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© 2007 ASHRAE Hong Kong Chapter Slide 1
Fundamentals of Water System Design
17, 18, 24, 25 January 2007
ASHRAE Hong Kong Chapter Technical Workshop
© 2007 ASHRAE Hong Kong Chapter Slide 2
Chapter 8:Matching Pumps to Systems
1. Matching the Pump to the System2. Parallel Pumping3. Series Pumping4. Standby Pumps 5. Trimming Pump Impellers6. Two-speed Pumping7. Variable-speed Pumping8. Source Distribution Pumping
© 2007 ASHRAE Hong Kong Chapter Slide 3
Typical System Curve
© 2007 ASHRAE Hong Kong Chapter Slide 4
Pump Curve and System Curve
© 2007 ASHRAE Hong Kong Chapter Slide 5
Shift of System Curve
© 2007 ASHRAE Hong Kong Chapter Slide 6
Pump Curve for Parallel Operation
© 2007 ASHRAE Hong Kong Chapter Slide 7
Operating Conditions forParallel Pump Installation
© 2007 ASHRAE Hong Kong Chapter Slide 8
Piping Schematic of Parallel Pumps
© 2007 ASHRAE Hong Kong Chapter Slide 9
Pump Curve for Series Operation
© 2007 ASHRAE Hong Kong Chapter Slide 10
Operating Conditions for Series Pump
© 2007 ASHRAE Hong Kong Chapter Slide 11
Piping Schematic of Series Pumps
© 2007 ASHRAE Hong Kong Chapter Slide 12
Standby Pump
© 2007 ASHRAE Hong Kong Chapter Slide 13
Pump Affinity Laws
Speed Change Impeller Diameter Change
Flow:
Pressure:
Power:
⎟⎟⎠
⎞⎜⎜⎝
⎛=
1
212 N
NQQ ⎟⎟⎠
⎞⎜⎜⎝
⎛=
1
212 D
DQQ
2
1
212 ⎟⎟
⎠
⎞⎜⎜⎝
⎛=
NNpp
2
1
212 ⎟⎟
⎠
⎞⎜⎜⎝
⎛=
DDpp
3
1
212 ⎟⎟
⎠
⎞⎜⎜⎝
⎛=
NNPP
3
1
212 ⎟⎟
⎠
⎞⎜⎜⎝
⎛=
DDPP
© 2007 ASHRAE Hong Kong Chapter Slide 14
Pump Operating Points
© 2007 ASHRAE Hong Kong Chapter Slide 15
Two-Speed Pumping
© 2007 ASHRAE Hong Kong Chapter Slide 16
Typical Impeller Performance Curve
© 2007 ASHRAE Hong Kong Chapter Slide 17
Two-Speed Pumping Example
% ChangeFlow Power
46 1658 2778 57100 100
© 2007 ASHRAE Hong Kong Chapter Slide 18
Typical Direct Return System
© 2007 ASHRAE Hong Kong Chapter Slide 19
Pressure Loss With Two-Way Valves
© 2007 ASHRAE Hong Kong Chapter Slide 20
Proportional Controller and AFD
© 2007 ASHRAE Hong Kong Chapter Slide 21
Measuring Δp in Direct Return System
End of last riser, or highest
pressure drop
© 2007 ASHRAE Hong Kong Chapter Slide 22
Differential Pressure Control Curve Above Piping Friction Loss
© 2007 ASHRAE Hong Kong Chapter Slide 23
Measuring Δp in Reverse Return System
Central or typical zone
© 2007 ASHRAE Hong Kong Chapter Slide 24
Pressure Reduction WithChange in Pump Speed
25%
© 2007 ASHRAE Hong Kong Chapter Slide 25
Pumping Power ReductionWith Change in Pump Speed
12.5%
© 2007 ASHRAE Hong Kong Chapter Slide 26
Primary-SecondaryPumping Concept
(decoupler)
constant flow variable flow
© 2007 ASHRAE Hong Kong Chapter Slide 27
Primary-SecondaryVariable Speed Pumping
© 2007 ASHRAE Hong Kong Chapter Slide 28
Distributed Variable Speed Pumping