4_Chiller Plant Controls for High Efficiency.pdf

Optimization in HVAC System

1. 1
Chiller Plant Control

2. Introduction to Trane Control Systems
2
© 2010 Trane
What We Will Cover •
Factory-integrated controls on chillers
•
Chiller plant control strategies
•
Tracer control features
•
Reliability and serviceability
•
Chiller plant optimization
•
Additional discussion

3. Introduction to Trane Control Systems
3
© 2010 Trane
Trane AdaptiView
™
Control System
4th Generation Microprocessor Chiller Control •
Adaptive control
–
Reliable operation through difficult
operation conditions
•
Feed-forward control
–
Accurate and stable control under
the most dynamic system transients
•
Sophisticated diagnostics
•
Fast restarts
•
Operator tested – informative display
•
Multiple open protocol communication options

4. Introduction to Trane Control Systems
4
© 2010 Trane
Feed-forward control enables the chiller to respond
faster to load changes
•
Feed-forward control uses flow change and entering water
temperature as an indication of load change
•
It proactively compensates for load changes
Trane AdaptiView
™
Control System
Feed-forward Control

5. Introduction to Trane Control Systems
5
© 2010 Trane
PID
Feedback
42º ?º
Typical Controller
Trane
UC800/AdaptiView
UC800
Feedback
40º 56º
Feedforward
ΣΣΣΣ
DP
627 gpm
•
Return Water Temp
•
Evaporator Flow
Trane AdaptiView
™
Control System
Feed-forward Control

6. Introduction to Trane Control Systems
6
© 2010 Trane
•
Directly measures chilled water flow
•
Enhances leaving water temperature control during
rapid flow rate changes of up to 50%/min.
–
>30 % /min commercial control
–
10% /min precision process control
•
Auto-tunes control gains to maintain stability and
accuracy over chiller’s full range of flow rates.
Trane AdaptiView
™
Control System
Variable Flow Compensation

7. Introduction to Trane Control Systems
7
© 2010 Trane
What Do Customers ReallyCare About ? •
Reliable chilled water flow
•
Operating cost (energy efficiency)
•
Operator safety
•
Environmental awareness
•
Reduced maintenance cost

8. Introduction to Trane Control Systems
8
© 2010 Trane
Tracer Chiller Plant Control
•
Repeatability – performance from plant to plant
–
Maximize the use of pre-engineered features
–
Minimize on-site customization
•
Flexibility – supports a variety of:
–
Plant layouts
–
Chiller types
–
Control strategies
•
Maximized energy savings
–
Load matching
–
Chiller tower optimization
–
Distributed pump pressure optimization
–
Thermal ice storage
–
Minimize manual intervention
•
Minimized operational costs
–
Minimize manual intervention, but anticipate it
–
Maintain chilled water flow and temperature
–
Minimize service surprises

9. Introduction to Trane Control Systems
9
© 2010 Trane
Load
Determination
Chiller Plant Control
Chiller
Sequencing
Chiller Plant Control
User
Interface
System
Optimization

10. Introduction to Trane Control Systems
10
© 2010 Trane
Plant Layout Flexibility Constant Flow
Chiller #1
Chiller #2
CW Supply
Temp
CW Return
Temp
UCP2
UCP2
UCP2
UCP2

11. Introduction to Trane Control Systems
11
© 2010 Trane
Plant Layout Flexibility Variable Flow -Decoupled
Air Handling Units
Control
Valves
Variable-Speed
Drive
Pressure
Differential
Controller or
Transmitter
Production
Distribution
Bypass Line
SUPPLYDEMAND
Chiller #1
Chiller #2
UCP2
UCP2
UCP2
UCP2

12. Introduction to Trane Control Systems
12
© 2010 Trane
Plant Layout Flexibility Variable Primary Flow
Air Handling Units
Control Valves
Production
Distribution
Bypass Line
S
UPPLYDEMAND
Variable-Speed
Drive
Flow
Meter
UCP2
UCP2
UCP2
UCP2
Differential Pressure
Sensor or
Transmitter

13. Introduction to Trane Control Systems
13
© 2010 Trane
Pre-engineered Features •
Load determination
•
Capacity matching
•
Rotation
•
Chiller setpoint control
•
Failure recovery
•
User interface
Installation and operating reliability and efficie ncy

14. Introduction to Trane Control Systems
14
© 2010 Trane
Load Determination (when to add or subtract a chiller) What is the optimal sequencing for chillers? •
Should I run one chiller at 100% or two chillers at 50%?
•
The givens…
–
whether you run one chiller or two…

The building load does not change

The outside wet bulb temperature does not change
–
When you run two chillers…

You maydouble the number of pumps

You maydouble the number of tower cells

15. Introduction to Trane Control Systems
15
© 2010 Trane
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
0 20 40 60 80 100
Percent Load
kW/ton
One Chiller at 100%? or
Two Chillers at 50%?
Constant Speed Centrifugal Chiller
Unloading at constant
condenser water temperature

16. Introduction to Trane Control Systems
16
© 2010 Trane
Capacity Matching (turn the right chiller on) Dependent on chiller plant design •
Normal -identical chillers
•
Base -heat recovery/super efficient
•
Pea -back up/alternate energy source/inefficient
•
Swing -match the load!
•
Custom -mix and match/nested CPC objects
Reduce operating costs

17. Introduction to Trane Control Systems
17
© 2010 Trane
UCP2
450 Ton Chiller
(Swing)900 Ton Chiller
(Normal-1)
900 Ton Chiller
(Normal-2)
UCP2
UCP2
02250 450
1800 1350 900UCP2
Building Load (Tons)
Reduce operating costs

18. Introduction to Trane Control Systems
18
© 2010 Trane
Flexible Rotation Which chiller is next?
•
Schedule based
•
Run-time
•
Manual operator decision
•
Customized
–
Number of starts
–
Other?
Reliable chilled water

19. Introduction to Trane Control Systems
19
© 2010 Trane
Unload Before Start Keep chillers online •
Ride out flow transients on startups
–
Deals with less sophisticated chiller controllers
•
Variable flow / multiple pump systems
•
Low supply water temperatures
Reliable chilled water

20. Introduction to Trane Control Systems
20
© 2010 Trane
Failure Recovery Keep chilled water flowing
•
No manual intervention required
•
Follow the standard sequence
•
Multiple failure inputs
–
Chiller level
–
System level
Reliable chilled water

21. Introduction to Trane Control Systems
21
© 2010 Trane
Intuitive User Interface
•
Minimize training time
•
Minimize undesirable manual control
•
Maximize operator efficiency
Reduced Operational Costs

22. Introduction to Trane Control Systems
22
© 2010 Trane
Chiller -Tower Optimization Tower Setpoint Optimization
•
Load
•
Condenser water
temperature •
Wet bulb
•
Tower design
•
Load
•
Condenser water
temperature •
Chiller design

23. Introduction to Trane Control Systems
23
© 2010 Trane
Chiller -Tower Optimization Chiller–Tower Interaction
Condenser Water Temperature, °°°°F
400
74
Energy Consumption, kW
76 78 80 82 72
300
200
100
0
84
Tower
Optimal
control point
Chiller Total

24. Introduction to Trane Control Systems
24
© 2010 Trane
Chiller -Tower Optimization North America
350K
Annual Operating Cost, $ USD
300K
250K
200K
150K
100K
50K
0
Mexico City Orlando San Diego Toronto
55°°°°F Lvg Tower Optimal Control Design ECWT
Control Strategy

25. Introduction to Trane Control Systems
25
© 2010 Trane
Air Handling Units
Control
Valves
Pressure
Differential
Controller or
Transmitter
•
Critical valve reset
•
Benefits
–
Reduced pump energy
–
Better coil control
–
Extend pump life
Distribution Pumping Critical Valve Pressure Control
Reduce operating costs

26. Introduction to Trane Control Systems
26
© 2010 Trane
Chiller Plant Dashboard Details Daily Average Metrics
Pump Pressure
Pump Status
System and
Chiller Status
Chilled Water Temps
Tower Water Temps
System
Load
System
Efficiency
Pump
Flow

27. Introduction to Trane Control Systems
27
© 2010 Trane
Summary
Key points to remember •
Integrated chiller controls
–
Factory quality; better performance, efficiency
and serviceability; lower risk
•
Performance
–
Temperature control; reliability; extended equipmen t life;
automatic failure response
•
Efficiency
–
Lower energy and maintenance costs
•
Sustainability
–
Maintain performance over time
–
Document performance

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Thank you!