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DECEMBER 2013 COMMON TEST

School of Life Sciences & Chemical Technology(Diploma in Chemical and Biomolecular Engineering)

Level 2 Time Allowed: 1.5 Hours

TRANSFER PROCESSES - FLUID FLOW

INSTRUCTIONS TO CANDIDATES:

1. Answer all questions.

2. The following tables and charts are appended as Appendices 1 to 4.Chart A - Friction Factor Chart (Appendix 1)Table A - Constants and Coefficients(Appendix 2)

Table B - Formulae & Equations (Appendix 3)Table C - Properties of water (Appendix 4)

3. This paper consists of 7 pages including this cover page. Check carefully tomake sure your set is complete.

QUESTION 1 (20 marks)

1.1 A pipeline of 100 mm diameter conveying water at a velocity of 2.5 m/sbranches into two pipes of 50 mm and 75 mm as shown in Figure 1.1. If thevelocity in the 75 mm pipe is 1.8 m/s, determine the velocity of flow in the 50mm pipe and the total flow rate in 100 mm pipe.

Figure 1.1(10 marks)

1.2 Water at 25C flows at the rate of 0.25 m3/s through a 200 mm diameter pipe.The pipe enlarges suddenly to 450 mm diameter. Further downstream thepipe diameter contract suddenly to 250 mm diameter as shown Figure 1.2.Calculate(a) the head loss due to the sudden expansion(b) the head loss due to the sudden contraction(c) the head losses at the entrance from and the exit to the water tanks.

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2.1 If 30 litres of a liquid has a mass of 15 kg, determine its mass density, weightdensity and specific gravity.

(6 marks)

2.2 Water at 20C flows out of a tank through a siphon formed by a bent pipe, 25mm in diameter as shown in Figure 2.1. The pipe discharges into theatmosphere at C. The absolute atmospheric pressure is 101.325 kN/m2. Theenergy loss in the whole length of the pipe is equivalent to a total of[60(v2/2g)] m head of water. Calculate(a) the volumetric flow rate through the pipe(b) the absolute pressure at B.

B

9 m

A2 m

0.4 m 5 m

C



3.1 A pipe of 25 mm diameter carries water at 35C flowing with a velocity of 1.6m/s. Calculate the Reynolds number and determine the type of flow.

(6 marks)

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3.2 Water at 30C flows in a 250 mm diameter wrought iron pipeline over adistance of 2.5 km with a velocity of 1.4 m/s. The pipeline contains fittings asfollows: two fully open gate valves, two swing check valves, seven 90standard elbows, and three long radius 90 elbows. Calculate:(a) the head loss due to friction in the pipeline

(b) the head loss due to all the fittings using equivalent length method(14 marks)


4.1 Define steady non-uniform flowand unsteady uniform flow.(6 marks)

4.2 A pipeline is designed to convey water flowing at 25C from Upper PeirceReservoir to Lower Peirce Reservoir as shown in Figure 4.1. The difference inwater level between the two reservoirs is 15 m and the length of the pipelineis 13 km. The total localised fittings losses amount to [10(V2/2g)]. Theentrance from and exit to the reservoirs are sharp. Determine the volumetricflow rate if the diameter of the coated cast iron pipeline is 500 mm.


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Appendix 1

Chart A: Friction Factor Chart (Source: Mott, R. L., Applied Fluid Mechanics, 6 thedition, 2006)

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Appendix 2Table A: Constants and Coefficients

Universal Constants

Acceleration due to gravity 9.81 m/s2

Specific gravity of mercury 13.6Standard atmospheric pressure 101.325 kN/m absolute value

Universal gas constant 8.314 kJ/kmol-K

Recommended Roughness Values of e (in mm)

Spun iron 0.03

Wrought iron 0.05

Uncoated steel 0.03

Coated steel 0.06

Galvanised iron 0.15

Coated cast iron 0.12Cast iron 0.25

Concrete (class 4) 0.15




Loss Coefficients for Pipe Fittings

Fittings Values ofD

Le

Coefficients, k

Screwed ends Flanged ends

Globe Valve Fully OpenConventionalY-Pattern

400 10 5

160 4 2

Gate ValveFully Open75% Open50% Open25% Open

13 0.2 0.1

35 1 0.5

260 5.6 2.8

900 24 12

Tee line flow 20 0.9 0.2

Tee Branch branch flow 60 2 1

Standard 90elbow 30 0.9 0.3

Standard 45elbow 16 0.4 0.2

Long radius 90elbow 20 0.6 0.2

Return Bend 50 2.2 0.4

Standard 45bend 15 0.2

SwingCheck Valve 135 2.5

Plug Valve 18 0.324

Ball Valve Fully Open 3 0.05

Angle valve Fully Open 145 5

Foot valve 75 15Butterfly valves 40 0.4

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Appendix 3Table B: Formulae & Equations

Energy Equation

Darcy`s Head Loss

Reynolds No

Venturi meter

[ ]Orifice meter

Pitot-static tube:

Local Head Loss

Sudden contraction head loss

(

)

Sudden expansion head loss

(

)

Single stage isothermal compressor: () ()Single stage compressor: ()

Multi-stage Compressors (Inter-stagecooling) Optimum compression ratio

()

Multi-stage Compressors ()

Multi-stage Compressors (Inter-stage cooling)(Adiabatic/Isentropic)

( ) () ( ) () Pump Affinity Laws () ()Pump Impeller Size

Pump Specific Speed

HydraulicPower

Pump Efficiency ()

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Appendix 4Table CProperties of water

Properties of water at various temperatures

Temperature (C) Density (kg/m3) Dynamic Viscosity (Ns/m2)

0 1000 1.79 X 10- 5 1000 1.52 X 10-

10 1000 1.31 X 10-

15 999 1.14 X 10-3

20 998 1.00 X 10-

25 997 0.89 X 10-3

30 996 0.80 X 10-

35 994 0.72 X 10-

40 992 0.65 X 10-3

45 990 0.60 X 10-

50 988 0.55 X 10-355 986 0.51 X 10-

60 983 0.469 X 10-

65 980 0.437 X 10-

70 978 0.406 X 10-

75 975 0.380 X 10-3

80 972 0.356 X 10-

85 969 0.335 X 10-3

90 965 0.316 X 10-

95 962 0.299 X 10-3

100 958 0.284 X 10-

END OF PAPER

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JUNE 2013 COMMON TEST

School of Life Sciences & Chemical Technology(Diploma in Environmental & Water Technology)

Level 2 Time Allowed: 1.5 Hours

TRANSFER PROCESSES - FLUID FLOW

INSTRUCTIONS TO CANDIDATES:

1. Answer all questions.

2. The following tables and charts are appended as Appendices 1 to 3.

Chart A - Friction Factor Chart (Appendix 1)Table A - Constants and Coefficients(Appendix 2)Table B - Useful Formulae (Appendix 3)

3. This paper consists of 6 pages including this cover page. Check carefully tomake sure your set is complete.


(a) Calculate the density and the specific gravity of 24 litres of a liquid having amass of 18 kg.

(b) Oil flows at the rate of 3 L/s through a 50 mm diameter pipe which expandsuddenly to 75 mm diameter pipe. Further downstream the pipe contractsuddenly to a 35 mm diameter pipe. Calculate:(i) head loss due to the sudden expansion

(ii) head loss due to the sudden contraction

(c) A pipeline of 250 mm diameter carrying water at an average velocity of 3.5m/s branches into two pipes of 150 mm and 200 mm diameters. If the averagevelocity in the 150 mm pipe is 2 m/s, determine the average velocity of flow inthe 200 mm pipe and the total flow rate in the 250 mm diameter pipe.

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(a) Water flows in a 250 mm diameter pipeline between pumps with a velocity of1.7 m/s and a frictional factor of 0.02. The pipe contains fittings as follows:

three fully open gate valves, two check valve, six 900

standard elbows andone long radius 900 elbows. Calculate the head loss due to all the fittingsusing equivalent length method.

(b) Water flows at a rate of 15 L/s in a horizontal galvanised iron pipe of 200 mmdiameter. If the pipe is of uniform diameter, determine head loss due tofrictional resistance in 400 m length of pipe? What is the pressure drop in thislength of pipe?


(a) A pipe of diameter 75 mm carries water at a flow rate of 8 L/s for a distance of20 m. The pressure in the pipe at the upstream end is 25 kPa and at thedownstream end the pipe has decreased in elevation by 1.5 m. Assuming thehead loss is 0.5(v2/2g) per meter length of pipe, Calculate the pressure at thedownstream end.

(b) Oil with specific gravity 0.8 is pump through a uniform 30 mm diameter pipe ata flow rate of 0.03 m3/s. Calculate the pump head required given that the totalhead loss in the system is 15 m. Neglect all other head losses in the system.

oil

P= 45 kPaPressurized

um

8

3

S.G = 0.8

4 m ID

5 m ID

S.G = 0.8

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A pump is used to pump oil of specific gravity 0.85 and dynamic viscosity 0.006Pa.s as shown in Figure b e l o w . O i l is pumped from tank and discharged tothe atmosphere through a 100 mm diameter pipeline, 150 m long commercial steel

pipe. The oil level in tank is 8 m below the discharge point to the atmosphere. Theoil in the tank is open to the atmospheric pressure. The entrance from thetank to the pipe is sharp-edged and all fitting head loss in the piping system is 7times the velocity head (7V2/2g). If the head developed by the pump is 30 m,calculate discharge from the pipe in m3/s.

8 m

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Appendix 1

Chart A: Friction Factor Chart (Source: Mott, R. L., Applied Fluid Mechanics, 6 thedition, 2006)

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Appendix 2Table A: Constants and Coefficients

Constants

Acceleration due to gravity 9.81 m/s2Specific gravity of mercury 13.6

Water density 1000 kg/m

Water viscosity 0.001 Ns/m

Standard atmospheric pressure 101.325 KN/m absolute value

Loss Coefficients for Pipe Fittings

Values ofD

Le Loss Coefficients, k

Fittings

D

Le

Screwed ends Flanged ends

Globe ValveConventionalY-Pattern

400 10 5

160

Gate ValveFully Open75% Open50% Open25% Open

10 0.2 0.1

35

150

900

Standard Tee Run 10 0.9 0.2Standard Tee Branch 60 2 1

90Standard Elbow 30 0.9 0.3

45Standard Elbow 16 0.4 0.290oLong Radius Elbow 20 0.6 0.2

Return Bend 50 2.2 0.4Check Valve 50 2.5

Plug Valve 18 0.324

Ball Valve (FullyOpen)

30.05

Angle valve 55 5

Foot valve 75 1.5

Loss coefficients for sudden contraction Kc 0 0.2 0.4 0.6 0.8 1.0Kc 0.5 0.4 0.3 0.2 0.1 0

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Appendix 3Table B: Formulae

Energy Equation

Darcy`s Head Loss

Reynolds No

Orifice meter

[ ]Venturi meter

Pitot-static tube:

Sudden contraction (entrance loss)

Sudden expansion (exit loss)

Sudden contraction head loss (withinpipe channel) ( )

Sudden expansion head loss (withinpipe channel) ( )

Single stage isothermal compressor: () ()Single stage compressor: ()

Multi-stage CompressorsOptimum compression ratio

()Multi-stage Compressors

()

Multi-stage Compressors (Adiabatic Process)

( ) () ( ) ()

Pump Affinity Laws

(

)

(

)

Pump Impeller Size Pump Specific Speed

Pump Power Pump Efficiency ()

END OF PAPER

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