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Please Mute Cell Phones-Thank You Chiller Plant: Fundamentals & Optimization Julian R. de Bullet ASHRAE Distinguished Lecturer [email protected]...

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Please Mute Cell Phones-Thank You

Chiller Plant: Fundamentals & Optimization Julian R. de Bullet ASHRAE Distinguished Lecturer [email protected]

Big Plant Layout  60,000 60 000 Tons  40/58 °F Chilled Water  80,000 USgpm Chilled Water  48” Dia. Pipe

 93/103 °F Cond. Water  180,000 USgpm Cond. Water  54” Dia. Dia Pipe

Big Plant Layout  Large Chilled Water Range Is a Must  Using 18°F ∆T  48” Pipe - $500/ft  5000 ft = $2.5M  5800 hp @ 200’ head  (It’s (It s Over 10 10,000 000 hp @ 10 10°F F ∆T)

 Lower The Supply Water Temperature To Balance LMTD  No Pump Or Pipe Savings From Lower SWT  Fan Savings

Full Load Vs. Annual Load Peak Month Cooling Load Profile

Chiller Design Performance

140 120

80 60 40 20

Hours

23

21

19

17

15

13

11

9

7

5

3

0

1

Load d(Tons)

100

Full Load Vs. Annual Load Same Chiller, Base Loaded Accounting For Condenser Relief

0.6

0.5

0.55 kW/ton At AHRI Conditions 0.4 0.3

0.2

Chiller W/ VFD, Base Loaded 0.1 Accounting For Condenser Relief 0

Fully Loaded

W/C Centrifugal

W/C Centrifugal VFD

Full Load Vs. Annual Load Chiller 58%

Fans 24% Pumps 13%

Design Performance

Tower 5%

Chiller 33%

Fans 43%

Pumps 22%

Annual Energy Usage

Tower 2%

Full Load Vs. Annual Load Summary  Full Load Or Daily Load Profiles Are A Poor 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

 Water Cooled Is More Energy Efficient  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 R t Return

800 Ton Load 3 Way Valves

2400 Usgpm 95F

2400 Usgpm Chilled Water Pump 67 kW

2400 Usgpm Condenser Water Pump 33.5 kW

800 Ton Chiller 0.55 kW/ton

Cooling Tower 40 kW 85FSupply To Chiller

44F Chilled Water Supply

Parallel Chiller Design 800 Ton Load 54F Chilled Water R t Return 2400 Usgpm Chilled Water Pump 67 kW

2400 Usgpm 95F

Two 1200 Usgpm Condenser Water Pumps 16.8 kW Each

Two Cooling Towers 20 kW Each

85FSupply To Chiller

Two 400 Ton Chillers 0.55 kW/ton

44F Chilled Water Supply

Series Chiller Design 800 Ton Load 54F Chilled Water R t Return 2400 Usgpm 95F

Two Cooling Towers 20 kW Each

Two 1200 Usgpm Condenser Water Pumps 16.8 kW Each

2400 Usgpm Chilled Water Pump 67 kW

Two Nominal 400 Ton Chillers. Lag 1 Produces 440 Tons Lead 2 Produces 360 Tons

Lag Chiller

Lead Chiller

85FSupply To Chiller

44F Chilled Water Supply

Series-Counterflow Chiller Design 800 Ton Load

54F Chilled Water Return

2400 Usgpm 95F One Cooling Tower 40 kW Two Nominal 400 Ton Chillers. Chillers Chiller 1 Produces 440 Tons Chiller 2 Produces 360 Tons 2400 Usgpm Chilled Water Pump 67 kW

89F Supply To Lag Chiller

85FSupply To Lead Chiller

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 Connected Flow

44F Supply

Chiller

Chiller Sized For Peak Load

Coil 3 Way Valve

Two Way Valves Temperature Range Across Load Remains Constant. Flow Varies With Load

CW Pump Sized For Chiller Flow Rate At D Design i D Delta lt T

Chiller Sized For Peak Load

2 Way Valve

Standard Primary Loop Layout 51.5F Return Water To Chiller Two 400 Ton Chillers Each At 300 Tons (Balanced Load)

Chiller 1- On Two Primary Pumps Each At 960 gpm

51.5F 480 gpm Flow Through Decoupler

54F 44F

Building Load 600 Tons (50% Load)

Flow

Chiller 2- On 44F

Chiller 3- Off

Secondary Pump 1440 gpm

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

Bypass yp Line Used to Ensure Minimum Flow Through Chillers

VFD Primary Pump Apply Diversity to Flow Use 2 Way Valves Flow Meter

Automatic Isolating Valves

Variable Flow Vs. Constant Flow 500000 450000 400000

Pump Work Cut In Half

350000

kWh

300000 250000

Notice Pump Work Half Chiller Work!

200000 150000 100000 50000 0 Chillers Variable Primary y Flow

Pumps

Towers

2 Chiller Primary/Secondary y y Flow

Fans 2 Chiller Parallel Flow

Equipment - Performance  Improve Chiller Full Load kW/Ton From 0.55 To 0.45  An 18% Improvement In Chiller Provides Only 7% Improvement In Operating Cost  Chiller Price Goes Up Exponentially Run 1 2 3 4 5 6 7 8 9 10 11

Chiller kW/ton 0.55 0 54 0.54 0.53 0.52 0.51 0.5 0.49 0.48 0 47 0.47 0.46 0.45

Chiller ($/yr) 24,435 23 988 23,988 23,541 23,095 22,648 22,202 21,755 21,309 20 863 20,863 20,416 19,970

Pumps ($/yr) 15,209 15 207 15,207 15,206 15,204 15,202 15,201 15,199 15,197 15 196 15,196 15,194 15,192

Tower Fan ($/yr) 1,441 1 441 1,441 1,441 1,441 1,441 1,441 1,441 1,441 1 441 1,441 1,441 1,441

S.A. Fan ($/yr) 24,512 24 509 24,509 24,507 24,504 24,501 24,499 24,496 24,493 24 491 24,491 24,488 24,485

Total ($/yr) 65,597 65 145 65,145 64,695 64,244 63,792 63,343 62,891 62,440 61 991 61,991 61,539 61,088

ARI Standard 550/590-98

Know y your Standards!

99% Of All Operating p g Hours Are At Part Load

The New Industry ARI Standard -1998

Part Load Analysis y (IPLV) ( ) % Load

Old % Hrs

New % Hrs

100

17

1

75

39

42

50

33

45

25

11

12

Systems Solution

Various 500 Ton Chillers

.6

.505

IPLV

.5

.403

.4 4

.365 .337

.3 WSC

WDC

WSC w/VFD

Notes: WSC = Single Compressor Centrifugal Chiller p Centrifugal g Chiller WDC = Dual Compressor 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

 System Must Take Advantage OF Chiller Properties To Get Best Results  Pa Partt Load Pe Performance fo mance Is Us Usually all Mo More e Important Impo tant Than Full Load Performance

Single vs. Dual Compressor Chillers 1.2 1

KW/Ton n

0.8 0.6 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 Equipment Can Pay For Itself  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

 Pump Power (hp) = Flow (Usgpm)x Head (ft) / 3960 x Eff. Eff  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  Especially For VAV  20% Airflow Decrease  35% Static Decrease  49% Power Decrease

 Don’t Lower Supply Water Temperature Just To Save Fanwork  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 θ1

 54- 44F Chilled Water  85 - 95F Condenser Water

 10F Range  2F Approaches In Heat Exchangers

θ2

HEAT OF CONDENSATION

E NS DE N CO LIFT (°F)

DT L UI F R

URE RAT E P EM

T2

95°F

85°F T1

54°F T1 CO O

θ1

 55F Lift On Compressor

L ER

FLU ID

TEM P

ERAT U

RE

T2

HEAT OF VAPORIZATION

42°F 36.6 psig R-134a

SATURATED SUCTION TEMPERATURE {TR}

44°F

θ2

Range Vs. Supply Water Temperature  Change To 14F Range  Smaller Pumps, Pipes etc. etc

 Maintain Supply Water Temperature  LMTD Increases  Improves Chiller Performance

 Hurts Chilled Water Coil Performance  Deeper Coils Required  Increased Fan Static Pressure

Range Vs. Supply Water Temperature  Maintain 14F Range  L Lower S Supply l W Water Temperature To 42F  4% Increase In Compressor Lift  Chiller Performance Suffers

 Chilled Water Coil Performance Improves

Range Vs. Supply Water Temperature  VAV Office Bldg In New York City  Fixed Supply Water Temperature  Design Conditions  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 1 2 3 4 5 6 7 8

Chiller Chilled Water Capacity Perform Temp Range Tons KW/ton (°F) 400 0.546 10 400 0 546 0.546 12 400 0.547 14 400 0.547 16 400 0.543 18 400 0.543 20 400 0.543 22 400 0.543 24

Pump HP 38.5 32 1 32.1 27.5 24 21.4 19.2 17.5 16

Coil Fan Total APD Rows/fins TSP Motor size Power (in. w.c.) (in. w.c.) (HP) (HP) 0.62 5/10 3 94.8 426.1 0 66 0.66 5/11 3 04 3.04 96 420 9 420.9 0.7 6/10 3.08 97.3 417.6 0.79 6/12 3.15 99.5 416.3 0.87 8/9 3.25 102.7 415.3 0.94 8/11 3.32 104.9 415.3 1.1 10/10 3.48 109.9 418.6 1.25 12/10 3.63 114.7 421.9

Range Vs. Supply Water Temperature  Fixed Supply Water Temperature  Increase Chilled Water Range From 10 to 24F  Annual Energy Analysis  System Peaks At 16F Range Run C.W. Range (°F) 1 10 2 12 3 14 4 16 5 18 6 20 7 22 8 24

Chiller ($/yr) 26,074 26,096 26,167 26 211 26,211 26,081 26,126 26,259 26,358

Pumps Tower Fan S.A. Fan ($/yr) ($/yr) ($/yr) 15,175 1,591 28,275 13,784 1,593 28,560 12,792 1,594 28,846 12 055 12,055 1 597 1,597 29 350 29,350 11,489 1,601 30,070 11,034 1,604 30,574 10,784 1,619 31,726 10,487 1,625 32,810

Total ($/yr) 71,115 70,033 69,399 69 213 69,213 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  Annual Energy Analysis  System Peaks At 14F  Fan Penalty Outweighs Pump Savings

Run 1 2 3 4 5 6 7 8

C.W. Range ((°F) F) 10 12 14 16 18 20 22 24

Chiller ($/yr) 40,035 40,034 40,224 40,327 40,174 40,285 40 526 40,526 40,772

Pumps Tower Fan S.A. Fan ($/yr) ($/yr) ($/yr) 19,842 2,821 70,957 18,013 2,821 71,954 16,728 2,831 72,396 15,765 2,839 73,657 15,025 2,852 75,455 14,429 2,863 76,715 13 963 13,963 2 884 2,884 79 595 79,595 13,692 2,912 82,283

Total ($/yr) 133,655 132,822 132,179 132,588 133,506 134,292 137 193 137,193 139,659

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 44 12 44 16 44 14 42 16 6 42 18 40 20 40 22 38

Not As Good As 16F Range And 44F SWT!

Chiller ($/yr) 26,074 26,096 26,211 27,733 27,779 , 9 29,371 29,351 30,365

Pumps Tower Fan S.A. Fan ($/yr) ($/yr) ($/yr) 15,175 1,591 28,275 13,784 1,593 28,560 12,055 1,597 29,350 12,790 1,593 28,573 12,039 ,039 1,593 ,593 28,570 8,5 0 11,462 1,594 28,584 11,002 1,596 28,872 10,623 1,596 28,881

Total ($/yr) 71,115 70,033 69,213 70,689 69,981 69,98 71,011 70,081 71,465

Condenser Water Range  Increase Condenser Water Range From 10 To 15F  Annual Energy Analysis  System Peaks At 10 Range  It Costs More To Operate A System At Higher Ranges

Run 1 2 3 4 5 6

Cond .W. Range (°F) 10 11 12 13 14 15

Chiller ($/ ) ($/yr) 26,074 27,084 27,517 28 094 28,094 28,527 29,057

Pumps Tower Fan S.A. Fan ($/ ) ($/yr) ($/ ) ($/yr) ($/ ) ($/yr) 15,175 1,591 28,275 14,562 1,592 28,283 14,049 1,592 28,286 13 616 13,616 1 592 1,592 28 290 28,290 13,245 1,592 28,293 12,923 1,593 28,297

Total ($/ ) ($/yr) 71,115 71,521 71,444 71 592 71,592 71,657 71,870

Condenser Water Relief

Optimizing Starter Selections  Try Different Starters

Solid State Starters Have Different Size Breaks Than Wye Delta Starters Solid S lid S State S Starters Are A Now N Ch Cheaper In Most Cases - Try Both Ways Depending p g Upon p Size Breaks Try Unit Mounted And Free Standing Size Breaks Can Make Different Selections Appear Check VFD Sizing –Expensive At Very Bottom Of Amp Rating

Annual WB In Major US Cities 80.0 70.0 60.0 50.0 40.0 30.0

Strong Candidates For VFD Chillers

20.0 10.0

Los Angeles

Washington DC

Atlanta

Chicago

be r

ec em

be r D

ov em

N

r

ct ob er O

Se pt em be

Au gu st

Ju ly

Ju ne

ay M

Ap ril

ar ch M

Ja nu ar y Fe br ua ry

-

Miami

AVAILABILITY OF REFRIGERANT (Dupont & ICI Projections) M Tonnes (000) 300 250 200

HFC134a 150

HCFC22

HFC410A

100 50 0

HCFC123 1995

2000

2005

2010

Year

2015

2020

2025

2030

THANK YOU!