290840829-Flowmeter-Demonstration-Lab-Report.docx

Thermofluid lab: Flowmeter demonstration

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UNIVERSITI TEKNOLOGI MARA FAKULTI KEJURUTERAAN KIMIA THERMOFLUID LAB (CGE 536) EXPERIMENT DATE PERFORMED SEMESTER PROGRAMME/CODE GROUP

: FLOWMETER DEMONSTRATION : 29/9/2015 :3 : THERMOFLUID LAB / CGE 536 : EH2433B

NAMA MUHAMMAD EZWAN BIN MOHD HANAFIAH NUR AMANINA BINTI AHMAD NIZAMUDDIN

NO PELAJAR 2014620734 2014260632

MUHAMMAD IKHMAL BIN YAHYA

NO. 1 2 3 4 5 6 7 8 9 10 11 12 13

2014418774

TITLE

ALLOCATED MARKS MARKS % 5 5 5 5 5 10 10 10 20 10 5 5 5 100

ABSTRACT/SUMMARY INTRODUCTION AIMS/OBJECTIVES THEORY APPARATUS PROCEDURES RESULT CALCULATIONS DISCUSSION CONCLUSIONS RECOMMENDATIONS REFERENCES APPENDICES TOTAL

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Remarks : Checked by: CONTENT

PAGE

SUMMARY INTRODUCTION OBJECTIVES THEORY APPARATUS/MATERIALS PROCEDURE RESULT CALCULATION DISCUSSION CONCLUSION RECOMMENDATION/REFERENCE APPENDICES TABLE OF CONTENTS:

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3 4-6 7 8-10 11 12 13 14-17 18 19 20 21-24


SUMMARY:

EXPERIMENT 1: Demonstration of the operation and characteristic of three different basic types of flowmeter

The experiment has been done to measure the flow rate and pressure loses using three basic types of flow measuring techniques; rotameter, venturimeter and orifice meter. After all apparatus have been set up, we must measure the time taken of a known volume of water (3 litres) to accumulate in the water tank to calculate the flow rate. Next, we have to record the manometer reading (A-J) and the flow rate reading in different techniques. To get accurate reading, we must repeat the experiment 3 times. EXPERIMENT 2: Determination of the loss coefficient when fluid flows through a 90 degree elbow

The experiment has been done to determine the loss coeffient when fluid flows through a 90 degree elbow. After all apparatus have been set up, the flow rate have been taken by measure the time of a known volume of water to accumulate in a tank. The reading in manometer I and J is record. At the end of

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experiment, a graph of ∆H against

V 2s 2g

for 90 degree elbow to determine the

coefficient of losses. To get accurate reading, we must repeat the experiment 3 times.

INTRODUCTION : EXPERIMENT 1: Fluid mechanics is the branch of physics that studies the behaviour of fluid especially liquid in many form of application which is statics, dynamics and thermodynamics. In order to study this behaviour of fluids, we need a device known as flowmeter. Flowmeter is a device used to measure the flow rate or a quantity of fluids flow through a pipe. The hydraulic bench (Model: FM 110) is provided in the laboratory and were connected to the flowmeter measurement apparatus (Model: FM 101) which consists of venturi meter, orifice meter and rotameter.

Venturi meter Venture meter is a tube consists of three parts which is a short converging part, throat and diverging part. Inside the venture meter, pressure difference is 4

Thermofluid lab: Flowmeter demonstration created by reducing the cross sectional area of the flowing path. The pressure difference is measured using the manometer. The pressure difference is useful to calculate the flow rate of fluid through the pipe line. The inlet area of the venturi is larger than the throat causing the velocity at the throat increases due to the pressure decreases. As the conclusion, a pressure difference is created between the inlet and the throat of the venturi. To understand the principle of venture meter, we must know the Bernoulli’s equation.

Orifice meter An orifice meter is generally a thin orifice plate with a hole in the middle. It is placed in a pipe which a fluid flows. As the fluid reaches the orifice plate, the fluid is forced to flow through the hole in the middle of the orifice plate. Vena contracta which is the point of maximum convergence is produced downstream of physical orifice. As this occurs, the velocity and the pressure will change. At the vena contracta, the velocity and pressure change once again due to the fluid expand. The flow rates can be obtained from Bernoulli’s equation by measuring the pressure difference between normal pipe section and the vena contracta.

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Rotameter. Rotameter is a class of meters called as variable area meters. It consists of three basic elements that are a uniformly tapered flow tube, a float and a measurement scale. Rotameter is usually position vertically in the system with smallest diameter at the end of the tapered flow tube at the bottom which is the fluid inlet. When fluid flow through a float in tapered tube, pressure difference is created. As the float moves upwards, the fluid flowing area increases due to the decreasing of pressure difference.

EXPERIMENT 2: The value of the loss coefficient is very important to accurately calculate the flow rates and pressure drop in pipes. In long straight pipe, the pressure drop is due to the friction in the pipe which is also known as major losses. The pressure drop caused by fittings or valves is known as minor losses which will be calculated at the end of the experiment. As pipes get shorter and more complicated the proportion of losses due to fittings and valves gets larger, but by convention is also known as minor losses. The type of pipe fitting contain in this experiment is 90 degree elbow.

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OBJECTIVE : EXPERIMENT 1: 

To obtain the flow rate measurement by utilizing three basic types of flow measuring techniques; rotameter, venturi meter and orifice meter.

EXPERIMENT 2: 

To investigate the loss coefficient of fluid through 90 degree elbow.

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THEORY: EXPERIMENT 1: Bernoulli equation is applied to calculate the flow rate in both venturi meter and orifice: 1. By determine point 1 and 2 at the flowmeter:

2. By using continuity equation, we can eliminate velocity,u 2:

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3. Substituting this into and rearranging Bernoulli’s equation:

4. To get the actual result, coefficient discharge have to be consider in the calculation:

In this experiment, Z1=Z2. Therefore, Z1 and Z2can be cancelling out. A1 : Area at point 1 A2: Area at point 2 P1: Pressure at point 1 P2: Pressure at point 2 U1: Velocity at point 1 U2: Velocity at point 2 9


Values of discharge coefficient are determined by experimented, the assumed values used in the software are: CdVenturi meter= 0.98 Cd Orifice plate = 0.63 The head loss (h, metre) is recorded due to the height reading of manometer. In this experiment, the head losseswill be compared with the flow rate used. Pressure loss for venture meter is low while for the orifice the pressure loss is medium.

EXPERIMENT 2: To calculate the loss coefficient, the equation use is: 2

HL = K x

V 2g

Where, HL= Head Loss K= Loss Coefficient V= flow velocity g= Acceleration of gravity

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Thermofluid lab: Flowmeter demonstration The usual value use for g is 9.81N.

APPARATUS:

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PROCEDURE: EXPERIMENT 1: 1. Apparatus was placed on the bench, inlet pipe connected to bench supply and outlet pipe into volumetric tank. 2. With the bench valve fully closed and the discharge valve fully opened, the pump supply and the hydraulic bench was started up. 12

Thermofluid lab: Flowmeter demonstration 3. The bench valve was slowly opened until it is fully opened. 4. When the flow in the pipe is steady and there is no trapped bubble, bench valve is started to close in order to reduced the flow to the maximum measurable flowrate. 5. By using the air bleed screw, water lvl in the manometer was adjusted. maximum reading of manometer was retained with the maximum measurable flowrate. 6. Reading on manometer(A-J), Rotormeter and maximum measureable flowrate was noted. 7. Step 6 is repeated for different flow rates. The flow rates can be adjusted by utilizing both bench valve and discharge valve.

EXPERIMENT 2: 1. Repeat step (1-6) from experiment 1. 2. Complete the data table. 2

Vs 2g 3. Graph of H against

for 90 degree elbow was plotted to determined the

coefficient of losses.

RESULT Demonstration of the operation and characteristic of three different basic types of flowmeter

NO.

A

B

MANOMETER READING (MM) C D E F G 13

H

I

J

Thermofluid lab: Flowmeter demonstration 1 2 3 4 NO.

1

2

265 295 338 374

263 290 327 255

ROTA METER (L/MIN) 5

253 256 256 241

259 277 301 315

VOL (L)

TIME (MIN)

3

0.5155

10

3

261 282 312 333

252 287 322 349

FLOWRA TE Q(L/MIN) 5.82

0.2618

11.16

262 287 322 348

239 203 143 57

×10−4

×10−5

1.8623

1.7570

×10

4

15

3

20

3

0.2000

15.00

0.1363

21.53

248 235 210 166

FLOWRATE USING BERNOULLI EQ VENTURI ORIFICE 1.0330 9.1939

−4

3

249 238 215 170

×10

−4

2.7004

2.5648

×10−4

×10−4

3.4391

3.2702

−4

×10

×10

−4

Determination of the loss coefficient when fluid flows through a 90 degree elbow

No.

1

Volume

Time

(L)

(sec)

3

Flowrate, Q

Differential Piezometer Head, ∆h' (mm)

(l/min)

Elbow (hI-hJ)

3

4

3 3

(m/s)

(mm) 1.7087

1

0.183 1

16.13

×10−3 6.2790

3

0.351 0

15.00

5

0.471 8

0.01134

21.23

4

0.677 2

0.0233

11.16 3

V2/2g

30.93 5.82

2

V

12.00 8.36

14

×10−3


CALCULATION

EXPERIMENT 1 For the venturi meter Upstream pipe diameter

Cross sectional area

Throat diameter

∅1

= 26mm

A1

=

∅2

−4 = 5.3093 ×10 m2

= 16mm

Cross sectional area of throat

Discharge coefficient

π d2 4

A2

=

Cd ven

π d2 4

−4 = 2.0106 ×10 m2

=0.98

For the orifice plate Upstream pipe diameter

∅1

= 26 mm

Cross sectional area of upstream pipe A1

Throat diameter

∅2

−4

= 5.3093 ×10

m2

= 16mm

Cross sectional area of throat

Discharge coefficient

=

π d2 4

Cdorifice

A2

=

π d2 4

=0.63

15

−4

= 2.0106 ×10

m2


Timed Flow rate, Qt (m3/s) = V = Volume Collected t Timed to collect = 0.003 m3/ 30.93 = 9.70 x 10-5 m3/s Variable Area Flow Rate, Qa (m3/s) = Value from instrument reading (L/min) 60, 000 = 5 L / min 60, 000 = 8.33 x 10ˉ5 m3/s

Orifice Plate Flow Rate, Qo (m3/s)

=

Cd A2

(√ ) 2g ∆ H A2 2 1−( ) A1 0.016 ¿ ¿

=

π (¿ 2¿¿ 4)

(√

2(9.81)(0.023) 0.016 4 1−( ) 0.026 ¿ (0.63)¿

=9.1939 x 10ˉ5 m3/s

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)


Cd A2

Venturi Meter Flow Rate, Qv (m3/s) =

(√ ) 2g ∆ H A 2 1−( 2 ) A1

0.016 ¿ ¿ =

π (¿ 2¿¿ 4)

(√

2(9.81)(0.012) 0.016 4 1−( ) 0.026 ¿ (0.98)¿

)

= 1.0330 x 10-4 m3/s

Rotameter % Error

= (Qa – Qt) x 100 Qt = (8.3333 x 10ˉ5 − 9.70 x 10-5) x 100% 9.70 x 10-5 = -14.08%

Orifice Plate % Error

=

(Qo – Qt) x 100 Qt = (9.1939 x 10ˉ5 − 9.70 x 10-5) x 100% 9.70 x 10-5 = -5.21%

Venturi Meter % Error

=

(Qv – Qt) x 100 Qt = (1.0330 x 10-4 − 9.70 x 10-5) x 100% 9.70 x 10-5 = 6.49%

This calculation is repeated for the 2 , 3 ,4 repeated experiment to find accurate data Flow rate 17

Thermofluid lab: Flowmeter demonstration No

Time flow rate Qt (m3/s)

1 2 3 4

−5

9.699 ×10

Rotameter Flow Rate Qa (m3/s) 8.3333 −5

×10

1.8599 ×10

−4

2.5000 ×10

−4

3.5894 ×10

−4

1.6667

×10

−4

2.5000

×10

−4

3.3333

×10

−4

Venturi meter Flow rate Qv (m3/s)

Orifice Flow rate Q0 (m3/s)

1.0330 ×10

−4

9.1939 ×10

−5

1.8623 ×10

−4

1.7570 ×10

−4

2.7004 ×10

−4

2.5648 ×10

−4

3.4391 ×10

−4

3.2702 ×10

−4

Percentage error compare to time flowrate

No 1 2 3 4 average

Rotameter % flow rate error (%) -14.08 -10.39 0 -7.13 7.90

Orifice plate % flow rate error (%)

Venturi meter % flow -rate error (%)

6.50 0.13 8.02 -4.19 4.71

-5.21 -5.53 2.59 -8.89 5.56

Average is calculated by change negative value to positive to determine the accurate flowrate measurement .

EXPERIMENT 2 Theoritical value : Elbow flanged regular 90®= 0.3

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H 6 5 f(x) = 0.12x + 1.94

4

H Linear (H)

3

Linear (H)

2 1 0 0

5

10

15

20

25

The slope, K = 0.1228 % error =( 0.1228-0.3) x 100% 0.3 = 57.0%

DISCUSSIONS Objective of this experiment 1 is to obtain the flow rate measurement by utilizing three basic types of flow measuring techniques which is rotameter , venturi and orifice .The flowrate is the volume of fluid which passes per unit time represented by unit Q.

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Since the percentage error for this experiment from A-Z is not more than 15% so it is considered as successful experiment . By referring percentage of error that we calculated by comparing to time flowrate for rotameter , orifice and venture is 7.90% , 4.71% and 5.49% . Its can be conclude that percentage error for orifice is the lowest and make it the best device for calculate flow rate . But from the theory, venturi meter is a more accurate than orifice and rota meter. From the calculation, we determine that orifice meter is more accurate than others. Actually, it should be the venturi meter. We found that one of the major factors that affect the readings is the bubble in pipeline. Besides that, the position of eyes also gives effect to the manometer reading. For experiment 2, the objective is to investigate the lost coefficient of fluid through 90 degree elbow. From the graph that have been plotted, gradient (K) of the graph is 0.1228. But the actual theoretical value is 0.3 for Elbow flanged regular 90°. The percentage error for this experiment is 57%. So it is considered the experiment is unsuccessful. We assumed the experiment is considered fail because the percentage exceeded 15%. This occurrence may be caused by bubble that trap inside the tube that connected to manometer.

CONCLUSION As a conclusion for experiment 1, we can say that the most accurate flow meter is a venturi meter. From this experiment, we determine that the flow rate % error for venturi

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meter is higher than the orifice meter. From the theory, the more efficiency of flow meter has a less flow rate % error. As a conclusion for experiment 2, we can state that the loss coefficient is 0.1228. Percentage difference for the experiment is 57%. The experiment is unsuccessful.

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RECOMMENDATION: There are some precautions and suggestions that can be taken for safety and to get better result when conducting the experiment of Flow Measurement Apparatus experiment. The recommendations are as followed:

1. Before starting the experiment, students must follow all the instructions from the supervisor and do general set-up procedures . 2. Avoid error in taking readings and make sure eyes of observer are parallel to the reading scale.

3. The observer must be fixed to one person only to measure the apparatus reading to avoid perspective errors.

4. The experiment must be conduct at least twice to obtained average result. 5. Make sure to follow the shut-down procedures after finishing the experiment.

REFERENCE:     

https://en.wikipedia.org/wiki/Flow_measurement https://www.mathesongas.com/pdfs/.../flowmeter-product-line-overview Lab manual, Faculty of Chemical Engineering, UiTM Shah Alam https://www.youtube.com/watch?v=Ml0bhxtur9I Google search keyword “rotameter , venture , orifice ,flowrate



demonstration” www.engineeringtoolbox.com/

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APPENDICES

Figure 1: APPARATUS

Figure 2: Venturi meter and manometer

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Figure 3: Rotometer and Discharge Valve

Figure 4: 90 degree elbow

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Figure 5: Orifice meter

Figure 6: Control Valve

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290840829-Flowmeter-Demonstration-Lab-Report.docx

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