1 pumping system fundamentals 2014 jeff turner systecore inc

1

Pumping System Fundamentals

2014

Jeff Turner

Systecore Inc.

www.systecoreinc.com

www.michigansteam.com

http://www.systecoreinc.com/

http://www.michigansteam.com/

2

Overview

Welcome

• Pumping Review

• Piping Review

3

Back to theBasics!

4

Pump Review

• Pump Sizing

• Pump Types

• Parallel Pumping

• Series Pumping

• Other Cautions

5

Pumping Sizing

PRO-MAX® Series Pumps

6

1. Capacity (flow) varies as the rotating speed : FLOW 2 = FLOW ( SPEED 2 / SPEED 1) 2. Head (pressure) varies as the square of the rotating speed : HEAD 2 = HEAD 1 (SPEED 2 / SPEED 1)

2

3. Brake horsepower (BHP) varies as the cube of the rotating

speed :

BHP 2 = BHP 1 (SPEED 2 / SPEED 1)3

Affinity Laws

7

How does it work?

RotationImpeller

Blades

VtVr

Vs

Vr = Radial VelocityVt = Tangential VelocityVs = Vector Sum Velocity

Full Trim Impeller...

8

How does it work?

Rotation

FullImpeller

ReducedImpeller

VtVr

Vs ReducedVelocity

Partially Trimmed Impeller...

9

Affinity Laws

• Capacity varies as the ratio of the diameters.

• Head varies as the ratio of the square of the diameters.

• Brake horsepower varies as the ratio of the cube of the diameters.

10

1201101009080706050403020 14013010

4

24

20

16

12

8

H.[FT]

US.gpm

50%60%

70%

70%

75%

75%

79%

Adjustment of the Pumping CapacityTrimming Impellers?

Why Not?

• Decreases Pump Efficiency

• One Way Trip

•VSD’s

11

Affinity Laws

SpeedFlow/

VolumeHead

HorsepowerRequired

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

100%

81%

64%

49%

36%

25%

16%

9%

4%

1%

0%

100%

73%

51%

34%

22%

13%

6%

3%

-

-

-

12

Affinity Laws for Centrifugal Pumps

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70 80 90 100

Flow/Speed, Percent

Per

cen

t

Flow

Head

Horsepower

Affinity Laws

13

What’s on a Pump Curve?• Flow, gpm

• Head, feet

• Efficiency curves

• Impeller trims

• Horsepower curves

• NPSH Curve

• Pump speed

• Non-overloading value, minimum flow

14

Example Selection Point• Flow = 1000 gpm

• Head = 90 feet

What then?

• Pump Curve Booklet

• Software

• Websites

• Select: 5” End Suction Pump

17

Detail Report -‘Standard Efficiency’ Motor

Centrifugal Pump - Detail Report Pump Series: HVES Pump Size: E4N11A-2 Performance Rank: 1 Pump Speed: 1750 Total Capacity: 1000.0 gpm Total Head: 90.0 Feet Efficiency: 85.8 pct NPSH req: 11.7 Feet Discharge Size: 4.000 in Velocity: 18.03 fps Suction Size: 6.000 in Velocity: 11.10 fps Impeller Diameter: 10.815" PRV Size: Max BHP: 30.00 (at design: 67.21 pct) Pump Power, BHP: 26.7 ( 21.99 Kw) Motor Power, HP: 40.00 (BHP/HP = 0.74)

Choose ‘non-overloading’ motor

18

Detail Report -‘Standard Efficiency’ Motor

Motor: SE AC MOTOR 230/460V 324T SC R 363853 40.000 HP 1771 RPM 4 poles 60 Hz 3 phase Voltage: 230 RPM: 1777.89 Eff: 90.94 AMP: 72.15 P.F.: 84.12 KVA: 28.74 Annual Operating Cost: $21179.82 for 8760.0 hours annually at $0.10/Kwh

19

Detail Report -‘High Efficiency’ Motor

Motor: Century E+ AC MOTOR 230/460V SCE S324T DPE E600 40.000 HP 1770 RPM 4 poles 60 Hz 3 phase Voltage: 460 RPM: 1784.31 Eff: 93.38 AMP: 35.31 P.F.: 83.70 KVA: 28.14

Annual Operating Cost: $20627.78 for 8760.0 hours annually at $0.10/Kwh

20

Operating Cost Comparison

Standard Efficiency $21,180

High Efficiency $20,628

Annual Savings $ 552

(@ $0.10/kWh)

21

Pumping system

Sources of pressure drop

• Pipe

• Fittings

• Valves

• Coils

• Source (boiler or chiller)

22

System Curve

Head varies as the square

of the flow.

23

Impeller Change/Flow, Percent

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Pe

rce

nt

of

De

sig

n H

ea

d

Head

System Curve

24

What Impacts the System Head?

• Actual component pressure drops

• Actual piping loses

• Present vs. future loads

• Safety Factors

• Heating vs. cooling flow

26

Jeff’s 1st Law

Pumps are stupid.

Pumps don’t know flow...

Pumps don’t know temperature...

...it will deliver as much flow as it can based on the system resistance it sees.

27

Pump Over-heading

• Balance System?

• Close Valve @ Pump?

• Trim the impeller?

• Adjustable Frequency Drive?

28

Why Trim the Impeller?Centrifugal Pump - Detail Report Pump Series: HSC Pump Size: S5A12A-2 Performance Rank: 2 Pump Speed: 1750 Total Capacity: 1000.0 gpm Total Head: 55.0 Feet Efficiency: 77.58 pct NPSH req: 10.72 Feet Discharge Size: 4.000 in Velocity: 18.03 fps Suction Size: 6.000 in Velocity: 11.10 fps Impeller Diameter: 9.375" PRV Size: Max BHP: 18.19 (at design: 78.20 pct) Pump Power, BHP: 17.80 ( 13.39 Kw) Motor Power, HP: 20.00 (BHP/HP = 0.90)

29

Standard efficiency

Why Trim the Impeller?

Motor: Century AC MOTOR 230/460V S256T SC DP R419 20.000 HP 1750 RPM 4 poles 60 Hz 3 phase Voltage: 460 RPM: 1759.44 Eff: 87.78 AMP: 21.86 P.F.: 87.57 KVA: 17.42


30

High efficiency

Why Trim the Impeller?

Motor: Century E+ AC MOTOR 230/460V SCE 256T DPE E401 20.000 HP 1700 RPM 4 poles 60 Hz 3 phase Voltage: 460 RPM: 1761.91 Eff: 90.28 AMP: 22.33 P.F.: 83.36 KVA: 17.79


31

Operating Cost Comparison-High Efficiency Motor + Trimming Impeller

Std Eff Hi Eff Difference

@100 Ft $21180 $20628 $552

@ 55 ft 13362 12992 $370

Difference $ 7818 $ 7636 $8188

32

The Effects of Glycol on Pump Selection

33

Sample Problem

• The calculations are based on 1,000 gpm of water to the process, and as such designed the system utilizing 8 inch pipe & 6410 feet of pipe.

• A 5” pump is selected for 1000 gpm @ 90 feet of head.

• The correct impeller size is 10.8125” and the correct motor is 30 hp, nol.

8 in

1.56

6.42

6410

1.56

100

36

Centrifugal Pump - Detail Report

Pump Series: HVES Pump Size: E4N11A-2 Performance Rank: 2 Pump Speed: 1750 Total Capacity: 1000.0 gpm Total Head: 90.0 Feet Efficiency: 85.8 pct NPSH req: 11.70 Feet Discharge Size: 4.000 in Velocity: 18.03 fps Suction Size: 6.000 in Velocity: 11.10 fps Impeller Diameter: 11.250" Max BHP: 30.00 (at design: 79.50 pct) Pump Power, BHP: 26.7 ( 23.54 Kw) Motor Power, HP: 40.00 (BHP/HP = 0.79) --------------------------------------------------------------------- Motor: Century E+ AC MOTOR 230/460V SCE S324T DPE E600 40.000 HP 1770 RPM 4 poles 60 Hz 3 phase Voltage: 460 RPM: 1783.06 Eff: 93.43 AMP: 37.29 P.F.: 84.79 KVA: 29.71 --------------------------------------------------------------------- Annual Operating Cost: $22070.62 for 8760.0 hours annually at $0.10/Kwh

37

Sample Problem

• The new process requires fluid which is 50% propylene glycol at 45°F.

• What is the new head requirement?

• What is the new impeller and motor size for these conditions?

45 50

1.0513.21

0.00013542

1000 8 in.

6.42

2.29

6410

2.29

147

Centrifugal Pump - Detail Report Pump Series: 1510 Pump Size: 5G Performance Rank: 1 Pump Speed: 1750 Total Capacity: 1000.0 gpm Total Head: 147.0 Feet Efficiency: 82.99 pct NPSH req: 8.07 Feet Discharge Size: 5.000 in Velocity: 16.03 fps Suction Size: 6.000 in Velocity: 11.10 fps Impeller Diameter: 12.625" Max BHP: 51.68 (at design: 67.94 pct) Pump Power, BHP: 44.720 ( 33.35 Kw) Motor Power, HP: 60.00 (BHP/HP = 0.75) --------------------------------------------------------------------- Motor: Century E+ AC MOTOR 460V SCE Y364T DPE E716 60.000 HP 1775 RPM 4 poles 60 Hz 3 phase Voltage: 460 RPM: 1776.13 Eff: 92.79 AMP: 52.21 P.F.: 86.40 KVA: 41.60 --------------------------------------------------------------------- Annual Operating Cost: $31482.63 for 8760.0 hours annually at $0.10/Kwh

43

Sample Problem Results

• 5” pump must be selected for 1000 gpm @ 147 feet of head.

• The correct impeller size is 12.3125 inches and the correct motor is 60 horsepower (non-overloading).

44

Parallel Pump Operation

Total system head

1/2 system flow

1/2 system flow

45

Two pumpsin operation

Each pump

Head(ft)

Flow(gpm)


46

Parallel 6” Pump Curve

47

90

80

70

60

50

40

30

20

10

0 10 1009080706050403020

100

% F

ull Lo

ad

HP

% Flow

Parallel C/S2 Pumps

Single C/S

Single ParallelC/S


48

Series Pump Operation

Total system flow

1/2 system head per pump

49Flow (gpm)


Head (ft) Single pump curve


50Flow(gpm)


Each pumpHead

(ft)


51

Pump Types

52

•Basemounted•Vertical Inline•Vertical Turbine

Types of Pumps

53

Pump Size, in flow, gpm Head, ft HP Common Application

Vertical Turbine VTP 5-20 to 8000 175/stage to 500 Cooling towers, chiller pumps Inline (Inline) Series VIL 1 - 2½ to 180 to 62 to 3 Hydronic heating & cooling, general

service, industrial, & domestic water

SeriesVIL 1½ - 8 to 2500 to 400 to 60 Hydronic heating & cooling, general service, & industrial

Series VIL 1¼ - 2 to 220 to 225 to 2 Hydronic heating & cooling, general service, industrial, & cooling towers

End Suction (Floor Mounted) – Close and Long Coupled HVES 1¼ - 6 to 2800 to 530 to 125 Hydronic heating & cooling, general

service, & industrial

HVES-CC 1¼ - 6 to 2400 to 530 to 60 Hydronic heating & cooling, general service, & industrial

Horizontal Split (Base Mounted) HSC 2-10 to 6500 to 550 to 300 Hydronic heating & cooling, general

service, industrial, & cooling towers

Typical Size Range by Pump Type

54

• Pump types:– Basemounted

• Long & Close coupled, end suction

• Horizontal Split case, double suction

– Vertical Inline• Close coupled

• Spacer coupled

Centrifugal Pump Construction

55

Type HVESFrame Mounted End Suction


•Flows to 2,500 GPM•Heads to 400 ft. TDH•Delivery in 7 working days

56PRO-MAX® Series Pumps

•Flows to 2,500 GPM•Heads to 450 ft. TDH•Delivery in 7 working days•Space saving design

Type HVESClose Coupled End Suction

57

Type HSCHorizontal Split Case

•Flows to 6,000 GPM with larger ones on way•Heads to 160 ft. TDH•Optional 300 PSI W.P.•Delivery in 7 working days


58

Type VIL - Vertical Inline Pumps (Close Coupled)


•Flows to 2,500 GPM•Heads to 450 ft. TDH•Delivery in 7 working days•Space saving design

59

• Lineshaft– 88 Models

– 5-20” bowls

– 4 Styles

– 20 - 10,000 gpm

– 7 - 200 feet head

• Submersible– 48 Models

– 5 - 14” bowls

– 40 - 2000 gpm

– 25 - 300 feet head

Vertical Turbine Pumps

60

• Important considerations:– Manufacturing standards/Quality (ISO 9001)

– Serviceability, maintenance after turnover of project

– Availability of replacement parts/motors

– Effect of pump on system efficiency, flexibility for reconfiguration for future use.

– ASHRAE 90.1 - optimizing energy use of pump

– Pricing comparison between Basemount & V-I-L, an understanding the necessities for maintenance friendliness.


61

• Important considerations:– Hytrel (orange) versus EPDM (black) Couplers

– ANSI/OSHA Coupling Guard

– HVAC Pumps


6229

• Recommended installation:– Basemount

– Tie in with finished floor


6331

• Recommended installation:– Basemount

– Tie-in with finished floor impractical

– Spring/RSR isolation


64

Piping Review

• Why Variable Volume

• Primary-Secondary Piping

• Air Management

• Primary-Secondary Variations

65

Why Variable Volume?

1. Low return water temperatures.2. Robs chilled water from other coils atpart load conditions.3. Increases flow in primary piping.4. Adds additional chillers on line.5. Chiller performance is reduced.

3-Way Valve Systems:

66

Variable Volume Systems

• Permit Constant Volume Chiller Pumping

• Permit Variable Volume Load Pumping

67

Primary-secondary Pumping

Return

Supply

PumpController

Constant or Variable Speed Secondary Pumps

Primary-secondaryCommon

Chiller 3

Chiller 2

Chiller 1

Constant SpeedPrimary Pumps

Air Separator andExpansion Tank(s)

68

Jeff’s 2nd Law

More Pumps is Better!

69

HD

125

100

75

50

25

150

25 50 75 100

% Design Flow

Primary Pumps = V/V

Secondary Pumps +

Constant Flow Primary Pumps, only

Pump Head Comparison

70% Flow

125

100

75

50

25

150

25 50 75 100

HDVarying differential pressure absorbed by control valve

System resistance

TDH of pumpPump curve

Pressure Absorbed by 2-way Valves

71

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%0

50

100

150

200

250

HP

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Variable Speed/Variable Volume

Constant Speed/Variable Volume

Constant Speed/Constant Volume

Percent Operating Time

Graphical AOC Cost Comparison

72

Primary-secondary Pumping

Return

Supply

PumpController

Constant or Variable Speed Secondary Pumps


Chiller 3

Chiller 2

Chiller 1

Constant SpeedPrimary Pumps


73

How does P-S Work?Supply

C

H

I

L

L

E

R

C

H

I

L

L

E

R

C

H

I

L

L

E

R

Return

Primary-Secondary

Common

Primary Loop(Production )

Secondary Loop(Distribution )

74

Common Pipe DesignSupply

Primary Loop(Production)

Secondary Loop(Distribution)

Primary-secondary

Common

Chiller

3 Pipe Diameters, Minimum Length

Friction Loss < 1.5 ft

Return

EqualDiameter

Balance and Check Valve

75

Common Pipe Design

• Overall Pressure drop in the common pipe shall not exceed 1.5 ft.

• A distance of 3 pipe diameters between the common tees is desirable.

• The velocity of the secondary return should not exceed 5 fps.

76

How does P-S Work?

• Primary Flow = Secondary Flow

• Secondary Flow > Primary Flow

• Primary Flow > Secondary Flow

CHILLER

CHILLER

CHILLER

Return


SupplyPrimary Loop(Production)

Secondary Loop

(Distribution)

77

Front Loaded Common

Ch

iller 2

, off

Ch

iller 1

, on

78

Common -- No Flow

SecondaryPumps

1500

1500

1500 15000

CHWS Temp45oF

CHWR Temp55oF

ECW Temp55oF

1500

Ch

iller 2

, off

Ch

iller 1

, on

Production Flow = Distribution Flow

79

CHWS Temp

Common -- 500

SecondaryPumps

1500

2000

1500 20000

47.5oF

CHWR Temp55oF

ECW Temp55oF

Mixing (1500 @ 45) + (500 @ 55)

Ch

iller 2

, off

Ch

iller 1

, on

2000

Distribution > Production

80

Increasing Supply Water Temperature - How Serious?

• Coil Selection - additional rows.

• Series Chiller - for the critical load.

• Chiller Temperature Reset...– 1 to 3 % increase in operating cost per degree

of reset.

81

Common -- 900

SecondaryPumps

3000

2100

15002100

1500

CHWS Temp45oF

CHWR Temp55oF

ECW Temp52oF

Mixing (2100 @ 55) + (900 @ 45)

(Flow in GPM)

P/S Chiller Bridge - Front Loaded Common

Ch

iller1, on

Ch

iller 2

, on

Production > Distribution

82

StepFunction

LinearFunction

Return

Primary/SecondaryCommon

Supply

Production

Distribution

Ch

iller 3

Ch

iller 2

Ch

iller 1

Primary-Secondary Relationship

83

0-10 30-40 60-70 90-1000

5

10

15

20

25

30

0-10 30-40 60-70 90-100

% T

ime

% Load

Typical Load Profile

84

% Load

% Time

100

80

60

40

20

100755025

Chiller 1

Chiller 2

1

1 2 2

Ch

iller 2, 60%

Ch

iller 1, 40%

Applying a 60/40 Chiller Split

85

% Load

Time

Approaching Flow = Load

86

Chiller Sequencing

From Loads

Common Pipe

To LoadsProduction

SecondaryPumps

Distribution

Ch

iller 2

, off

Ch

iller 1

, on

FSTS-S

TS-R

Ch

iller 3

, off

Primary Pumps

TP-S

TP-R

FP

87

Back Loaded Common

SecondaryPumps

Ch

iller 2

, off

Ch

iller 1

, on

1500

88

Common0 Flow

SecondaryPumps

1500

CHWS Temp45oF

CHWR Temp55oF

Ch

iller 2

, off

Ch

iller 1

, on

1500

1500

15001500

Production = Distribution

89

Common500 gpm

SecondaryPumps1500

2000

1500 20000

CHWS Temp47.5oF

CHWR Temp55oF

500

Mixing (1500 @ 45) + (500 @ 55)

500

Ch

iller 1

, on

Ch

iller 2

, off

Distribution > Production

90

Common900

SecondaryPumps1500

2100

1500

2100

1500 GPM@ 49oF

CHWS Temp45oF

CHWR Temp55oF

Mixing (900 @ 45) + (600 @ 55)

900 600

900 GPM@ 45oF

600 GPM@ 55oF

1500 GPM@ 55oF

Ch

iller 2

, on

Ch

iller 1

, on

Production > Distribution

91% Load

% Flow

100755025

100

75

50

25

Ch 1Ch 2 Ch 3 Ch 4

Ch 1Ch 2 Ch 3

Ch 1Ch 2

Ch 1

Applying a Variable Speed Chiller

92

Hybrid Chiller Plant

Primary-SecondaryCommon

Return

Supply

SecondaryConstant Speed

Pumps

Ch

iller 3

Ch

iller 2

Ch

iller 1

93

Air Management

Air Removal

versus

Air Control

94

Types of Tanks

• Compression Tank

• Diaphragm

• Bladder

95

Compression Tank

System Connection

96

Diaphragm Tank

System Connection

Air Charge

97

Bladder TankSystem Connection

Air Charge

98

Standard Tank Installation

Tank

TankFitting

PRV

from system

to system Rolairtrol

LockShieldValve

Pitch up

PNPC

99

Diaphragm Tank InstallationSystem

Vent

Rolairtrol

FromSystem

Vent Diaphragm Tank

ThermalLoop

Lock ShieldValve

PNPC

To System

100

Standard or Diaphragm Tanks?

Standard• Water and air in contact• May be larger, heavier• Require tank fittings• Rarely require repair• Low initial cost

Diaphragm/Bladder• Impermeable barrier• Probably smaller• Require vents and

thermal loop• Repair difficult or

impossible• Higher initial cost

101

Pumping Away

Chiller 3

Chiller 2

Chiller 1


102

Tank LocationAir

Water

CompressionTank

Pump

System

Point of NoPressureChange

103

Pumping Away from the TankSystem Pressure

Pump Off

Pump On

PumpPressureDifference

PNPC

KeepShort

104

Pumping Toward the TankSystem

Pressure

Pump Off

Pump On

PumpPressureDifferencePNPC

105

Types of HVAC Pumping Systems

1. Primary-Secondary Pumped– Direct Return– Reverse Return

2. Primary-Secondary-Tertiary Pumped

3. Primary-Secondary-Tertiary Hybrid Pumped

4. Primary-Secondary Zone Pumped

5. Primary V/S Pumped

106

CHILLER

CHILLER

CHILLER

Return

Supply

PumpController

SecondaryPumps

1. Two Pipe Direct Return

107

Primary-Secondary PumpedAdvantages: Simplicity First Cost Efficient

Disadvantages: Over-pressurization Balancing Head requirement Thermally linked

108

1a. Two Pipe Reverse Return

CHILLER

CHILLER

Return

SecondaryPump

Supply Supply

Return

CommonPipe

PrimaryChillerPumps

Terminals Terminals Terminals

109

P-S with Reverse Return

Advantages: Simplicity Balancing First Cost

Disadvantages: Over-pressurization Head requirement Thermally linked Additional piping

110

Primary-secondary Variations

1. Primary-Secondary-Tertiary Pumped

2. Primary-Secondary-Tertiary Hybrid Pumped

3. Primary-Secondary Zone Pumped

4. Primary Variable Speed Pumped

111

2. Primary-Secondary-Tertiary

CHILLER

CHILLER

Zone A

Zone B

Zone C

Optional Variable Speed Pump

DP Sensor

ModulatingControl Valves

Secondary Pumps

CHILLER

Primary Pumps

Tertiary Pumps

Common Pipe

Common Pipe

112

Tertiary Zone

T3

T1

LoadMV

Load MV

Load MV

Common PipeT2

TertiaryZonePump

Tertiary BridgeSecondary Pump(s)

Secondary ChilledWater Return

Small BypassMaintains AccurateTemperature Reading

113

3-way valve application

Chiller P

lant

Secondary Pumps

TertiaryPump

TertiaryPump

TertiaryPump

114

T1

MV

CommonT2

T3

Load

Load MV

Load MV

T2T1 T3

FlowMeter

SmallBy-Pass

Secondary Supply

Secondary Return

Three-way Valve System

115

T2 T2T2 T2

FlowMeter

T3Common

T3CommonCommon

T3

Zone SupplyTemperature

Chiller SupplyTemperature

TerminalUnit Control

Valve

TerminalUnit Balance

Valve

ZoneBalanceValve

Zone BiasControl Valve

Rolairtrol

Zone(Tertiary)

Pump

ReturnWater

Temperature

Zone 3Zone 1 Zone 2 Zone 4

Common

3D Valves

Distribution(Secondary)

Pumps

T1T1 T1T1

T3

Chiller

Chiller

Chiller

GPX

Multi-zone application

116

District cooling application

• Individual building temperature control

• Static pressure isolation

• Return water temperature control

• Btuh Totalization

• Outdoor temperature reset

• Independent operation

117

District cooling application with GPX

• Independent pressure control

• Building operation isolation

• HVAC fluid isolation

118

Primary-Secondary-Tertiary

Advantages: Hydraulic isolation Thermal isolation Horsepower reduction Operational cost

savings System performance

optimization

Disadvantages: Additional piping Additional control

valves First cost Over-pressurization of

near zones More pumps

119

3. Primary-Secondary-Tertiary HybridZone C

CHILLER

CHILLER

PrimaryPumps

Secondary Pumps

Tertiary Pump

Zone A

Zone B

Supply

Return

Common Pipe

120

Primary-Secondary-Tertiary Hybrid

Advantages: Reduced first cost Horsepowerreduction Operational costsavings

Disadvantages: Insufficient pressure Additional control

valves First cost More pumps

121

Parallel Pump Curves

122

Variable Speed Pump Curve

123

Tertiary Pump Bypass Piping

TertiaryPump

SecondarySupply

SecondaryReturn

Common

Low PressureDrop Valve

N/C

N/C

N/O

124

CHILLER

CHILLER

Return

Supply

CommonPrimary

Secondary

ConstantSpeedChillerPumps

VSZonePump

CircuitSetter

VSZonePump

VSZonePump

4. Primary-Secondary Zone Pumping

125

Shared Piping

Return

Supply

Zone A Zone B Zone C

Shared Pipe

CHILLER

CHILLER

CHILLER

126

Primary-Secondary Zone Pumped

Advantages: Horsepower reduction Operational cost savings

Disadvantages: First cost Inflexibility More pumps Oversized pumps Control complexity Interlocked zones

127

Primary Variable Speed Pumping

AFD AFD AFD

CHILLER

CHILLER

CHILLER

FlowMeter

ModulatingControlValve

Two-position Control Valves

DP

Sensor

Controller

128

AFD AFD AFD

CHILLER

CHILLER

CHILLER

Flow Meter, option

ModulatingValve

Two-position Control Valves

DP S

ensor

Controller

DP

Sen

sor D

P S

ensorDP

Sen

sor


129

Design Considerations

• Size Bypass for Minimum Flow of Largest Chiller.

• Size Bypass Modulating Valve for Zone P.

• Size Chiller P Sensor for Minimum Chiller Flow.

• Sequence Chillers Based on P Switch or Temperature.

130

Consider this design if:• System flow can be reduced by 30%.

• System can tolerate modest change in water temperature.

• Operators are well trained.

• Demonstrates a greater cost savings.

• High % of hours is at:

– Part load.

– Full load with low entering condenser water.

131

Do not use if:• Supply temperature is critical.

• Constant volume.

• Existing controls are old or inaccurate.

• Operator unlikely to operate as designed.

• System is noise sensitive.

132

Primary Variable Speed Cautions• System Volume• Rate of Change• Turn-down Ratio• Chiller Selection• Pump Selection• Supply Water Temperature• Controls Complexity• Sensor Calibration • Operator Ability

133

System Volume• Dictates impact of rate of flow change.

• Chiller protection.– Freeze up.– Trip out.

134

Rate of Change• Trane:

– 30% per minute flow change.– 10% per minute flow change.

• York: STR = System Volume Design Flow– If greater that 15, 100% to 50% in 15 minutes.– If less than 15, 100% to 50% in 15 + (15 - STR)

minutes.

135

Turn-down Ratio• Chiller manufacturers publish 3 - 11 fps

flow range.

• Nominal base of 7 fps desirable.

• Variation of 1 to 2 fps.

• Type and brand.

136

Chiller Selection• Equal size chillers.

– Redundancy.– Parts.– Maintenance.

• Unequal size chillers.– Control issues.– Flow issues– Additional equipment.

137

Pump Selection• Equal size pumps.

– Redundancy.– Parts.– Maintenance.

• Unequal size pumps.– Control issues.– Flow issues.– Premature failure.

138

Supply Water Temperature• Dependant on :

– System volume.– Rate of flow change.

• Application specific.

139

Controls Complexity• Additional controls for the chillers

• Additional controls the pumps.

• Pumps operate on flow, temperature, and P.

• Chiller P.

140

Sensor Calibration• Multi-sensor control:

– Flow.– Temperature. P.

• Maintenance.

• Calibration.

141

Operator Ability• Within operators ability?.

• Training is mandatory.– Initial– Periodic.

• Systems too complex?

142

Problems in the Field

• Difficulty in system control.

• Chiller stability.

• Laminar flow - heat transfer issues.

• Flow confirmation.

• Real world.

143

Advantages: Retrofits First cost Less pumps Single chiller systems Operational cost savings Floor space

Disadvantages: Retrofits First cost Big pumps & AFDs Inflexibility Control complexity Operation complexity Temperature variation Interlocked zones Turndown capacity


144

Sensor Location and Pump Sequencing

145

Return

Supply

PumpController

AFDs

DifferentialPressureSensorC

hiller 3

Chiller 2

Chiller 1

Sensor Location

146

Return

Supply

Variable Head Loss

Constant Head Loss

PumpController

AFDs

DifferentialPressureSensorC

hiller 3

Chiller 2

Chiller 1

Maximizing Variable Head Loss

147

CHILLER

CHILLER

CHILLER

PumpController

DP Sensors

Zone 1 Zone 2

AFDs

A B C D

EF

Control Area Example

148

P AB+EF 20FT

P Zone 1 20FT

P BC+DE 20FT

P Zone 2 20FT

TDH = P AB + EF + BC + DE + P ZONE 2 = 60 FT

Pressure Drops in Piping (Table 11-1)

149

Table 11-2 Control Area CalculationFlow, Zone 1 Flow, Zone 2 P AB+EF P Zone 1 P BC+DE P Zone 2 TDH

0 gpm 600 gpm 5 0 20 20 45300 gpm 300 gpm 5 10 5 20 30600 gpm 0 gpm 5 20 0 20 25 0 gpm 0 gpm 0 0 0 20 20600 gpm 600 gpm 20 40 20 20 60

Control Area Calculation

150

0

10

20

30

40

50

60

0 100 300 500 600 900 1100 1200Flow, gpm

Head

, FT

Lower Limit

Upper Limit

Single Point

Control Area Curve

151

Return

CHILLER

CHILLER

CHILLER

Supply

PumpController

DP Sensors

Zone A Zone B Zone C

AFDs

Applying Multiple Sensors

152

Return

Supply

PumpControllerAFDs

Chiller 3

Chiller 2

Chiller 1

WRONG!SinglePointPressure Sensor

Single Point Pressure Sensor

153H

ead, F

T

90

80

50

40

30

20

10

70

60

0200 400 600 800 1000 1200 1400 16000

Flow, gpm

1750 RPM (Maximum rpm)

1480 RPM(Minimum rpm)

Constant Pressure

Design PointShut-off head

Single Point Pressure Sensor

154

Staging Variable Speed Pumps in Parallel

1. Pump Speed

2. End-of-Curve Protection

3. Efficiency Optimization

155

Staging Based on Pump Speed

A lag pump is staged on after the lead pump in reaches full speed. The pumps then operate in parallel, varying their speed together. As load decreases, the lag pump is destaged and the lead pump maintains setpoint once again.

Required transmitter(s): Zone differential pressure only.

157

End of Curve Protection As the lead pump increases in speed, there may be

a point prior to reaching full speed where the single pump could operate off its published end of curve. Rather than allow this to occur, the lag pump is staged on so as to share the flow requirements.

Required transmitter(s): Zone differential pressure and a flow meter.

159

System Efficiency OptimizationAs the speed of the lead pump increases in relation to load, the overall efficiency of the pumping system (pump, motor, drive) also changes. For any given system there may be a range in speed where it is more efficient to run multiple pumps in parallel even though one pump could satisfy the load without end of curve concerns.

Required transmitters: Zone differential pressure, flow meter, kilowatt meter, and system differential pressure transmitter.

1 pumping system fundamentals 2014 jeff turner systecore inc

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