# MCQ in Power Plant Engineering Part 7 | ME Board Exam

(Last Updated On: December 26, 2020) This is the Multiple Choice Questions Part 7 of the Series in Power Plant Engineering as one of the Mechanical Engineering topic. In Preparation for the ME Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Mechanical Engineering field, Mechanical Engineering Books, Journals and other ME References. I assume you are looking for a reviewer that will help you achieve your goal to become a License Mechanical Engineer very soon. Yes, you are in the right place to make your dream come true. Make sure to familiarize each and every questions to increase the chance of passing the Mechanical Board Examination.

#### MCQ Topic Outline included in ME Board Exam Syllabi

• MCQ in Power Plant Elements
• MCQ in Power Plant Design
• MCQ in Industrial Plant Engineering
• MCQ in Industrial Plant Design
• MCQ in Refrigeration Engineering and its Applications
• MCQ in Air Conditioning

#### Continue Practice Exam Test Questions Part 7 of the Series

Choose the letter of the best answer in each questions.

301.  How  many  tons  of  refrigeration  is   required  to  produce  10  metric tons of ice per day at  -10°C from raw water at 22°C if miscellaneous losses are 15% of the chilling and freezing  load?

A. 17 TOR

B. 20 TOR

C. 15 TOR

D. 24 TOR

Explanation:

302.  Five hundred kilograms of poultry enter a chiller at 8°C and are frozen and chilled to a final temperature  of  18°C  for  storage  in  15  hours.  The  specific  heat  above  and  below freezing are 3.18  kJ/kg-°C  and  1.55  kJ/kg -°C  respectively.  The  latent  heat  is  246  kJ/kg  and  the  freezing temperature  is  -5°C. Compute the product  load.

A. 2.75 kW

B. 2.85 kW

C. 2.95 kW

D. 3.15 kW

Explanation:

303.  Fish weighing 11,000 kg with a temperature of 20°C is brought to a cold storage and which shall  be  cooled  to  -10°C  in  11  hours.  Find  the  required  plant refrigerating  capacity  in  tons of refrigeration if the specific heat of fish is 0.7 kCal/kg -°C above freezing point and 0.30 kCal/kg -°C below freezing point. The freezing point is  -3°C. The latent heat of freezing is 55.5 kCal/kg.

A. 25.26 TOR

B. 15.26 TOR

C. 14.38 TOR

D. 24.38 TOR

Explanation:

304.  The  power  requirement  of  a  Carnot  refrigerator  in  maintaining a low temperature region at 300 K is 1.5 kW per ton. Find the heat rejected.

A. 4.02 kW

B. 7.02 kW

C. 5.02 kW

D. 6.02 kW

Explanation:

305.  A  vapor  compression  refrigeration  system  is  designed  to  have  a  capacity  of  150 tons of refrigeration. It produces chilled water from 22°C to 2°C. Its actual coefficient of performance is 5.86  and  35%  of  the  power  supplied  to  the compressor  is  lost  in  the  form  of  friction  and cylinder cooling losses. Determine the condenser cooling water required for a temperature rise of 10°C.

A. 14.75 kg/s

B. 15.65 kg/s

C. 18.65 kg/s

D. 13.75 kg/s

Explanation:

306.  Determine the heat extracted from  2000 kg of water from 25°C to ice at  -10°C.

A. 621,150 kJ

B. 721,150 kJ

C. 821,150 kJ

D. 921,150 kJ

Explanation:

307.  A single acting, twin cylinder, Ammonia compressor with bore equal to stroke  is driven by an  engine  at  250  rpm.  The  machine  is  installed  in  a  chilling  plant  to  produce  700  kW  of refrigeration  at  -18°C  evaporating  temperature.  At  this temperature  the  cooling  effect  per  kg mass is 1160 kJ. The specific volume of vapor entering the compressor is 0.592 m3 per kilogram. Assume 85% volumetric efficiency, determine the bore in mm.

A. 400 mm

B. 300 mm

C. 450 mm

D. 500 mm

Explanation:

308.  An  iron  block weighs 7 Newtons and has a volume of 200 cubic centimeters. What is the density the block?

A. 3465 kg/m3

B. 3565 kg/m3

C. 1255 kg/m3

D. 2550 kg/m3

Explanation:

309. If the density of the gas is 0.003 slugs per cubic foot, what is the specific weight of the gas?

A. 9.04 N/m3

B. 15.2 N/m3

C. 76.3 N/m3

D. 98.2 N/m3

Explanation:

310.  The  specific  gravity  of mercury relative to water is 13.55. What is the specific weight of mercury?  (The specific weight of water is 62.4 lbf per cubic foot.)

A. 82.2 kN/m3

B. 102.3 kN/m3

C. 132.9 kN/m3

D. 150.9 kN/m3

Explanation:

311.  If the specific weight  of a liquid is 58.5 lbf per cubic foot, what is the specific volume of the liquid in cm3/g?

A. 0.5321 cm3/g

B. 0.6748 cm3/g

C. 0.9504 cm3/g

D. 1.0675 cm3/g

Explanation:

312. Which of the following is not a unit of pressure?

A. Pa

B. bars

C. kg/m-s2

D. kg/m2

Explanation:

313.  A  cylinder weighs 150 lbf. Its cross -sectional  area is 40 square inches. When the cylinder stands vertically on one end, what pressure does the cylinder exert on the floor?

A. 14.1 kPa

B. 25.8 kPa

C. 63.2 kPa

D. 89.7 kPa

Explanation:

314. What pressure is a column of water 100 centimeters high equivalent to?

A. 9810 dyne/cm2

B. 9810 N/m2

C. 0.1 bars

D. 0.1 atm

Explanation:

315.  Water is flowing in a pipe with a radius of 10” at a velocity of 5 m/s. At the temperature in the pipe, the density and viscosity of the water are as follows:

ρ = 997.9 kg/m3 and μ = 1.131 Pa-s.

What is the Reynold’s number for this situation?

A. 44.1

B. 88.2

C. 1140

D. 2241

Explanation:

316.  How long must a current of 5.0 amperes pass through a 10 ohm resistor until a charge of 1200 coulombs passes through?

A. 1 min

B. 2 min

C. 3 min

D. 4 min

Explanation:

317.  A car moving at 70 km/hr has a mass of 1700  kg. What force is necessary to decelerate it at a rate of 40 cm/s2?

A. 0.680 N

B. 42.5 N

C. 680 N

D. 4250 N

Explanation:

318.  One  hundred  milliliters  of  water  in  a  plastic  bag  of  negligible  mass  is  to  be  catapulted upwards  with  an initial acceleration of 20.0 m/s2. What force is   necessary to do this? Assume gravity is 9.81 m/s2 and the density of the water is 1 g/cm3.

A. 2.00 N

B. 2.98 N

C. 15.0 N

D. 2.00 kN

Explanation:

319.  A  boy  pulls  a  sled  with  a  mass  of  20  kg  horizontally over a surface with a coefficient of friction of 0.20. It takes him 10 minutes to pull the sled 100 yards. What is his average power output  over these 10 minutes?

A. 4 W

B. 6 W

C. 8 W

D. 10 W

Explanation:

320.  A force of 200 lbf acts on a block at an angle of 28° with respect to horizontal. The block is pushed 2 feet horizontally.  What is the work done by this force?

A. 215 J

B. 320 J

C. 480 J

D. 540 J

Explanation:

321.  Two particles collide, stick together and continue their motion together. Each particle has a  mass  of  10  g  and  their  respective  velocities  before  the collision were 10  m/s and 100  m/s. What is the energy of the system after the collision?

A. 21.8 J

B. 30.2 J

C. 42.8 J

D. 77.9 J

Explanation:

322.  A copper bar is 90 centimeters long at 86°F. What is the increase in its length when the bar is heated to 95°F? The linear expansion coefficient for copper,  α, is 1.7 x 10-5/°C.

A. 2.12 x 10-5 m

B. 3.22 x 10-5 m

C. 5.25 x 10-5 m

D. 7.65 x 10-5 m

Explanation:

323.  Calculate  the  energy  transfer  rate  across  a  6″  wall  of  firebrick  with  a  temperature difference  across  the  wall of 50°C. The thermal conductivity of firebrick is 0.65 BTU/hr -ft-°F at the temperature  of interest.

A. 112 W/m2

B. 285 W/m2

C. 369 W/m2

D. 429 W/m2

Explanation:

324.  A house has brick walls 15 millimeters thick. On a cold winter day, the temperature of the inner and outer layers of the walls  are measured and found to be 20°C and  -12°C, respectively. If there is 120 m2 of exterior wall of race, and the thermal conductivity of bricks is 0.711 J/m-s -°C, how much heat is lost through the walls per hour?

A. 182 J

B. 12.5 kJ

C. 655 kJ

D. 655 MJ

Explanation:

325.  If a    horsepower  pump runs for 20 minutes, what is the energy used?

A. 0.06 ergs

B. 0.25 kW

C. 0.30 MJ

D. 0.11 kW-h

Explanation:

326.  A power of 6 kW is supplied to the motor of a crane. The motor has  an efficiency of 90%. With what constant speed does the crane lift the 800 lbf weight?

A. 0.09 m/s

B. 0.32 m/s

C. 0.98 m/s

D. 1.52 m/s

Explanation:

327.  An engine has an  efficiency of 26%. It uses 2 gallons of gasoline per hour. Gasoline has a heating value of 20,500 BTU/lbm  and a specific gravity of 0.8. What is the power output of the engine?

A. 0.33 kW

B. 20.8 kW

C. 26.0 kW

D. 41.7 kW

Explanation:

328.  Two liters of an ideal gas at a temperature of T1 = 25°C and a pressure of P1 = 0.101 MPa, are in a 10 cm diameter cylinder with a piston at one end. The piston is depressed so that the cylinder is shortened by 10 centimeters.  The temperature increases by 2°C. What is the change in pressure?

A. 0.156 MPa

B. 0.167 MPa

C. 0.251 MPa

D. 0.327 MPa

Explanation:

329.  The average power output  of a cylinder in a combustion engine is given by:

P̅ = pLAN

where:

p = average pressure on the piston during the stroke

L = length of the piston stroke

A = area of the piston head

N = number  of strokes per second

An 8-ylinder engine has the following specifications

p = 283 kPa

L = 14 cm

d = diameter  of piston head = 12 cm

N = 1500 strokes/min

What is the average power output  of this engine?

A. 89.5 N/s

B. 89.5 kW

C. 89.5 x 103 J-m/s

D. 89.5 kJ

Explanation:

330.  What is the power required to transfer 97,000 coulombs of charge through a potential rise of 50 volts in one hour?

A. 0.5 kW

B. 0.9 kW

C. 1.3 kW

D. 2.8 kW

Explanation:

331.  A  current of 7 amperes passes through a 12 ohm resistor. What is the power dissipated in the resistor?

A. 84 w

B. 0.59 hp

C. 0.79 hp

D. 7 hp

Explanation:

332. What is the pressure at point A in the tank if h =  2 feet? (g = 32.2 ft/s2 and ρ = 1.94 slug/ft3)

A. 75 lbf/ft2

B. 85 lbf/ft2

C. 100 lbf/ft2

D. 125 lbf/ft2

Explanation:

333.  Determine the average velocity through a circular  section in which the velocity distribution is  given  by v = vmax [1 – (r/r0)2]. The distribution is symmetric with respect to the longitudinal axis, r = 0, ro is the outer radius, vmax  is the velocity along the longitudinal axis.   Assume flow is laminar.

A. vmax/4

B. vmax/3

C. vmax/2

D. vmax

Explanation:

334.  A  pipe  has  a  diameter 4” at section AA,  and a diameter of 2” at section BB. For an ideal fluid flow, the velocity given is 1 ft/s  at section AA. What is the flow velocity at section BB?

A. 4 ft/s

B. 0.5 ft/s

C. 1.0 ft/s

D. 2.0 ft/s

Explanation:

335. A mixing tank mixes two inlet streams containing salt. The salt concentration in stream 1 is 5% by weight, at stream 2 it is 15% by weight. Stream 1 flows at 25 kg/s, and stream 2 flows at 10 kg/s. There is only one exit  stream. Find the salt concentration in the exit stream.

A. 5%

B. 8%

C. 11%

D. 13%

Explanation:

336. Water is pumped at 1 m3/s to an elevation 5 meters  through a flexible hose using a 100% efficient pump rated at 100 kilowatts. Using the same length of hose, what size motor is needed to  pump  1  m3/s  of  water  to  the  tank,  with  no elevation gain? In both cases ,  both ends of  the hose are at the same temperature  and  pressure. Neglect kinetic energy effects.

A. 51 kW

B. 22 kW

C. 36 kW

D. 43 kW

Explanation:

337.  A  fluid  with  kinetic  viscosity  of  2.5  x 10-5 ft2/s   is flowing at 0.1 ft./s   from an orifice 3” in diameter. How can the fluid be described?

A. The fluid is completely turbulent.

B. The fluid is in transition zone.

C. The fluid is laminar.

D. Turbulent cannot be calculated, it must be measured.

Explanation:

338. The Reynold’s number of a sphere falling  in air is 1 x 106. If the sphere’s radius is 1 ft., what is its velocity? (ρ  = 0.00234 slug/ft3, μair = 3.8 x 10-7 lbf-s /ft2).

A. 2.5 ft/s

B. 5.1 ft/s

C. 40.6 ft/s

D. 81.2 ft/s

Explanation:

339. The flow rate of water through a cast iron is 5000 gallons per minute. The diameter of the pipe is 1 foot, and the coefficient of friction is f = 0.0173. What is the pressure drop over a 100 foot length of pipe?

A. 21.078 lbf/ft2

B. 23.78 lbf/ft2

C. 337.26 lbf/in2

D. 337.26 lbf/ft2

Explanation:

340. A cylindrical flash tank mounted with its axis horizontal is used to separate liquid ammonia from  ammonia  vapor.   The  ammonia  bubbles  through  the  liquid  with  70  m3/min  leaving  the disengaging  surface.  The  disengaging  rate  is  limited  to  60  m/min  and  the  liquid  level  is  to operate with the liquid level one-third to the diameter from the top. Determine the diameter if the tank is 1.5  m long.

A. 830 mm

B. 730 mm

C. 860 mm

D. 760 mm

Explanation:

341.  A 150 Hp motor  is used to drive the compressor. If the heat loss from the compressor is 25 kW  and  the  mass  flow  rate of the refrigerant entering the compressor is 0.50 kg/s, determine the difference of the enthalpies between the inlet and outlet of the compressor.

A. 143.80 kJ/kg

B. 153.80 kJ/kg

C. 173.80 kJ/kg

D. 183.80 kJ/kg

Explanation:

342.  To cool farm products, 300 kg of ice at  -4.4°C are placed in bunker. Twenty four hours later the ice has melted into water at 7.2°C. What is the average rate of cooling provided by the ice in kJ/hr?

A. 2679.28 kJ/hr.

B. 5679.28 kJ/hr.

C. 3679.28 kJ/hr.

D. 4679.28 kJ/hr.

Explanation:

343.  Determine  the  estimated  condenser  load  for  an  open -type  compressor  having  a  cooling capacity of 16,500 Btu/hr and a heat rejection factor of 1.32.

A. 22,280 Btu/hr.

B. 20,780 Btu/hr.

C. 21,780 Btu/hr.

D. 19,780 Btu/hr.

Explanation:

344.  If  the  load  on  water-cooled  condenser  is  150,000 Btu/hr. and the temperature rise of the water in the condenser is 10°F, what is the quantity of water circulated in gpm?

A. 30 GPM

B. 40 GPM

C. 20 GPM

D. 50 GPM

Explanation:

345.  The  load on a water-cooled condenser is 90,000 Btu/hr. if the quantity of water circulated through  the  condenser  is  15  gpm,  determine  the  temperature  rise  of  the  water  in  the condenser.

A. 12°F

B. 14°F

C. 16°F

D. 18°F

Explanation:

346.  The  weight  of  ammonia  circulated  in  a  machine  is  found  to  be  21.8  lb/hr.  if  the  vapor enters  the  compressor  with  a  specific  volume  of  9.6 ft3/lb, calculate the piston displacement, assuming 80% percent volume efficiency.

A. 261.6 ft3/hr.

B. 271.6 ft3/hr.

C. 281.8 ft3/hr.

D. 291.6 ft3/hr.

Explanation:

347.  A  single-stage  ammonia  compressor  is  producing  10  tons  of refrigeration and the power consumed  is  15  Hp.  Suction  pressure  is  25  psi,  condensing  pressure  is  180  psi.  Brine temperature  is 20°F off brine cooler. Determine the actual coefficient of performance.

A. 10.14

B. 11.14

C. 12.14

D. 13.14

Explanation:

348.  In  an  ammonia  condensing  machine  (compressor  plus  condenser)  the  water  used  for condensing is 55°F and the evaporator  is at 15°F. Calculate the ideal COP.

A. 11.875

B. 12.875

C. 10.875

D. 13.875

Explanation:

349.  How much  refrigeration capacity is required to cool 2000 cfm of air from 85°F to 70°F?

A. 2.7 TOR

B. 3.7 TOR

C. 1.7 TOR

D. 4.7 TOR

Explanation:

350.  Determine the coil face area required to maintain a face velocity 400 ft./min if the air flow rate over the coil is 2100 ft3/min.

A. 3.25 ft2

B. 4.25 ft2

C. 5.25 ft2

D. 6.25 ft2

Explanation:

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