Assignment Sheet No 2_2016

8/18/2019 Assignment Sheet No 2_2016

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ASSIGNMENT SHEET NO 2_2016

Some useful data for solving the numerical is given at the end of this sheert!

Problem 1

An evaporative cooling tower as shown in the sketch above is used to ccol water from110o to 80o F. Water enters the tower at a rate of 250,000 lbm/hr. Dry air (no watervapor) flows into the tower at the rate of 151,000 lbm/hr. If the rate of wet air flow outof the tower is 156,000 lbm/hr., determine the rate of water evaporation in lbm/hr andthe rate of cooled water flow in lbm/hr.

Problem 2Fresh water flows steadily into an open 250 liters drum initially filled by sea water. Thedensity of sea water is 1040 Kg/m3. The fresh water mixes thoroughly with the sea

water and the mixture overflows out of the drum. If the fresh water flow rate is 60liters/min, estimate the time required to decrease the density of mixture to 1020 Kg/m3.

Problem 3

As shown in the diagram above, at the entrance to a 3-ft-wide channel the velocitydistribution is uniform with a velocity V. Further downstream the velocity profile isgiven by u = 4y – 2y2, where u is in ft/sec and y is in ft. Determine the value of V.


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Problem 4

Air flows steadily between two cross sections in a a long, straight section of 12-in-insidediameter pipe. The static temperature and pressure at each section are indicated in thediagram above. If the average air velocity at section (2) is 320 m/sec, determine theaverage air velocity at section (1). Determine the frictional force exerted by the pipe wall

on the air between sections (1) and (2). Assume average velocity distribution at eachsection,

Problem 5

Determine the magnitude and direction of the anchoring force needed to hold thehorizontal elbow and nozzle combination shown in the diagram above in place. Theatmospheric pressure is 100 kPa(abs). The gauge pressure at section (1) is 100 kPa. Atsection (2), the water exits to atmosphere.


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Problem 6

The hydraulic dredge shown in the diagram above is used to dredge sand from a riverbottom. Estimate the thrust needed from the propeller of the dredge to hold the boatstationary. Assume the sand/water mixture has SG = 1.2.

Problem 7

A simplified sketch of a hydraulic turbine runner is shown in the sketch above. Relativeto the rotating runner, water enters at section (1) [cylindrical cross section area A1 at r1 =1.5 m] at an angle of 1000 from the tangential direction and leaves at section (2)[cylindrical cross section area A2 at r2 = 0.85 m] at an angle of 500 from the tangentialdirection. The blade height at sections (1) and (2) is 0.45 m and the volume flow ratethrough the turbine is 30 m3/sec. The runner speed is 130 RPM in the direction shown.Determine the shaft power developed.


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Problem 8

The front and side views of a centrifugal pump rotor or impeller are shown in the figureabove. If the pump delivers 200 liters/sec of water and the blade exit angle is 35 0 fromthe tangential direction, determine the power requirement associated with the flowleaving at the blade angle. The floe entering the rotor blade row is essentially radial asviewed from a stationary frame.

Problem 9

Water flows in a 100-ft-wide river with a flow rate of 2400 ft3/sec, over a rock pile, asshown in the diagram above. Determine the direction of flow and the head lossassociated with the flow across the rock pile.


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Problem 10

An incompressible liquid flows steadily along the inclined pipe, as shown in thediagram above. Determine the direction of flow and the head loss over the 6-m lengthof pipe.

Problem 11

Water flows through a valve, as shown above, at the rate of 1000 lbm/sec. The pressure just upstream of the valve is 90 psi and the pressure drop across the valve is 50 psi. Theinside diameters of the valve inlet and exit pipes are 12 and 24 in. If the flow throughthe valve occurs in a horizontal plane determine the loss in available energy across thevalve.

Problem 12An automobile engine will work best when the back pressure at the interface of theexhaust manifold and the engine block is minimized. Show how reduction of losses inthe exhaust manifold, piping and muffler will also reduce the back pressure. How couldlosses in the exhaust system be reduced? What primarily limits the minimization ofexhaust system losses?


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Problem 13

The hydroelectric turbine, shown in the figure above, passes 8 million gal/min across ahead of 600 ft. What is the maximum amount of power output possible? Why the actualamount be less?

Problem 14

A pump is to move 1000 gallons of water within 10 minutes from a lake into a large,pressurized tank as shown above in the diagram. Will a pump that adds 3 hp to thewater work for the purpose? Support your answer with appropriate calculations.Repeat the calculations if the tank was pressurized to 3, rather than 2, atmospheres.


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CONVERSION FACTORS

1 m = 3.28 ft 1 ft = 0.3048 m

1 KM = 0.6215 Mile 1 Mile = 1.609 KM

1 Kg mass = 2.2 lbm 1 lbm = 0.455 Kg mass

1 m3 = 35.32 ft3 1 ft3 = 2.83110-2 m3

UK Gallon = 4.546 Liters US Gallons = 3.785 Liters

1 N = 0.2248 Lbf 1 Lbf = 4.448 N

Universal Gas Constant = Ru = 8.314103 J/(oK.KgMole) - SI Units

Universal Gas Constant = Ru = 1545.38 ft. Lbf /( 0R.lbmMole) - FPS Units

Universal Gas Constant = Ru = 49.761103 ft. Lbf /( 0R.slugMole) - FPS Units

Specific Gas Constant = Rg = Ru/MWg MWg = Molecular weight of the gas

AIR Properties

MWair = 28.97 Kg/KgMole Rair = 287 J/(oK.Kg) Rair = 1715 ft.lbf /(0R.slug)

air = 1.225 Kg/m3 at 150 C, 101.32 KPa

air = 0.0023769 slugs/ft3 at 590 F, 14.696 lbf / ft2

CONVERSION FACTORS

1 m = 3.28 ft 1 ft = 0.3048 m

1 KM = 0.6215 Mile 1 Mile = 1.609 KM

1 Kg mass = 2.2 lbm 1 lbm = 0.455 Kg mass

1 m3 = 35.32 ft3 1 ft3 = 2.83110-2 m3

UK Gallon = 4.546 Liters US Gallons = 3.785 Liters


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1 N = 0.2248 Lbf 1 Lbf = 4.448 N

Universal Gas Constant = Ru = 8.314103 J/(oK.KgMole) - SI Units

Universal Gas Constant = Ru = 1545.38 ft. Lbf /( 0R.lbmMole) - FPS Units

Universal Gas Constant = Ru = 49.761103 ft. Lbf /( 0R.slugMole) - FPS Units

Specific Gas Constant = Rg = Ru/MWg MWg = Molecular weight of the gas

AIR Properties

MWair = 28.97 Kg/KgMole Rair = 287 J/(oK.Kg) Rair = 1715 ft.lbf /(0R.slug)

air = 1.225 Kg/m3 at 150 C, 101.32 KPa

air = 0.0023769 slugs/ft3 at 590 F, 14.696 lbf / ft2

Assignment Sheet No 2_2016

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