Condenser Water Supply
Air Wet Bulb
Condenser Water Return
Evaporator Water
Return
Evaporator Water
Supply
Evaporator Refrigerant
Condenser
Evaporator
Condenser Pump
Cooling Tower
Del
iver
ed
Ch
ille
r L
oa
din
g
0
1
2
3
4
5
6
7
0 100 200 300 400 500 600 700 800 900
Ap
pro
ach
= T
sat
-T c
hw
[F
]
Tons
ESB Condenser Problem, 8/26/2014
Before Cleaning
Ideal
After First Cleaning
After Second Cleaning
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5
10
15
20
25
30
35
0 5 10 15 20 25 30 35 40 45
Ap
pro
ach
Tem
p [
F]
Fan power (both) [HP]
Broida Cooling Tower Performance (BAC model)
100% speed 90% speed 80% speed 60% speed
55 F WB, 100% load
55 F WB, 50% Load
70 F WB, 100% Load
70 F WB, 50% Load
100% Load = 8.2 kW/F
50% Load = 4.2 kW / F
55 WB, 75% Load
70F WB, 75% Load
1.2 F
1.8 F
2.5 F
2.4 F
3.6 F
4.8 F
3.33 F
5 F
6.66 F
4.3 F
6.45 F
8.6 F
1.8 F
2.7 F
3.6 F
0.6 F
0.9 F
1.2 F
3 F
4.5 F
6 F
100%
75%
50%
How many F App T can be increased at any fan power saving before compressor power increase becomes larger than fan power reduction.
1 HP = 0.84 kW (0.9 motor efficiency)
70% speed
50, 19
75, 18
100, 17
50, 14.5
75, 13.75
100, 13
y = -0.04x + 21
y = -0.03x + 16
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13
14
15
16
17
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19
20
0 20 40 60 80 100 120
Ap
pro
ach
Tem
[F
]
Chiller Load %
Broida; Cooling Tower Approach Set Point
WB 55 F
WB 70 F
Linear (WB 55 F)
Linear (WB 70 F)
For a given % load: AT = (AT55WB - AT70WB) * (70 - WB) / 15
Add few F for a degraded cooling tower performance (determine experimentally)
MEASUREMENTS:
MEASUREMENTS:
● Typically electrical power OK, tons not OK.
MEASUREMENTS:
● Typically electrical power OK, tons not OK.
● Uncertainty in a typical Btu measurement is in the
range of improvements one is trying to achieve.
MEASUREMENTS:
● Typically electrical power OK, tons not OK.
● Uncertainty in a typical Btu measurement is in the
range of improvements one is trying to achieve.
● Temperature measurements
MEASUREMENTS:
● Typically electrical power OK, tons not OK.
● Uncertainty in a typical Btu measurement is in the
range of improvements one is trying to achieve.
● Temperature measurements
● Flow rate measurements.
MEASUREMENTS:
● Typically electrical power OK, tons not OK.
● Uncertainty in a typical Btu measurement is in the
range of improvements one is trying to achieve.
● Temperature measurements
● Flow rate measurements.
● Improving measurements may amount to a third of the
total effort.
CONCLUSIONS:
CONCLUSIONS: ● 0.63 kW/ton a yearly average compared with 0.8
kW/ton baseline.
CONCLUSIONS: ● 0.63 kW/ton a yearly average compared with 0.8
kW/ton baseline.
● With 11 bill tons annual cooling load, we used 8.8 mil
kWh before and 6.93 kWh after.
CONCLUSIONS: ● 0.63 kW/ton a yearly average compared with 0.8
kW/ton baseline.
● With 11 bill tons annual cooling load, we used 8.8 mil
kWh before and 6.93 kWh after.
● Annual savings 1.87 mill kWh = $225,000
CONCLUSIONS: ● 0.63 kW/ton a yearly average compared with 0.8
kW/ton baseline.
● With 11 bill tons annual cooling load, we used 8.8 mil
kWh before and 6.93 kWh after.
● Annual savings 1.87 mill kWh = $225,000
● Additional energy savings thanks to the improved
functionality (maintaining a desired chilled water
temperature and pressure differential).
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Eff
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[k
W/t
on
]
Time [h]
Loop Efficiency September 2014
Measured: Average 0.64 kW/ton
Baseline: 0.8 kW/ton
Linear (Measured: Average 0.64 kW/ton)
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Eff
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W/t
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Time [h]
Loop Efficiency June 2015
Measured: Average 0.625 kW/ton
Baseline: 0.8 kW/ton
Linear (Measured: Average 0.625
kW/ton)
CONCLUSIONS:
CONCLUSIONS:
REMAINS TO BE DONE:
CONCLUSIONS:
● What we have achieved is a near optimum and further
improvements are to be done in both areas of control
(optimize the loop and optimize individual chillers).
REMAINS TO BE DONE:
CONCLUSIONS:
● What we have achieved is a near optimum and further
improvements are to be done in both areas of control
(optimize the loop and optimize individual chillers).
● About 70% of the expected total improvement in
efficiency achieved , 30% remains to be done.
REMAINS TO BE DONE:
THANK YOU!