MOMENTUM TRANSFER Flashcards
- Convert 15.14 poises to kinematic viscosity in square feet per second
if the liquid has a specific gravity of 0.964.
a. 0.0169 ft2
/s
b. 0.0258 ft2
/s
c. 0.0333 ft2
/s
d. 0.0421 ft2
/s
a. 0.0169 ft2
/s
- The viscosity of a gas
a. decreases with increase in temperature
b. increases with increase in temperature
c. is independent of temperature
d. is independent of pressure for very high pressure intensities
b. increases with increase in temperature
- A piston of diameter 70.00 mm moves inside a cylinder of diameter
70.10 mm. Determine the percent decrease in force necessary to
move the piston when the lubricant warms from 0 to 1200C. Values
of μ for the lubricant are 0.01820 Pa-s at 00C and 0.00206 Pa-s at
1200C.
a. 72%
b. 89%
c. 63%
d. 55%
b. 89%
- The dimensionless number that characterizes the flows of fluid in a
conduit.
a. Nusselt number
b. Peclet number
c. Grashof number
d. Reynolds number
d. Reynolds number
- Turbulent flow generally occurs for cases involving
a. viscous fluid
b. very narrow passages for capillary tube
c. very slow motions
d. none of these
d. none of these
- Water at 800F at 10 ft/s through a 6 inches sch 40 steel pipe with
length of 1000 ft. The Reynolds number is
a. 330 000
b. 260 000
c. 550 000
d. 830 000
c. 550 000
For numbers 7 to 8:
In an air pipeline, the flow has the following conditions at section 1:
250C, 1.8 bar, 15 m/s velocity, and 50 mm inside diameter of pipe.
At section 2 the conditions are: 250C, 1.3 bar, and 75 mm inside
diameter of pipe.
- Calculate the mass flow rate of air.
a. 0.062 kg/s
b. 0.034 kg/s
c. 0.051 kg/s
d. 0.075 kg/s
- Determine the velocity at the section 2.
a. 6.4 m/s
b. 7.5 m/s
c. 9.2 m/s
d. 3.3 m/s
- a. 0.062 kg/s
- c. 9.2 m/s
- Water flows through an 8 in (ID=7.981 in) steel pipe at an average
velocity of 6 ft/s. Downstream the pipe splits into an 8-in main and a
2 in (ID=2.067 in) bypass pipes. If the velocity in the bypass is twice
the velocity of the main pipe, calculate the volumetric flowrate in the
main pipe in ft3
/s.
a. 1.84
b. 2.31
c. 3.05
d. 4.69
a. 1.84
- Water at 200C enters an inclined 1-inch ID where the upstream point
is at 10 psig. The downstream point is ½ inch ID and 40 ft below the
upstream point where the water discharges at 30 gpm to the
atmosphere. What is the friction in ft of water?
a. 10.2
b. 8.6
c. 28.1
d. 45.2
c. 28.1
- Water at 200C is pumped at a constant rate of 9 m3
/h from a large
reservoir resting on the floor to the open top of an experimental
absorption tower. The point of discharges is 5 m above the floor, and
the frictional losses in the 50 mm pipe from the reservoir to the tower
amount to 2.5 J/kg. At what height in the reservoir must the water
level be kept if the pump can develop only 0.1 kW?
a. 2.50 m
b. 1.26 m
c. 3.84 m
d. 0.77 m
b. 1.26 m
For numbers 12 to 13:
A pump draws 69.1 gal/min of a liquid solution having a density of
114.8 lb/ft3
from an open storage feed tank of large cross sectional
area through a 3-inch sch40 suction line. The pump discharges its
flow through a 2-inch sch40 line to an open overhead tank. The end
of the discharge line is 50 ft above the level of the liquid in the feed
tank. The friction losses in the piping system are 10 ft-lbf/lb.
- What pressure must the pump develop?
a. 35 psi
b. 29 psi
c. 48 psi
d. 10 psi
- What is the horsepower of the pump if the efficiency is 65%? The
flow is turbulent.
a. 3 hp
b. 7 hp
c. 5 hp
d. 2 hp
- c. 48 psi
- a. 3 hp
- For an ideal fluid flow, the Reynolds number is
a. 2100
b. 100
c. zero
d. infinity
d. infinity
- In a nozzle flow, the inlet conditions are P1=365 kPa gage and
D1=100 mm and the outlet conditions are P2=0 kPa gage and D2=50
mm. Find the flow rate and neglect viscous effects. The fluid is water.
a. 0.032 m3
/s
b. 0.055 m3
/s
c. 0.019 m3
/s
d. 0.028 m3
/s
b. 0.055 m3
/s
- In a certain chemical plant, the carbonate solution used in the
absorption tower is pumped continuously from the bottom of the lye
storage tank through a standard 4 in. pipe and then through sprays
head at the top of the scrubber. The depth of solution in the storage
tank is 10 ft and the vertical distance from the spray head to the
bottom of the tank is 110 ft.
In a test on this equipment the following data were obtained:
Rate of flow 200 gpm
Density 68.9 lb/ft3
Friction drop from tank to spray head 15 ft-lbf/lb
Gage pressure on spray head 5 psi
Power input to pump 14 hp
Calculate the efficiency of the pump.
a. 60%
b. 75%
c. 50%
d. 65%
c. 50%
- A water storage tank supplies water into a factory. Water is supplied
to the tank through a booster pump installed in the water line. The
theoretical pump horsepower required is 3.25 hp. What is the
monthly operating cost of the pump, if electrical power cost on the
average is P 3.73/kWh? The pump is 65% efficient and operates for
12 hours a day.
a. P 3300
b. P 7000
c. P 5000
d. P 9000
c. P 5000
- Water is stored in an elevated reservoir. To generate power, water
flows from this reservoir down through a large conduit to a turbine
and then through a similar-sized conduit. At a point in the conduit
89.5 m above the turbine, the pressure is 172.4 kPa, and a level 5 m
below the turbine, the pressure is 89.6 kPa. The water flow rate is
0.800 m3
/s. The output of the shaft of the turbine is 658 kW. The
water density is 1000 kg/m3
. If the efficiency of the turbine in
converting the mechanical energy given up by the fluid to the turbine
shaft is 89 %, calculate the friction loss in the turbine in J/g.
a. 97 J/kg
b. 85 J/kg
c. 81 J/kg
d. 76 J/kg
b. 85 J/kg
For numbers 19 to 21:
A liquid having a density of 801 kg/m3 and a viscosity 1.49x10-3 Pa-
s is flowing through a horizontal straight pipe of a velocity of 4.57
m/s. The commercial steel pipe is 1 ½ in nominal pipe size, schedule 40. For a length of a pipe of 61 m, do as follows:
- Calculate the friction loss.
a. 491 J/kg
b. 350 J/kg
c. 126 J/kg
d. 278 J/kg
- For smooth tube of the same inside diameter, calculate the friction
loss.
a. 410 J/kg
b. 350 J/kg
c. 100 J/kg
d. 280 J/kg
- What is the percent reduction of the F for the smooth tube?
a. 21%
b. 13%
c. 42%
d. 34%
- b. 350 J/kg
- d. 280 J/kg
- a. 21%
For numbers 22 to 23:
A steel pipe having an inside diameter of 13.25 inches is to be
designed to carry 48 000 bbl of oil per 24 hour day from a mid-
continent field to a refinery 580 miles from the source. The difference
in elevation of the two ends of the line is negligible. At an average
temperature involved, the oil has an absolute viscosity of 50
centipoises and a specific gravity of 0.87.
- Calculate the horsepower required to overcome friction in the pipe
line.
a. 5100 hp
b. 1600 hp
c. 3800 hp
d. 4200 hp
- Since the maximum allowable pressure in any section of the line is
650 psi, it will be necessary to insert additional pumping stations at
suitable intervals along the pipe line. What is the smallest number of
pumping stations required?
a. 15
b. 10
c. 7
d. 5
- a. 5100 hp
- b. 10
- What is the hydraulic diameter of a rectangular duct with dimensions
6 inches by 12 inches?
a. 8 inches
b. 10 inches
c. 10.63 inches
d. 11.86 inches
a. 8 inches
- The hydraulic diameter of concentric annular space where 1-in OD
pipe is located inside a 2-in ID pipe is
a. 1 in
b. 1.5 in
c. pi/4 in
d. 2 in
a. 1 in
- Water is flowing at a rate of 80 gpm through 50 ft of an annular
conduit made of ½ in and 1 ¼ in schedule 40 steel pipe. What is the
pressure drop in the 50 ft? Assume as average properties, a density
of 62.3 lb/ft3 and a viscosity of 0.88 centipoise.
a. 110 psia
b. 125 psia
c. 115 psia
d. 150 psia
d. 150 psia
- The pressure after the pump in a 6-inch inside diameter smooth pipe
conducting water is 20 psia. The water is discharged at an open tank
100 ft from the pump. Calculate the rate of discharge of water in ft3
/s.
a. 2.5
b. 5.8
c. 1.6
d. 3.6
d. 3.6
- A pump discharges ethanol at 380C into a smooth tube of 50 mm ID
at a gage pressure of 280 kPa. This pipe is 40 m long (total
equivalent length) and supplies ethanol at a gage pressure of 140
kPa to a reactor. What is the volumetric flow rate of ethanol to the
reactor? There is negligible change in elevation between the pump
and reactor. ρ = 820 kg/m3 and μ = 0.9 cP.
a. 0.01 m3
/s
b. 0.03 m3
/s
c. 0.02 m3
/s
d. 0.04 m3
/s
a. 0.01 m3
/s
- Water flowing at 2.27 m3
/hr at 320 K is pumped through a 40 mm ID
pipe, through a length of 150 m in a horizontal direction, and up
through a vertical height of 10 m. In the pipe there is a control valve,
equivalent to 200 pipe diameters, and other pipe fittings equivalent
to 60 pipe diameters. Also in the line is a heat exchanger across
which the head lost is 1.5 m water. Assume that the main pipe has a
roughness of 0.2 mm What power must be supplied to the pump if it
is 60 percent efficient?
a. 97 W
b. 188 W
c. 136 W
d. 205 W
c. 136 W
For numbers 30 to 31:
A cooling water pump is operating at a speed of 2800 rpm. Its flow
rate is 1000 gal/min at a head of 160 ft.
- What is the power requirement of the pump?
a. 10 kW
b. 30 kW
c. 20 kW
d. 40 kW - If the pump speed is increased to 5000 rpm, determine the new
power requirement.
a. 47 kW
b. 133 kW
c. 80 kW
d. 170 kW
- b. 30 kW
- d. 170 kW
- When a fluid flows through a reducer in a piping system, the velocity
at the outlet end is _ the velocity at the inlet.
a. less than
b. more than
c. the same as
d. one-half
b. more than
- For pipes that must be broken at intervals for maintenance, the
connector used should be a/an
a. union
b. reducer
c. tee
d. elbow
a. union
- Which valve is used accurately to regulate the flow of liquids and
gases at low flow rates?
a. needle valve
b. check valve
c. ball valve
d. globe valve
a. needle valve
- Calculate the radius of capillary tube in mm, such that it is a flow of
a viscous fluid
.
Kinematic viscosity 0.000043 m2
/s
Length of tube 50.2 cm
Mass flow rate 0.003 kg/s
Density of fluid 955 kg/m3
Pressure drop 4.77 atm
a. 0.32
b. 0.18
c. 0.75
d. 0.45
c. 0.75
- Methane at 60 0F is flowing at a steady mass rate through a steel
main having an inside diameter of 12 inches. The absolute pressure
drops from 40 atm to 20 atm, in a length of 500 miles substantially
horizontal pipe. Calculate the hourly rate of flow expressed as ft3
measured at 600F and normal barometric pressure.
a. 650000 cfh
b. 380000 cfh
c. 520000 cfh
d. 440000 cfh
a. 650000 cfh
- Nitrogen gas is flowing through a 4” sch40 steel pipe at 25 0C. The
flow rate is 7.4 x10-2 kg/s and the flow is assumed isothermal. The
pipe is 3000 m long and the inlet pressure is 200 kPa abs. What is
the outlet pressure?
a. 189 kPa
b. 155 kPa
c. 170 kPa
d. 146 kPa
a. 189 kPa
For numbers 38 to 39:
Calculate the theoretical adiabatic horsepower to compress 1000
cfm of helium from standard atmospheric pressure and 800F to 200
psig,
- In a single stage.
a. 308 hp
b. 228 hp
c. 210 hp
d. 546 hp
- In 2 stages.
a. 308 hp
b. 228 hp
c. 210 hp
d. 546 hp
- a. 308 hp
- b. 228 hp
Nitrogen is to be compressed in four stages from 14.7 psia to 3500
psig. What would be the pressure in the third stage?
a. 894 psia
b. 227 psia
c. 753 psia
d. 561 psia
a. 894 psia
- A pitot tube with U-tube water manometer is attached to a horizontal
pipe of 4 in inside diameter. If the manometer reading is 15 in,
determine the volumetric flowrate, in gpm, of oil in the pipe. The pitot
opening is placed at the center of the pipe. The oil has a specific
gravity of 0.84 and a viscosity of 0.0336 lb/ft-s.
a. 77
b. 55
c. 32
d. 94
a. 77
- Which of the following is not true?
a. A pump will operate safely if its NPSH is greater than zero.
b. Fans and blowers are used to transport gases.
c. Pumps and blowers increase the mechanical energy of the fluid.
d. The power loss due to friction in a venturi meter is greater than in
an orifice meter.
d. The power loss due to friction in a venturi meter is greater than in
an orifice meter.