Structural Engineering Centrifugal Pump Test Laboratory Engineering Essay

This study examines the centrifugal pump. First by analyzing the system caput feature, so by analyzing the effects changing the motor velocity has on a individual pump. Finally the study examines and compares the usage of two pumps in series and so in analogue.

Theoretically scrutiny of the system head feature should give a graph of system caput against volume flowrate which is curved, the curve should get down above nothing from the Y axis, due to inactive lift.

Theoretically scrutiny of the consequence of changing motor velocity across a system of a individual pump should demo that higher motor velocities lead to higher efficiency in the pump system along with larger alterations of power across the system, and a larger bead in caput values.

Finally comparing of a system with two pumps used in series and in analogue should demo that the method used will non hold an consequence on the efficiency of the system. However it should besides demo that the system in series has twice the caput values of that in analogue and that the system in analogue has twice the volume flowrate values of the system in series. Overall they should hold the same Mass flow.

Upon comparing of the consequences obtained with theory, it is apparent that for the most portion, the experimental consequences agree with theory. Any minor dissensions between theory and experimentation will be explained in the treatments and decisions subdivision of this study.

This study serves to expose cognition and apprehension of the operation of a centrifugal pump gained from completion of the experiment.

Introduction

The intent of this research lab is to analyze the operation and public presentation of a centrifugal pump. Centrifugal pumps are an illustration of a unstable machine. Fluid machines are devices that transfer energy to or from a fluid. Fluid machines include pumps, fans and compressors. This experiment trades with a pump.

Pumps are devices used to travel gases or liquids from lower to higher force per unit area. The difference in force per unit area is overcome by adding energy to the system. Specifically, centrifugal pumps operate by change overing rotational kinetic energy into hydro dynamic energy. The rotational energy is typically supplied by an engine or electric motor or turbine.

Centrifugal Pumps are an of import machine to analyze from an technology point of position as they are really widely used as a agency of presenting liquids. Centrifugal pumps are used in Fieldss such as sewerage, crude oil and petrochemical pumping.

For the intent of this study the centrifugal pump was studied in footings of its public presentation when a individual pump was used and besides when two pumps were used ( both in series and in analogue ) . The intent being to foreground the effects this had on consequences. The system feature was besides investigated. The overall intent of this experiment is to give a better apprehension and penetration into how this fluid machine works. Below is an image of a centrifugal pump. A greater penetration into how it operates and an account of the map of the assorted parts will be provided subsequently in the study.

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Figure 1 – Centrifugal Pump Diagram 1

Aims

The primary purpose of this research lab is to derive a better apprehension of pumps, in peculiar the centrifugal pump. Insight is gained into the rules of operation of a centrifugal pump and the procedure through which a pump transportations energy to a fluid system.

There are three parts to this experiment:

To find the system characteristic for the fluid system on which the pump operates.

To find the public presentation of a individual pump relation to drive velocity.

To find ( for a fixed motor velocity ) the public presentation of two centrifugal pumps ;

Operating in series ( two ) Operating in analogue

Theory

Basic theory and workings of Centrifugal pump

As antecedently stated, the rule operation of a centrifugal pumpA is to change over unstable speed into force per unit area energy.A The pump is made up of three constituents ; the recess canal, theA impeller, and the spiral.

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Figure 2: Centrifugal Pump Diagram 2

Fluid enters the recess canal ( D ) .A As the shaft ( A ) rotates, the impeller ( B ) , which is connected to the shaft, alsoA rotates.A The impeller consistsA of a figure of bladesA thatA undertaking the fluid outward when rotating.A This centrifugal force gives the fluid a high velocity.A Next, the traveling fluid passesA through the pump instance ( C ) A and so into the spiral ( E ) .A The spiral chamberA has a uniformly increasing area.A This increasingA country decreases the fluidsA speed, which converts theA speed energy into force per unit area energy. 2

Determining the System Characteristic

The first measure of the experiment is to place the system feature of the pump.

When a pump is fitted in a system, it is tested so as to guarantee that the volume flow-rate and caput of the pump are within needed specifications. The Volume flow rate can be defined as the volume of the fluid that passes through a given surface per unit clip, and the caput of the pump is a step of the fluid energy.

In order to make this we must happen the pump caput and the volume flow rate. We so plot the pump caput ( expressed in meters ) against the volume flow rate ( expressed in m3/s ) . This should give a curve.

The system caput feature is dependent on inactive lift which is associated with alteration in lift of the fluid, contraction or enlargement of the fluid associated with acceleration and slowing of the fluid, and the losingss within the system. Below is a theoretical graph, demoing how the curve should look.

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Example graph for system caput characteristic3

When a pump is attached to a system the ‘operating point ‘ occurs when the pump caput hpump equals the system caput hsystem. The optimal operating conditions occur when the needed ‘duty point ‘ of caput and flow intersects the ‘operating point ‘ and the ‘design point ‘ , the point of maximal efficiency.

Single Centrifugal Pump Characteristics

The following facet of the experiment is to find the public presentation of a individual pump as a map of motor velocity. The public presentation of a pump is by and large mapped by plotting pump caput ( hpump ) , electrical power ( Pelectrical ) and pump efficiency ( I·pump ) as a map of the volume flow rate Q through the pump.

The usage of a individual pump is investigated for three different motor velocities, mensurating the consequence changing the motor velocity has on pump caput, electrical power and efficiency. These values are so plotted on a graph against the volume flow rate.

Theoretically ;

Higher velocities yield higher efficiency

Higher motor velocities lead to a larger alteration in power across the system.

Higher motor velocities yield higher caput values ( expressed in meters ) .

Double Centrifugal Pump Characteristics

The concluding facet of this experiment is the probe of the effects of the usage of two centrifugal pumps on the system. The pumps are placed in series and so in analogue. Both systems, i.e. the pump system which is in series and that which is in analogues are set to the same motor velocity. In both instances head, electrical power and efficiency are measured and plotted against volume flow rate. The graph for the system in series can so be compared to the graph for the system in analogue, in order to analyze and compare the different systems.

Centrifugal pumps both in series are used to get the better of larger system caput loss than one pump can manage entirely, whereas centrifugal pumps in analogue are used to get the better of larger volume flows than one pump can manage alone.4

When running in series, the caputs are added and the entire capacity is equal to that of the pump with the smallest capacity, whereas in analogue, the capacities of the pumps are added, and the caput of all pumps will be equal at the point where the dismissed liquids recombine.5

Theoretically whether the system is in series or in analogues should n’t impact the efficiency of the system.

Experimental Methods

Equipment Used-

The primary piece of equipment used was the centrifugal pump, a elaborate account of its operation can be found in the theory subdivision of this study ( see page 6 ) .

We besides use a differential force per unit area transducer, which is a type of force per unit area detector.

We use a computing machine to mensurate and enter information.

Methods-

System Head Characteristic

Open valve V1 and near valve V2 located in the recess grapevines to pumps 1 and 2.

Close valve V3 which connects the mercantile establishment grapevine from pump 1 to the recess grapevine to pump 2

Open valve V4 located in the mercantile establishment grapevine from pump 1.

Open the discharge valve V5 to about 75 % of its to the full opened place.

Unplug the low force per unit area line linking differential force per unit area transducer to upstream of pump 1.

Record the motor velocity, the discharge volume flow rate, the force per unit area measured by the differential force per unit area transducer and the system caput.

Increase the velocity of motor 1 incrementally, at each increase repeat the above measure and go on to make so until the motor velocity had reached its upper limit.

Plot the system head characteristic against volume flow rate.

Single Pump

Open valve V1 and near valve V2 located in the recess grapevines to pumps 1 and 2.

Close valve V3 linking the mercantile establishment grapevine from pump 1 to the recess grapevine to pump 2

Open valve V4 located in the mercantile establishment grapevine from pump 1.

Close to the full the discharge valve V5.

Put the velocity of the motor connected to pump 1 utilizing the motor velocity accountant to 45 Hz

Record the Volume flowrate Q, the pump caput horsepower, the electrical power consumed Pelectrical and the pump efficiency I·pump.

Open valve V5 incrementally, at each increase reiterating the above measure and go oning until the valve is to the full opened.

Plot pump caput, electrical power and efficiency against volume flow rate Q at that motor velocity.

Repeat the process for motor velocities of 35 and 40Hz.

Double Pump

In Series

Open valve V1 and near valve V2 located in the recess grapevines to pumps 1 and 2.

Open valve V3 linking the mercantile establishment grapevine from pump 1 to the recess grapevine to pump 2.

Close valve V4 located in the mercantile establishment grapevine from pump 1.

Close to the full the discharge valve V5.

Put the velocity of the both motors connected to pump 1 & A ; 2 to 45 Hz utilizing the motor velocity accountant.

Record the volume flowrate Q, the pump caput horsepower, the electrical power consumed Pelectrical and the pump efficiency I·pump.

Open valve V5 incrementally, at each increase reiterating the above measure and go oning until the valve is to the full opened.

Plot pump caput, electrical power and efficiency against volume flow rate Q at that motor velocity.

In Parallel

Open valve V1 and near valve V2 located in the recess grapevines to pumps 1 and 2.

Open valve V3 linking the mercantile establishment grapevine from pump 1 to the recess grapevine to pump 2.

Close valve V4 located in the mercantile establishment grapevine from pump 1.

Close to the full the discharge valve V5.

Put the velocity of the both motors connected to pump 1 & A ; 2 to 45 Hz utilizing the motor velocity accountant.

Record the volume flowrate Q, the pump caput horsepower, the electrical power consumed Pelectrical and the pump efficiency I·pump.

Open valve V5 incrementally, at each increase reiterating the above measure and go oning until the valve is to the full opened.

Plot pump caput, electrical power and efficiency against volume flow rate Q at that motor velocity.

Experimental Consequences

System characteristic for the fluid system

Below is the tabular array of consequences for the finding of the system characteristic for the fluid system ;

Motor velocity N ( Hz )

Vol FlowrateQ ( m3/s )

a?†Psystem Pa

Hsystem ( m )

14

0

0.716

0.123333

21

0.188667

3.223

0.376667

25

0.368333

4.296667

0.486667

32

0.477667

6.911

0.753333

35

0.545667

8.450667

0.91

39

0.647667

10.06167

1.073333

42

0.714

12.71167

1.346667

47

0.796333

14.93167

1.573333

The graph for the system characteristic ( Hsystem against Volume flowrate ) is below:

Graph 1 ( System Characteristic )

Single Pump Test

Single Pump Test for Motor Speed 45 Hz-

Below is the tabular array of consequences for the individual pump trial at a motor velocity of 45Hz ;

Vol Flowrate Q ( m3/s )

Head ( m )

Efficiency %

Power W

0

8.786667

0

109.9433

0

8.443333

0

109.05

0

7.116667

0

116.8633

0

6.98

0

130.5333

0

7.306667

0

163.25

0.246333

7.32

9.7

181.8867

0.332667

7.186667

11.9

197.02

0.427333

7.016667

14.3

205.6467

0.537

6.833333

15.93333

226.0733

0.619667

6.38

16.53333

234.2133

0.738333

5.876667

17.1

249.1867

0.781333

5.703333

16.76667

260.4133

The corresponding graphs for the individual pump trial at motor velocity 45Hz are below ;

Entire Motor

Power ( W )

Single Pump Test for Motor Speed 40Hz-

Below is the tabular array of consequences for the individual pump trial at a motor velocity of 40 Hz ;

Vol Flowrate Q ( m3/s )

Head ( m )

Efficiency %

Power W

0

6.251868

0

128.0131

0.376333

5.406667

10.96667

178.8733

0.55

5.19

13.4

208.5767

0.675

4.706667

13.7

226.7267

0.7335

4.525

13.7

237.915

The corresponding graphs for the individual pump trial at motor velocity 40Hz are below ;

Entire Motor

Power ( W )

Single Pump Test for Motor Speed 35 Hz-

Below is the tabular array of consequences for the individual pump trial at a motor velocity of 35 Hz ;

Vol Flowrate Q ( m3/s )

Head ( m )

Efficiency %

Power W

0.054

4.722434

1.633333

118.0014

0.305667

4.276667

7.066667

170.9

0.592

3.65

9.666667

218.18

0.632333

3.546667

9.666667

226.3167

0.630333

3.343333

9.166667

225.1767

The corresponding graphs for the individual pump trial at motor velocity 35Hz are below ;

Entire Motor Power ( W )

Double Pump Test

System in series-

Below are the consequences of the dual pump trial for a system in series-

Vol Flowrate Q ( m3/s )

Head ( m )

Efficiency %

Power Motor 1 ( W

Power Motor 2 ( W )

Entire Motor Power ( W )

0

18.21333

0

109.2933

55.99

165.2833

0

15.38

0

128.4167

54.69

183.1067

0.255667

14.80333

15.16667

181.3167

62.82667

244.1433

0.43

14.38667

23.5

201.0067

57.37

258.3767

0.537667

13.70667

26.7

218.67

51.43

270.1

0.618667

13.08

26.86667

240.3967

54.44333

294.84

0.730333

11.65

26.96667

256.1867

52.89667

309.0833

0.852667

9.826667

25.06667

272.6233

54.68667

327.31

0.883333

9.863333

25.16667

278.16

60.62667

338.7867

The corresponding graphs for the dual pump trial for a system in series are below ;

Entire Motor Speed ( W )

System in parallel-

Below is the tabular array of consequences for the dual pump trial for a system in analogue ;

Volume Flowrate Q ( m3/s )

Head ( m )

Efficiency ( % )

Motor Power 1 ( W )

Motor Power 2

( W )

Entire Motor Power ( W )

0

9.19667

0

111.327

63.8833

175.21

0.277

7.6

11

134.847

52.49

187.3367

0.47167

7.67

17.3

144.773

60.1367

204.91

0.598

7.41667

20.1333

152.917

62.7467

215.6634

0.72033

7.33667

22.8333

165.443

61.28

226.7233

0.83633

7.39667

27

171.06

53.3867

224.4467

0.97033

7.11667

27.7

191.243

52.7333

243.9766

1.11633

6.85

28.3667

201.337

62.7433

264.08

1.29767

6.70667

31.9667

210.613

56.2367

266.85

1.37667

6.33

29.9667

228.597

55.6633

284.26

1.554

6.02667

30.9

241.21

59.4867

300.6967

1.63033

5.73

30

244.14

60.7933

304.9333

The corresponding graphs for the dual pump trial for a system in analogues are below ;

Entire Motor Power ( W )

Discussion & A ; Decisions

This subdivision of the study contains a treatment of the consequences obtained along with decisions drawn from said consequences and besides where necessary, remarks sing any unexpected values.

System Head Characteristic

The first portion of the experiment was conducted in order to achieve a system caput characteristic curve. Volume flowrate, measured in m3/s, was mapped against Head, which is measured in meters. We would anticipate this to give a smooth curve get downing above the zero grade organize the y- axis, in order to let for inactive lift in the pump system.

As expected the system head characteristic was found to be a curve, get downing somewhat above the zero grade on the Y axis, hence for the most portion, consequences were conclusive with theory. However there is one disagreement between expected consequences and the existent consequences obtained, as the curve is non wholly smooth.

Some possible grounds for the somewhat irregular form of the curve are ;

Single Pump Test

The 2nd portion of this experiment was to look into the consequence altering motor velocity has on a pump. In order to carry on this probe pump caput ( hpump ) , electrical power ( Pelectrical ) , pump efficiency ( I·pump ) and volume flowrate ( Q ) were measured for a assortment of motor velocities. Then hpump, Pelectrical and I·pump were mapped against Q for each motor velocity. The ground for this being to foreground the effects altering motor velocity has on the centrifugal pump system. We expect foremost that higher motor velocities yield higher efficiency, secondly that higher motor velocities lead to a larger alteration in power across the system and eventually that higher motor velocities yield higher caput values.

Upon analyzing the consequences of the experiment we can see that they match up with theory.

Efficiency-

Theory- Efficiency, merely put, refers to how good a pump can change over one signifier of energy into another. In this instance how good the pump converts rotational kinetic energy into hydrodynamic energy. The overall efficiency of a centrifugal pump is defined as the ratio of the H2O ( end product ) power to the shaft ( input ) power. By increasing the velocity at which the motor rotates the shaft, the shafts power is increased, hence the value of efficiency is increased.

Results- Higher motor velocities did in the instance of this experiment did give higher values for efficiency. For a motor velocity of 45 Hz the highest efficiency value obtained was about 16.7 % , for a motor velocity of 40Hz Hz the highest efficiency value obtained was about 13.7 % and eventually for the lowest motor velocity used, 35Hz, highest efficiency was about 9.16 % .

Power Change-

Theory- Power can be defined as a work/time ratio. The work in the instance of this experiment is the rotary motion of the shaft by the motor, which in bend creates a centrifugal force in the H2O. For a faster motor velocity, the shaft rotates faster, intending that more work is done per unit clip. This means a greater rise in the power value.

Results- In this experiment, as expected, higher motor velocities yielded larger alterations in power across the system. For a motor velocity of 45 Hz the rise in power in across the system was about 150.47 Wattss. For a motor velocity of 40 Hz the rise in power in across the system was about 109.9 Wattss. Finally, for the lowest motor velocity used, 35 Hz, the alteration in power in across the system was about 107.18 Wattss.

Head-

Theory- Head is the tallness at which a pump can raise H2O up. The higher the value of force per unit area, the higher the value of caput will be. Since raising rotational velocity strongly affects pressure loss of a fluid, we can see that it besides affects head loss. A

Results- In this experiment, as expected, higher motor velocities lead to a greater loss in caput ( measured in meters ) across the system. For a motor velocity of 45 Hz the bead in caput across the system was about 3.09 meters. For a motor velocity of 40 Hz bead in caput across the system was about 1.727 meters. Finally, for the lowest motor velocity used, 35 Hz, bead in caput across the system was about 1.38 meters.

Double Pump Test

The concluding portion of the experiment was to look into ( for a fixed motor velocity ) ; the

public presentation of two centrifugal pumps ; foremost runing in series and secondly runing in analogue. The two consequences for the system in series and for the system in analogue could so be compared. In order to carry on this probe pump caput ( hpump ) , electrical power ( Pelectrical ) , pump efficiency ( I·pump ) and volume flowrate ( Q ) were measured, foremost for the system in series and secondly for the system in analogue.

Theoretically, when both systems are set at the same motor velocity, the pump in series should hold twice the Head value of the system in analogue, whereas the system in analogue should hold twice the volume flowrate of the system in series. Meaning that both systems end up with the same mass flow. Whether the pumps are in series or in analogue should hold no consequence on the efficiency of the system.

Head-

Theory-

Results- As expected the system in series has about twice the caput value of the system in analogue. ( Series18.22m: Parallel 9.2m )

Volume Flowrate-

Theory-

Results- As expected the system in analogue has about twice the volume flowrate value of the system in series. ( Series 0.883: Parallel 1.63 )

Mass Flow-

Theory-

Results-

Efficiency-

Theory-

Results-