Please Plea se Mute Mut e Cell Cell Phon Phones-T es-Than hank k You You
r : Fundamentals & Optimization Julian R. de Bullet ASHRAE Distinguished Lecturer
Big Plant Layout ,
40/58 °F Chilled Water Water
48” Dia. Pipe
93/103 °F Cond. Water
180,000 USgpm Cond. Water ”
.
Big Plant Layout
Large Chilled Water Range Using 18°F
∆T
48” 48 ” Pi Pipe pe - $5 $500 00/f /ftt
5000 ft = $2 $2.5M
5800 58 00 hp @ 200’ 200’ he head ad ’ ∆T)
,
Lower The Supply Water Tem er erat atur ure e To Ba Bala lanc nce e LMTD
No Pump Or Pipe Savings From Lower SWT
Fan Savings
°
Full Load Vs. Annual Load Peak Peak Month Coolin g Lo ad Profile
Chiller Design
140 120 100 ) s n 80 o T ( d a 60 o L
40
0
1
3
5
7
9
1 1
1 3 Hours
1 5
7 1
1 9
2 1
2 3
Full Load Vs. Annual Load Same Chil ler, Base Loaded Accounting Fo r Condenser Relief
0.6
0.5
0.55 kW/ton A t A HRI Conditions 0.4
0.3
0.2
Chil ler W/ VFD, Base Loaded 0.1 Accounting Fo r Condenser Relief
Fully Loaded
W/C Centrifugal
W/C Centrifugal VFD
58%
Fans Pumps 13%
Design Performance
5%
Chiller 33%
Fans 43%
Pumps 22%
Annual Energy Usage
Tower 2%
Full Load Vs. Annual Load Summary
Full Load Or Daily Load Indicator Of Overall System Performance
There Is No Substitute For Annual Energy Analysis Crunching the numbers
Air Cooled vs. Water Cooled
Avoid Tower, Pump And Piping
No Water Cost For Tower
Higher kW Than Water Cooled Chillers
Compressor Work Tracks Drybulb Not Wetbulb
Very Good NPLVs
Excellent Choice For Schools With Reduced Summer Hours
Air Cooled Vs. Water Cooled Summary
May Not Be More Cost Effective
Water And Maintenance Costs
May Not Have Acceptable Life Cycle Analysis
Single Vs. Parallel Vs. Series
All Constant Flow Systems
All Have Same Total Pump Power
Single Chiller Design 52F Chilled Water e urn
800 Ton Load 3 Way Valves
2400 Usgpm 95F
2400 Usgp m Chil led Water Pump 67 kW
2400 Usgpm Condenser Water Pum p 33.5 kW
800 Ton Chiller 0.55 kW/ton
Cooling Tower 40 kW 85FSupply To Chill er
44F Chilled Water Supply
Parallel Chiller Design 800 Ton Load 54F Chilled Water e urn 2400 Usgpm Chil led Water Pump 67 kW
2400 Usgpm 95F
Two 1200 Usgpm Condenser Water Pumps 16.8 kW Each
Two Cool ing Towers 20 kW Each
85FSupply To Chill er
Two 400 Ton Chillers 0.55 kW/ton
44F Chilled Water Supply
Series Chiller Design 800 Ton Load 54F Chilled Water e urn 2400 Usgpm 95F
Two Coolin g Towers 20 kW Each
Two 1200 Usgpm Condenser Water Pumps 16.8 kW Each
2400 Usgpm Chilled 67 kW
Two Nominal 400 Ton Chill ers. Lag 1 Produces 440 Tons Lead 2 Produces 360 Tons
Lag Chiller
Lead Chiller
85FSupply To Chi ller
44F Chilled Water Supply
Series-Counterflow Chiller Design 800 Ton Load
54F Chilled Water Return
2400 Usgpm 95F One Cool ing Tower 40 kW . Chiller 1 Produc es 440 Tons Chiller 2 Produc es 360 Tons 2400 Usgpm Chilled 67 kW
To Lag Chill er
85FSupply To Lead Chill er
One 2400 Usgpm Condenser Water Pump 33.6 kW 44F Chilled Water Supply
Piping Diversity - 3 Way Valves Coil Bypass Line Flow Is Constant At Each Coil Delta T Changes With Load
CW Pump Sized For
44F Supply
Chiller
Chiller Sized For Peak Load
Coil 3 Way Valve
Two Way Valves Temperature Range Acro ss Load Remains Constant. Flow Varies With Load
CW Pump Sized For Chiller Flow Rate es gn
e a
Chiller Sized For Peak Load
Standard Primary Loop Layout 51.5F Return Water 51.5F
To Chi ller Two 400 Ton Chillers
480 gpm Flow Through
Each At 300 Tons
Decoupler
54F 44F
Building Load 600 Tons (50% Load)
(Balanced Load)
Chiller 1- On Two Primary Pumps
Flow
Each At 960 gpm
Chiller 2- On
Chiller 3- Off
Secondary Pump
Variable Flow Vs. Constant Flow Summary
Variable Flow Required For Systems Over 10 HP 6.4.3.1
Modulate Down To 50%
Exceptions
Where Minimum Flow Is Less Than Flow Required By Equipment And < 75HP
Variable Primary Flow Design
B ass Line Used to Ensure Minimum Flow Through Chillers
VFD Primary Pum p Appl y Diversi ty to Flow Use 2 Way Valves Flow Meter
Automatic Isolatin g Valves
Variable Flow Vs. Constant Flow 500000 450000
Pump Work Cut In Half
350000 300000 h W250000 k
Notice Pump Work Half Chil ler Work !
200000 150000 100000 50000 0 Chillers Variable Primar Flow
Pumps
Towers
2 Chiller Primar /Secondar Flow
Fans 2 Chiller Parallel Flow
Equipment - Performance
Improve Chiller Full Load kW/Ton From 0.55 To 0.45 7% Improvement In Operating Cost
Chiller Price Goes Up Exponentially
Run
Chiller kW/ton
Chiller ($/yr)
Pumps ($/yr)
Tow er Fan ($/yr)
S.A. Fan ($/yr)
Total ($/yr)
1
0.55 . 0.53 0.52 0.51 0.5 0.49 0.48 . 0.46 0.45
24,435 , 23,541 23,095 22,648 22,202 21,755 21,309 , 20,416 19,970
15,209 , 15,206 15,204 15,202 15,201 15,199 15,197 , 15,194 15,192
1,441 , 1,441 1,441 1,441 1,441 1,441 1,441 , 1,441 1,441
24,512 , 24,507 24,504 24,501 24,499 24,496 24,493 , 24,488 24,485
65,597 , 64,695 64,244 63,792 63,343 62,891 62,440 , 61,539 61,088
3 4 5 6 7 8 10 11
ARI Standard 550/590-98
Know your Standards!
O eratin Hours Are At Part Load
The New Industry ARI Standard -1998
Part Load Anal sis IPLV % Load
Old % Hrs
New % Hrs
75
39
42
50
33
45
25
11
12
Various 500 Ton Chillers
.6
.5
.505
V L P I
.403
.
.365 .337
.3 WSC
WDC
WSC w/VFD
Notes: WSC = Single Compressor Centrifugal Chiller WDC = Dual Com ressor Centrifu al Chiller VFD = Variable Frequency Drive
WDC w/VFD
Analyze your design!
Equipment - Properties
Different Chillers Operate Differently
VFD Chillers Need Condenser Relief
Duals Are Most Efficient At 50% Load
Absorption And Gas Driven Chillers Operate On a different Fuel
To Get Best Results
r r r u Than Full Load Performance
y
r
r
Single vs. Dual Compressor Chillers 1.2 1 0.8 o T / 0.6 W K 0.4
0.2 0 0
20
40
60
80
% Chiller Plant Load Two Single Chillers
Two Dual Chillers
100
Equipment Summary
Be Careful That High Performance u y r
Ask For A Couple Of Selections And Some Budget Pricing
Understand And Take Advantage Of Chillers Operating Properties
Range Vs. Supply Water Temperature
Flow (Usgpm) = Load (tons) x 24 / Temp. Range (F)
Increasing Range Reduces Flow
Reduces Pipe, Pump And Motor Size
.
Reducing Flow Reduces Pump Work
This Is A Good Goal
It Will Affect Every Part Of the Chilled Water System
Everything Must Be Considered
Range Vs. Supply Water Temperature
Fan Work Savings For Small Changes (2 to 4°F) Don’t Save Enough To Offset Chiller Penalty
20% Airflow Decrease
35% Static Decrease
49% Power Decrease
Don’t Lower Supply Water Temperature Just To
Don’t Lower To Ensure Design Water Temperature Will Be Available At Coil
If You Assume Water Will Be 2°F Warmer At Coil Then You Assume 20% Of Chiller Capacity Lost To Heat Gain!
Range Vs. Supply Water Temperature 97°F 118.3 psig R-134a
Standard ARI Conditions
10F Range
2F Approaches In Heat Exchangers
R E A T U
θ1
54- 44F Chilled Water Water
θ2
HEAT OF CONDENSATION
R S E E N N D
T2
95°F
P E R T E M U I D
F L
O
LIFT (°F)
85°F T1
54°F T1 C O O
L E R
θ1
F LU I D T EM P E R A T UR E
T2
HEAT OF VAPORIZATION
55F Lift On Compressor 42°F 36.6 psig R-134a
SATURATED SUCTION TEMPERATURE {TR}
44°F θ2
Range Vs. Supply Water Temperature
Change To 14F Range
Maintain Supply Water Temperature
Smaller Pumps, Pipes .
Improves Chiller Performance
Hurts Chilled Water Coil Performance
Deeper Coils Required
Increased Fan Static
Range Vs. Supply Water Temperature
Maintain 14F Range
ower upp y ater Temperature To 42F
4% Increase In Compressor Lift
Chiller Performance Suffers
Chilled Water Coil Performance
Range Vs. Supply Water Temperature
VAV Office Bldg In New York City
Fixed Supply Water Temperature
Increase Chilled Water Range From 10 To 24F
Fan Motor Goes From 94.8 HP To 114.7 HP (21%)
Pump Goes From 38.5 HP to 16 HP (58%)
Run
Chiller Chilled Water Capaci ty Perform Tem p Range Tons KW/ton (°F)
1
400
3 4 5 6 7 8
400 400 400 400 400 400
0.546 . 0.547 0.547 0.543 0.543 0.543 0.543
10 14 16 18 20 22 24
Pum p HP 38.5 . 27.5 24 21.4 19.2 17.5 16
Coil APD Row s/fi ns TSP (in. w .c.) (in. w .c.) 0.62 . 0.7 0.79 0.87 0.94 1.1 1.25
5/10 6/10 6/12 8/9 8/11 10/10 12/10
3 . 3.08 3.15 3.25 3.32 3.48 3.63
Fan Total otor si ze Pow er (HP) (HP) 94.8 97.3 99.5 102.7 104.9 109.9 114.7
426.1 . 417.6 416.3 415.3 415.3 418.6 421.9
Range Vs. Supply Water Temperature
Fixed Supply Water Temperature
Increase Chilled Water Ran e From 10 to 24F
Annual Energy Analysis
System Peaks At 16F Range
Run C.W. Range (°F) 1 2 3
10 12 14
5 6 7 8
18 20 22 24
Chiller ($/yr)
Pumps ($/yr)
26,074 26,096 26,167 , 26,081 26,126 26,259 26,358
15,175 13,784 12,792 , 11,489 11,034 10,784 10,487
Tower Fan S.A. Fan ($/yr) ($/yr) 1,591 1,593 1,594 , 1,601 1,604 1,619 1,625
28,275 28,560 28,846 , 30,070 30,574 31,726 32,810
Total ($/yr) 71,115 70,033 69,399 , 69,241 69,338 70,388 71,280
Range Vs. Supply Water Temperature
Switch To Constant Volume With Reheat
Increase Chilled Water Range From 10 to 24F
System Peaks At 14F
Run
Fan Penalty Outweighs Pump Savings
1 2 3 4 5 6
C.W. Range ° 10 12 14 16 18 20
8
24
Chi ll er
Pum ps
40,035 40,034 40,224 40,327 40,174 40,285 , 40,772
19,842 18,013 16,728 15,765 15,025 14,429 , 13,692
Tow er Fan S.A. Fan 2,821 2,821 2,831 2,839 2,852 2,863 , 2,912
70,957 71,954 72,396 73,657 75,455 76,715 , 82,283
Total 133,655 132,822 132,179 132,588 133,506 134,292 , 139,659
Range Vs. Supply Water Temperature
Declining Supply Water Temperature (44 To 38F)
Increase Chilled Water Range From 10 To 24F
Annual Energy Analysis
System Peaks At 16F Range And 42F SWT
Run 1 2 3 3 4 5 6 7
C.W. Range C.W. S.T. (°F) (°F) 10 12 16 14 16 18 20 22
Not As Good As 16F Range And 44F SWT!
44 44 44 42 42 40 40 38
Chiller ($/yr)
Pumps ($/yr)
26,074 26,096 26,211 27,733 27 779 29,371 29,351 30,365
15,175 13,784 12,055 12,790 12 039 11,462 11,002 10,623
Tower Fan S.A. Fan ($/yr) ($/yr) 1,591 1,593 1,597 1,593 1 593 1,594 1,596 1,596
28,275 28,560 29,350 28,573 28 570 28,584 28,872 28,881
Total ($/yr) 71,115 70,033 69,213 70,689 69 981 71,011 70,081 71,465
Condenser Water Range
Increase Condenser Water Range From 10 To 15F
System Peaks At 10 Range
It Costs More To Operate A System At Higher Ranges
Run
Cond .W. Range
Chi ll er yr
Pum ps yr
1 2 3
10 11 12
5 6
14 15
26,074 27,084 27,517 , 28,527 29,057
15,175 14,562 14,049 , 13,245 12,923
Tow e r Fan S .A. Fan yr yr 1,591 1,592 1,592 , 1,592 1,593
28,275 28,283 28,286 , 28,293 28,297
Total yr 71,115 71,521 71,444 , 71,657 71,870
Condenser Water Relief
Optimizing Starter Selections
Try Different Starters Solid
State Starters Have Different Size Breaks Than Wye Delta Starters
o tate tarters Are Now eaper In Most Cases - Try Both Ways De endin U on Size Breaks
Try
Unit Mounted And Free Standing Size Breaks Can Make Different Selections Appear
Check
VFD Sizing –Expensive At Very
Annual WB In Major US Cities 80.0 70.0 60.0 50.0 40.0 30.0 20.0
Strong Candi dates For VFD Chill ers
10.0 -
y y a r a r u u r n b J a F e
h c a r M
l i r A p
Los Angeles
a y M
n e J u
l y J u
Washington DC
t r r e r e r u s b e b e b b g o e m c e m A u p t e m O c t o v e N D e S Atlanta
Chicago
Miami
AVAILABILITY OF REFRIGERANT (Dupont & ICI Projections) M Tonnes (000) 300 250 200
HFC134a HCFC22
HFC410A
100 50
HCFC123 1995
2000
2005
2010
2015
Year
2020
2025
2030
