Lab 4 (Thermofluids Lab)

UNIVERSITI TEKNOLOGI MARA FAKULTI KEJURUTERAAN KIMIA THERMOFLUIDS LABORATORY

(CGE 536)

No. Title Allocated Marks (%) Marks1 Abstract/Summary 5 2 Introduction 5 3 Aims/Objectives 5 4 Theory 5 5 Apparatus 5 6 Procedures 10 7 Result 10 8 Calculations 10 9 Discussion 20 10 Conclusion 10 11 Recommendations 5 12 References 5 13 Appendices 5

TOTAL MARKS 100

Remarks:

Checked by :

Date :

NAME : 1) MUHAMMAD ROZAIRY BIN ROSLAN (2015829256)

2) MUHAMMAD QAYYUM BIN AZMAN (2015840046)

3) MUHAMAD ADNAN BIN ZAINAL ABIDIN (201520891204)

4) RABIATUL ADAWIYAH BINTI HAMDI (2015238424)

5) MOHAMMAD FITRI BIN ABU BAKAR (2015674008)

EXPERIMENT : FLOWMETER DEMONSTRATION

DATE PERFORMED: 29TH MARCH 2016

GROUP : GROUP 3 (EH2433B)

ABSTRACT

The aim of this experiment is to investigate and demonstrate the operation and characteristic

three type of flow meter including its accuracy and energy losses. The hydraulic bench as

well as the Flow Meter Demonstration Unit was used as the apparatus in this experiment.

There are three different type of flow meter which is the Orifice Meter, Venturi Meter, and

Rotameter that we need to identified at the beginning of the experiment. All three flow meter

were placed in the unit and each flow meter was different from the other two in term of area

and flow rates. In Venturi meter and Orifice meter, the output is not linear with the flow rate,

Q as both can only measure the output. On the other hand, Rotameter output which is directly

proportional to the flow rate can be measured and the pressure difference can be neglected.

The average timed flow rate, Qt was calculated to be 5.4022 L/min , while the average

Venturi Meter flow rate, Qv is 5.6581 L/min, the Rotameter average, Qr is calculated to be

5.4025 L/min and lastly the average flow rate for Orifice Meter, Qo approximately 5.1451

L/min. Hence, the average velocity and velocity head are 3.0012×10-2 mm/s and 4.5908×10-5

mm respectively.

INTRODUCTION

Fluid mechanics has developed an analytical discipline from the application of the classical

laws of static, dynamics and thermodynamics. It was the situation in which fluids can be

treated as continuous media. The particular laws involved are those of the conversation of

mass. For the information, this law may be simplified in an attempt to describe quantitatively

the behaviour of the fluids.

The hydraulic bench service module (F1-10) provides the necessary facilities to

support a comprehensive range of hydraulic models each of which is designed to demonstrate

particular aspects of hydraulic theory.

The specific hydraulic model that is concerned for this experiment is the flow meter

test rig (F1-21). This consists of venture meter, variable area meter or rotameter and orifice

plate installed in a series of configurations to allow for direct comparisons.

Figure 1 Venturi meter

Figure 2 Orifice meter

Figure 3 Rotameter

Venturi meter

Venturi meter is a tube with constricted throat that increase velocity and decrease pressure.

Venturi meter is used to measure the flow rate of compressible and incompressible fluid in a

pipeline. When a fluid flows through a throat section, which has smaller cross section area

than in a pipe, the velocity of the fluid through a throat is higher than in the pipe. If velocity

higher, the pressure will drop. By measuring pressure drop, discharge may be calculated.

Beyond the throat, the fluid is decelerated in a pipe of slowly diverging section in order to

recover as much of the kinetic energy as possible. In order to understand the principles of

venturi meter, we must know the principle of Bernoulli’s equation.

Orifice plate

The orifice meter is also used in order to measure the flow rate of a reservoir or through a

pipe. The orifice meter consists of a flat plate with circular hole drilled in it. There is pressure

tap upstream from the orifice plate and another just downstream.

Rotameter

The rotameter is a simple, reliable, inexpensive and easy to install flow meter with low

pressure drop and no electrical connection that gives a direct reading of flow rate for a wide

range of liquids and gases.

OBJECTIVES

To investigate and contrast the operation and characteristics of three different basics

types of flow meter which venture, variable, and orifice including accuracy and

energy loss.

To measure a pressure drop at different segment of device.

To determine a flow rate through a pipe.

THEORY

The applications of the Bernoulli’s equation yield the following result which applies for both

the Venturi meter and Orifice plate.

Bernoulli’s equation:

P1ρg

+V 12

2 g+Z1=P2

ρg+V 22

2g+Z2

Z1=Z2

P1−P2ρg

=V 22−V 12

2g…..(1)

Q 1=Q2

A1V 1=A2V 2

V 1= A 2V 2A1

… ..(2)

(2) In (1):

P1−P2ρg

=V 22−¿¿

V 22[1−( A2A1 )

2

]

2g=∆Pρg

V 2= 1

√ [1−( A2A1 )

2

]. √2∆ P

√ ρ…..(3)

Q=CdA 2V 2… ..(4)

(3) In (4):

FLOW RATE ,QY= CdA 2

√ [1−( A2A1 )

2

]. √2 ∆P

√ ρ

√2∆ P=√2 g∆h√ ρ

∆h: head difference in meter from the manometer readings for the appropriate meter (m)

g: acceleration due to gravity (m/s2)

Cd: discharge coefficient for meter

A1: area of the test pipe upstream of the meter (m2)

A2: throat area of the meter (m2)

Use of discharge coefficient, Cd is necessary because of the simplifying assumptions

made when applying the Bernoulli’s equations. Values of this coefficient are determined by

experiment.

The energy loss that occurs in a pipe fitting is commonly expressed in term of head

loss and can determine from the manometer readings. For this experiment, head losses will be

compared against the square of the flow rate used. In addition, pressure loss for venturi and

rotameter are low and for orifice meter is medium.

APPARATUS

1. Manometer

2. Discharge Valve

3. Water outlet

4. Venturi meter

5. Staddle Valve

6. Rotameter

7. 90° Elbow

8. Orifice

9. Pump

PROCEDURES

2

1

3

4

9

8

7

5

6

General Start-up Procedures

The Flow meter Measurement Apparatus (Model: FM 101) is designed ready

for use and only requires connection to the Hydraulic Bench (Model: FM 110)

as follows:

a) The apparatus is placed on the top of a suitable hydraulic bench.

b) The apparatus on the bench top is level.

c) The hydraulic coupling is connected the outlet supply of the hydraulic

bench.

d) The discharge of the flow apparatus hose is connected to the collection

tank of the hydraulic bench.

e) The apparatus are ready to start.

Starting up the Apparatus:

1. The flow control valve of hydraulic bench is fully closed and the

discharge valve is fully opened.

2. Ensure that the discharge hose is properly directed to volumetric tank

of fiberglass before starting up system and that volumetric tank drain

valve is left opened to ensure flow discharge back into sump tank.

3. When step (b) is confirmed start up, the pump supply from hydraulic

bench. The bench valve is opened slowly. Then, the water flowing

were seen from hydraulic bench through to the flow apparatus and

discharge through into the volumetric tank of hydraulic bench and next

drained back into sump tank of hydraulic bench.

4. Next, the flow control valve is fully opened. When the flow in the pipe

is steady and there is no trapped bubble, then the bench valve start to

close to reduce the flow to the maximum measurable flow rate.

5. Then, the water level in the manometer board are seen that display the

different level water of heights. (If the water level in the manometer

board is too high where it is out of visible point, the water level is

adjusted by using the staddle valve. With the maximum measurable

flow rate, retain maximum readings on manometer.

6. At this point, slowly reduce the flow by controlling the flow discharge

valve of apparatus: the discharge valve totally closed.

7. The water level in the manometer board began seen to level into a

straight level. This level at the lower or at higher end of the

manometer board range. (Take note that the pump from the hydraulic

bench is at this time, still supplying water at a certain pressure in the

system).

8. Then, also be on the lookout for “Trapped Bubbles” in the glass tube or

plastic transfer tube. This should remove from the system for better

accuracy. Slowly “press the plastic tube to push the bubbles up or

lightly “tab” the glass tube to release the bubbles upwards.

Demonstration of the operation and characteristic of three different basic types

of flowmeter

Procedures:

1. The apparatus was placed on bench. The inlet pipe is connected to bench

supply while the outlet pipe is connected into volumetric tank.

2. The bench valve is fully closed and the discharge valve is fully opened,

then the pump supply was started from hydraulic bench.

3. The bench valve was slowly opened until it was fully opened.

4. When the flow in the pipe is steady and there is no trapped bubble, the

bench valve is started to close to reduce the flow to the maximum

measurable flow rate.

5. The water level in the manometer board was adjusted by using the air

bleed screw. The maximum readings on manometer were retained with the

measurable flow rate.

6. The readings on manometer (A-J), rotameter and measured flow rate were

noted.

7. Step 6 is repeated for different flow rates. The flow rates can be adjusted

by utilizing both bench valve and discharge valve.

8. To demonstrate similar flow rates at different system static pressures, the

bench and flow control valve are adjusted together and manometer level as

required.

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

Procedures:

1. The apparatus was placed on bench. The inlet pipe is connected to bench

supply while the outlet pipe is connected into volumetric tank.

2. The bench valve is fully closed and the discharge valve is fully opened,

then the pump supply was started from hydraulic bench.

3. The bench valve was slowly opened until it was fully opened.

4. When the flow in the pipe is steady and there is no trapped bubble, the

bench valve is started to close to reduce the flow to the maximum

measurable flow rate

5. The water level in the manometer board was adjusted by using the air

bleed screw. The maximum readings on manometer were retained with the

measurable flow rate

6. The readings on manometer (I and J) and measured flow rate were noted.

7. Step 6 is repeated for different flow rates. The flow rates were adjusted by

utilizing both bench valve and discharge valve.

8. The tables were completed below.

9. The graph H against

Vs2

2 g for 90 degree elbow was plotted to determine

the coefficient of losses.

General Shut-down Procedures

1. The water supply valve and venturi discharge valve was closed.

2. The water supply pump was turned off.

3. The water from the unit was drained off when not in used.

RESULTS

RotameterFlowrate (L/min)

Manometer Reading(mm)

A B C D E F G H I J5 239 238 229 236 238 240 240 220 228 22710 260 255 221 242 248 253 253 170 203 20115 312 300 232 276 286 295 295 126 190 18920 374 353 231 310 330 348 348 30 154 148

Table 1.1

RotameterFlowrate, Qt(L/min)

Volume(L) Time (s)

Flowrate,Qa

(L/min)

Flowrate Calculated Using

Bernoulli’s Equation, Qt

(L/min)T1 T2 T3 Average Venturi Orifice Venturi Orifice

5 3 30.57 34.01 35.39 33.32 5.4025 5.4025 5.6581 5.145110 3 15.94 15.94 18.28 16.72 10.7643 10.7643 11.1738 10.482015 3 10.59 12.47 12.94 12.00 15.0000 15.0000 16.0032 14.956220 3 7.64 8.44 9.38 8.47 21.2465 21.2465 21.3960 20.5158

Table 1.2

Volume

(L)

Time(s)

Time(min)

Flowrate,Qa

(L/min)

ManometerReading

(mm)

DifferentialPiezometerHead, Δh’

(mm)

V(mm/s)

V ²2g

(mm)

I J Elbow (hi – hj)3 33.32 0.5553 5.4025 228 227 1 3.0012 × 10−2 4.5908 × 10−5

3 16.72 0.2787 10.7643 203 201 2 1.1962 × 10−1 7.2930 × 10−4

3 12.00 0.2000 15.0000 190 189 1 8.3333 × 10−2 3.5394 × 10−4

3 8.47 0.1412 21.2465 154 148 6 7.0838 × 10−1 2.5576 × 10−2

Table 1.3

CALCULATIONS

1. Sample Calculations for Actual Flowrate, Qa

Flowrate, Q (L/min) = Volume(L)Time (min)

Rotameter Flowrate, Qt (L/min) Calculations

5

Flowrate, Q (L/min) = 3 L

0.5553min = 5.4025

10


0.2787min = 10.7643

15


0.2000min = 15.0000

20

Flowrate, Q (L/min) = 3L

0.1412min = 21.2465

2. Sample Calculation of Area of the Cross Section, A (A, B, C, D, E, F, G and H) Using

Continuity Equation

A1 = πD ²

4

A = Area of the cross section A, B, C, D, E, F, G and H (m²)

D = Diameter of the cross section A, B, C, D, E, F, G and H (m)

Water Head Area

AA1 =

π (0.0260m) ²4

= 5.3093 × 10−4m²

BA1 =

π (0.0216m) ²4

= 3.6644 × 10−4m²

CA1 =

π (0.0160m) ²4

= 2.0106 × 10−4m²

DA1 =

π (0.0200m) ²4

= 3.1416 × 10−4m²

EA1 = π (0.0220m) ²

4

= 3.8013 × 10−4m²

FA1 =

π (0.0260m) ²4

= 5.3093 × 10−4m²

GA1 = π (0.0260m) ²

4

= 5.3093 × 10−4m²

HA1 = π (0.0160m) ²

4

= 2.0106 × 10−4m²

3. Sample Calculation of Actual Flowrate for Venturi Meter Using Bernoulli’s and Continuity Equation

Qt = Cd × At × [ 1 - (AtA

) ² ¿−1/2 [2g (Ha – Hc)¿1 /2

Where,

Cd = Coefficient of discharge (0.98)

At = Throat area (16mm)

A = Inlet area (5.3093 × 10−4m²)

G = 9.81 m/s²

Ha = Manometer reading at A (m)

Hc = Manometer reading at C (m)

Example:

When the flowrate of rotameter is 5 L/min

Qt = 0.98 × 2.0106 × 10−4m² × [1 - ( 2.0106×10−4m ²5.3093×10−4m ²

)² ¿−1/2 [2(9.81 m/s²) (0.239 – 0.229)

¿1 /2

= 9.4301 × 10−5 m³/s


Qt = 0.98 × 2.0106 × 10−4m² × [1 - ( 2.0106×10−4m ²5.3093×10−4m ²

)² ¿−1/2 [2(9.81 m/s²) (0.260 – 0.221)

¿1 /2

= 1.8623 × 10−4 m³/s


Qt = 0.98 × 2.0106 × 10−4m² × [1 - ( 2.0106×10−4m ²5.3093×10−4m ²

)² ¿−1/2 [2(9.81 m/s²) (0.312 – 0.232)

¿1 /2

= 2.6672 × 10−4 m³/s


Qt = 0.98 × 2.0106 × 10−4m² × [1 - ( 2.0106×10−4m ²5.3093×10−4m ²

)² ¿−1/2 [2(9.81 m/s²) (0.374 – 0.231)

¿1 /2

= 3.5660 × 10−4 m³/s

4. Sample Calculation of Actual Flowrate for Orifice Meter Using Bernoulli’s and

Continuity Equation

Qt = Cd × At × [ 1 - (AtA

) ² ¿−1/2 [2g (Hg – Hh)¿1 /2

Where,

Cd = Coefficient of discharge (0.63)

At = Orifice area (2.011 × 10−4 m²)

A = Orifice upstream area (5.3093 × 10−4m²)

g = 9.81 m/s²

Hg = Manometer reading at G (m)

Hh = Manometer reading at H (m)

Example:

When the rotameter flowrate is 5 L/min

Qt = 0.63 × 2.011 × 10−4m² × [1 - ( 2.011×10−4m ²5.3093×10−4m ²

) ² ¿−1/2 [2(9.81 m/s²) (0.240 – 0.220)¿1 /2

= 8.5752 × 10−5 m³/s


Qt = 0.63 × 2.011 × 10−4m² × [1 - ( 2.011×10−4m ²5.3093×10−4m ²

) ² ¿−1/2 [2(9.81 m/s²) (0.253 – 0.170)¿1 /2

= 1.7470 × 10−4 m³/s


Qt = 0.63 × 2.011 × 10−4m² × [1 - ( 2.011×10−4m ²5.3093×10−4m ²

) ² ¿−1/2 [2(9.81 m/s²) (0.295 – 0.126)¿1 /2

= 2.4927 × 10−4 m³/s


Qt = 0.63 × 2.011 × 10−4m² × [1 - ( 2.011×10−4m ²5.3093×10−4m ²

) ² ¿−1/2 [2(9.81 m/s²) (0.348 – 0.030)¿1 /2

= 3.4193 × 10−4 m³/s

5. Conversion of the flowrates obtained for Venturi and Orifice Meter from Qt (m³/s)

to Qt (L/min)

Example:

Venturi Meter

a. Qt = 9.4301 × 10−5 m³/s × (1000 L/1 m³) (60 s/1 min)

= 5.6581 L/min

b. Qt = 1.8623 × 10−4 m³/s × (1000 L/1 m³) (60 s/1 min)

= 11.1738 L/min

c. Qt = 2.6672 × 10−4 m³/s × (1000 L/1 m³) (60 s/1 min)

= 16.0032 L/min

d. Qt = 3.5660 × 10−4 m³/s × (1000 L/1 m³) (60 s/1 min)

= 21.3960 L/min

Orifice Meter

a. Qt = 8.5752 × 10−5 m³/s × (1000 L/1 m³) (60 s/1 min)

= 5.1451 L/min

b. Qt = 1.7470 × 10−4 m³/s × (1000 L/1 m³) (60 s/1 min)

= 10.4820 L/min

c. Qt = 2.4927 × 10−4 m³/s × (1000 L/1 m³) (60 s/1 min)

= 14.9562 L/min

d. Qt = 3.4193 × 10−4 m³/s × (1000 L/1 m³) (60 s/1 min)

= 20.5158 L/min

6. Sample Calculation for the Velocity of water Flowing through the 90⁰ Elbow

Velocity of Water (m/s) = DifferentialPiezometer Head , Δh' (mm)

Time(s)


5 V = 1mm

33.32 s

= 3.0012 × 10−2 mm/s

10 V = 2mm

16.72 s

= 1.1962 × 10−1 mm/s

15 V = 1mm

12.00 s

= 8.3333 × 10−2 mm/s

20 V = 6mm8.47 s

= 7.0838 × 10−1 mm/s

7. Sample Calculation for V ²2g


5V ²2g = (3.0012×10−2mm /s) ²

2(9810mm/ s ²)

= 4.5908 × 10−5mm

10V ²2g = (1.1962×10−1mm/ s) ²

2(9810mm/ s ²)

= 7.2930 × 10−4mm

15V ²2g = (8.3333×10−2mm /s) ²

2(9810mm /s ²)

= 3.5394 × 10−4mm

20V ²2g = (7.0838×10−1mm /s) ²

2(9810mm /s ²)

= 3.6105 × 10−2mm

DISCUSSION

The Flow Meter Demonstration is to demonstrate three different type of flow meter,

Rotameter, Venturi Meter and Orifice Meter. Based on the reading that was taken during the

experiment, the flow rate for all three flow meter can be calculated as well as the head

velocity.

In this experiment, the characteristic and operations of all three Venturi Meter,

Orifice Meter, and Rotameter can be seen. During the experiment, we can determine which

one of the flow meter gives the accurate value based on all the readings that have been

recorded. The value of flow rate of all three flow meter can be determined after the

experiments have been conducted. The results from this experiment give us the average flow

rate for Rotameter is 5.4025 L/min, Venturi Meter is 5.6581 L/min, and 5.1451 L/min for the

Orifice Meter.

Venturi Meter is more accurate than Orifice Meter and Rotameter theoretically. If

the result obtained differ from the theory, there must be some error occurs during the

experiment. One of the major factors that affect the reading is the bubble in pipeline or

manometer tubes. Besides that, if the eye is not perpendicular to the water level, an error

called the parallax error might occur during the reading was taken. More calibration along the

manometer will result in more accurate reading. Venturi Meter is the precise flow meter in

measuring flow rate of any fluid because of it diverge portion which increase the velocity and

reduces the friction loss of fluid that pass through it.

Generally, Orifice Meter which consist of orifice plate inherit the advantages of

being easy and inexpensive to replace, low cost maintenance, but initial installation may be

costly due to special orifice-plate flanges containing pressure taps. However, most important

advantages in Orifice Meter is that it has no moving parts and its differential pressure sensor

can easily being removed and replaced without shutting down the process. Meanwhile, the

advantages of Venturi Meter compared to Orifice Meter are the capacity of Venturi Meter to

handle more flow while imposing less permanent pressure loss on the system and also its

greater accuracy over a wider flow rate range with its ability to be used by fluid containing of

relatively high percentage entailer solids.

RECOMMENDATION

After conducting this experiment, we can say that value of flow rate and the flow rate

% error is different from the theoretical results. From the theory, the most accurate flow

meter is the venturi meter. So, it means that the most efficiency flow meter has a less value of

flow rate % error. In this experiment, the value of flow rate % error for venturi meter is

higher than the orifice meter. For the first recommendation for this experiment is make sure

that there is no bubble in the pipeline. The existence of bubble may cause less accuracy in the

reading of the flow meter. The second is to make sure there is no small particles or

contaminant in the fluid because some of the devices are very sensitive to these particles.

Besides that, during recording the manometer reading, make sure the position of our eyes is

parallel to the level of reading or the miniscus of the fluid level.

REFERENCES

1. Laboratory Manual CGE536, Faculty of Chemical Engineering, UiTM Shah Alam,

Malaysia

2. Fluid Mechanics, Fundamental and Applications, Yunus A. Cengel and John

M.Cimbala, Mc Graw Hill.

3. Engineering Fluid Mechanics, John Roberson & Clayton Crowe, Houghton Mifflin

Co, Chapter 13.

4. Yahoo and Google search engines (keyword: flowmeter, venturi meter, orifice meter)

APPENDICES

Lab 4 (Thermofluids Lab)

Documents

Transcript of Lab 4 (Thermofluids Lab)