fluid system 06-pump system

8/11/2019 Fluid System 06-Pump System

http://slidepdf.com/reader/full/fluid-system-06-pump-system 1/17

Prof. Dr. Ir. Harinaldi, M.EngMechanical Engineering Department

Faculty of Engineering University of Indonesia

Pump system



Pump and System Matching

2 KQ H h H H sloss s

System CurveStatic Head:

12 z z H s Head loss = friction + minor losses

g kV gd flV h iiii 224 22

g kV gd flV h oooo 224 22

At inlet:

At outlet:

From pipe flow :

2

2

ResistanceSystem KQ

Qhhh oiloss

System Curve/System Equation :

parabolic



Pump Performance CurvePump and System Matching

Pump performance curves are obtained from a pump testing by themanufacturer and provided as pump documentation



System Matching and Pump Selection

Pump Selection:- use system and pumpperformance curves

- operating condition isthe intersection pointof the curves

- operating conditionshould be designed toreach the bestefficiency point (BEP)




Non DimensionalParameter

P gQH

Efficiency

D N P

P Coef Power ND

QCoef Flow

D N gH Coef Head

.

.

.

53

3

22

P

:Therefore



For the Best Design Point (Maximum Efficiency)

DimensionlessSpecific Speed

Non Dimensional Parameter

22

3

D N gH NDQ

D

D

Eliminating D in two eq.

2/3

2

2/3

2/32

gH

Q N gH Q N

D

D

D D

(rad) 4/3

2/1

4/3

2/1

gH

NQ N

D

D s



Pump Scaling LawTo predict the characteristics of operation for pumps which aregeom etr ica l ly s im i lar

2

22

1

1121

52

32

25

13

1

121

22

22

22

12

1

121

P

H gQ

P

H gQ

D N P

D N P

P P

D N gH

D N gH

For two

pumps whicharegeometricallysimilar andoperate withthe same flow

coefficient

322

2311

1

21

D N Q

D N Q

Pump Scaling Law



Pump Affinity Law 1Effect of Speed Variation

- How pump characteristics is affected by changing operating speed N of agiven pump with the same flow coefficient

32

23

1

1

22

22

1

1

2

2

1

1

2121

;

N P

N P

N H

N H

N

Q

N

Q

N N D D

2

Q H



Pump Affinity Law 1Effect of Speed Variation

In case of system resistance with certain static head



Pump Affinity Law 2Effect of Pump Diameter Variation

- How pump characteristics is affected by varying pump diameter Doperating at a given constant speed with the same flow coefficient

52

25

1

1

22

22

1

1

3

2

23

1

1

2121

;

D P

D P

D H

D H

D

Q

D

Q

N N D D

3/2Q H

Note :The effects of viscosity and surfaceroughness can not be neglected if the

pump size decreases. Theseeffects more significantly influenceefficiency because of smaller clearancesand blade size.

An approximate, empirical relationship toestimate the influence of diminishing sizeon efficiency is:

1/ 5

2 1

1 2

1

1

D

D



Pumps Arrangements

Series Parallel

Basic Arrangement



Pumps ArrangementsTwo Similar Pumps in Series

to increase headperformance curve :adding heads at thesame flow ratefor two identicalpumps, the actualhead gained by thefluid and the flowrate are increased,but neither will bedoubled if thesystem curveremains the same.



Pumps in Series and Parallel

to increase flowrate/capacityperformance curve:adding flow rates atthe same head

for two identicalpumps, the flowrate for the systemwill not be doubledif the same systemcurve applies.

Two Similar Pumps in Parallel



Pumps in Series and ParallelArrangement of Non Similar Pumps



Axial Pumps in Parallel

Single axial pump Axial pumps in parallel



Sebuah pompa sentrifugal, mempunyai diameter sudu jalan d = 50 cm, kapasitas, Q = 3,2 m 3/s. tinggi tekan

(head),H=25m, putaran poros (n) = 1450 rpm.

• Jika efisiensi pompa 82%, berapa BHP (Brake HorsePower) nya dari poros, agar pompa dapat bekerja ?

• Jika sebuah pompa sentrifugal lain namun dalam satukeluarga (homologous) dengan efisiensi 82 %, berapakapasitas (Q), tinggi tekan (H) dan BHP-nya? d = 80cm, n = 1200 rpm

• Hitung putaran spesifiknya (n s)

fluid system 06-pump system

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