(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

⇐ MCQ in Power Plant Engineering Part 6 | ME Board Exam

**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

Answer: **Option A**

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

Answer: **Option B**

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

Answer: **Option D**

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

Answer: **Option C**

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

Answer: **Option A**

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

Answer: **Option D**

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 m^{3} per kilogram. Assume 85% volumetric efficiency, determine the bore in mm.

A. 400 mm

B. 300 mm

C. 450 mm

D. 500 mm

Answer: **Option A**

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/m^{3}

B. 3565 kg/m^{3}

C. 1255 kg/m^{3}

D. 2550 kg/m^{3}

Answer: **Option B**

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/m^{3}

B. 15.2 N/m^{3}

C. 76.3 N/m^{3}

D. 98.2 N/m^{3}

Answer: **Option B**

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 lb_{f} per cubic foot.)

A. 82.2 kN/m^{3}

B. 102.3 kN/m^{3}

C. 132.9 kN/m^{3}

D. 150.9 kN/m^{3}

Answer: **Option C**

Explanation:

311. If the specific weight of a liquid is 58.5 lb_{f} per cubic foot, what is the specific volume of the liquid in cm^{3}/g?

A. 0.5321 cm^{3}/g

B. 0.6748 cm^{3}/g

C. 0.9504 cm^{3}/g

D. 1.0675 cm^{3}/g

Answer: **Option D**

Explanation:

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

A. Pa

B. bars

C. kg/m-s^{2 }

D. kg/m^{2}

Answer: **Option C**

Explanation:

313. A cylinder weighs 150 lb_{f}. 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

Answer: **Option B**

Explanation:

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

A. 9810 dyne/cm^{2}

B. 9810 N/m^{2}

C. 0.1 bars

D. 0.1 atm

Answer: **Option B**

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/m^{3} 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

Answer: **Option D**

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

Answer: **Option D**

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/s^{2}?

A. 0.680 N

B. 42.5 N

C. 680 N

D. 4250 N

Answer: **Option C**

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/s^{2}. What force is necessary to do this? Assume gravity is 9.81 m/s^{2} and the density of the water is 1 g/cm^{3}.

A. 2.00 N

B. 2.98 N

C. 15.0 N

D. 2.00 kN

Answer: **Option B**

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

Answer: **Option B**

Explanation:

320. A force of 200 lb_{f} 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

Answer: **Option C**

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

Answer: **Option B**

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

Answer: **Option D**

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/m^{2}

B. 285 W/m^{2}

C. 369 W/m^{2}

D. 429 W/m^{2}

Answer: **Option C**

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

Answer: **Option D**

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

Answer: **Option C**

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 lb_{f} weight?

A. 0.09 m/s

B. 0.32 m/s

C. 0.98 m/s

D. 1.52 m/s

Answer: **Option D**

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

Answer: **Option B**

Explanation:

328. Two liters of an ideal gas at a temperature of T_{1} = 25°C and a pressure of P_{1} = 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

Answer: **Option B**

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 10^{3} J-m/s

D. 89.5 kJ

Answer: **Option B**

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

Answer: **Option C**

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

Answer: **Option C**

Explanation:

332. What is the pressure at point A in the tank if h = 2 feet? (g = 32.2 ft/s^{2} and ρ = 1.94 slug/ft^{3})

A. 75 lb_{f}/ft^{2}

B. 85 lb_{f}/ft^{2}

C. 100 lb_{f}/ft^{2}

D. 125 lb_{f}/ft^{2}

Answer: **Option D**

Explanation:

333. Determine the average velocity through a circular section in which the velocity distribution is given by v = v_{max} [1 – (r/r_{0})^{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. v_{max}/4

B. v_{max}/3

C. v_{max}/2

D. v_{max}

Answer: **Option C**

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

Answer: **Option A**

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%

Answer: **Option C**

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 m^{3}/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

Answer: **Option A**

Explanation:

337. A fluid with kinetic viscosity of 2.5 x 10^{-5} ft^{2}/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.

Answer: **Option C**

Explanation:

338. The Reynold’s number of a sphere falling in air is 1 x 10^{6}. If the sphere’s radius is 1 ft., what is its velocity? (ρ = 0.00234 slug/ft^{3}, μ_{air} = 3.8 x 10^{-7} lb_{f}-s /ft^{2}).

A. 2.5 ft/s

B. 5.1 ft/s

C. 40.6 ft/s

D. 81.2 ft/s

Answer: **Option D**

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/ft^{2}

B. 23.78 lbf/ft^{2}

C. 337.26 lbf/in^{2}

D. 337.26 lbf/ft^{2}

Answer: **Option D**

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

Answer: **Option A**

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

Answer: **Option C**

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.

Answer: **Option D**

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.

Answer: **Option C**

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

Answer: **Option A**

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

Answer: **Option A**

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 ft^{3}/hr.

B. 271.6 ft^{3}/hr.

C. 281.8 ft^{3}/hr.

D. 291.6 ft^{3}/hr.

Answer: **Option A**

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

Answer: **Option D**

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

Answer: **Option A**

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

Answer: **Option A**

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 ft^{3}/min.

A. 3.25 ft^{2}

B. 4.25 ft^{2}

C. 5.25 ft^{2}

D. 6.25 ft^{2}

Answer: **Option C**

Explanation:

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