This is the Multiple Choice Questions Part 9 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 9 of the Series

โ MCQ in Power Plant Engineering Part 8 | ME Board Exam

**Choose the letter of the best answer in each questions.**

401. The water velocity of a 5 m x 1 m channel is 6 m/s. What is the annual energy produced if the net head is 120 m and the over-all efficiency is 80%?

A. 494,247,258 kW-hrs

B. 247,497,582 kW-hrs

C. 247,494,528 kW-hrs

D. 472,497,582 kW-hrs

Answer: **Option C**

Explanation:

402. A hydro-electric impulse turbine is directly coupled to a 24 pole, 60 Hz alternator. It has a specific speed of 60 rpm and develops 3000 Hp. What is the required diameter assuming a peripheral speed ratio of 0.45?

A. 0.661 m

B. 0.552 m

C. 0.443 m

D. 0.773 m

Answer: **Option A**

Explanation:

403. In a hydroelectric power plant the tailwater elevation is at 500 m. What is the head water elevation if the net head is 30 m and the head loss is 5% of the gross head?

A. 785.25 m

B. 582.57 m

C. 528.57 m

D. 758.25 m

Answer: **Option C**

Explanation:

404. The tailwater and headwater of a hydro-electric plant are 150 m and 200 m respectively. What is the water power if the flow is 15 m^{3}/s and a head loss of 10% of the gross head?

A. 6,621.75 kW

B. 7,621.65 kW

C. 5,621.76 kW

D. 4,621.56 kW

Answer: **Option A**

Explanation:

405. In a hydro-electric plant, water flows at 10 m/s in a penstock of 1 m^{3} cross-sectional area. If the net head of the plant is 30 m and the turbine efficiency is 85%, what is the turbine output?

A. 2,501.55 kW

B. 2,100.21 kW

C. 3,626.34 kW

D. 3,124.65 kW

Answer: **Option A**

Explanation:

406. A 75 MW power plant has an average load of 35,000 kW and a load factor of 65%. Find the reserve over peak.

A. 21.15 MW

B. 23.41 MW

C. 25.38 MW

D. 18.75 MW

Answer: **Option A**

Explanation:

407. A power plant is said to have/had a use factor of 48.5% and a capacity factor of 42.4%. How many hrs. did it operate during the year?

A. 6,600.32 hrs

B.7,658.23 hrs

C. 8,600.32 hrs

D. 5,658.23 hrs

Answer: **Option B**

Explanation:

408. A 50,000 kW steam plant delivers an annual output of 238,000,000 kW-hr with a peak load of 42,860 kW. What is the annual load factor and capacity factor?

A. 0.634, 0.534

B. 0.643, 0.534

C. 0.634, 0.543

D. 0.643, 0.534

Answer: **Option C**

Explanation:

409. Calculate the use factor of a power plant if the capacity factor is 35% and it operates 8000 hrs. during the year?

A. 38.325%

B. 33.825%

C. 35.823%

D. 32.538%

Answer: **Option A**

Explanation:

410. If the air required for combustion is 20 kg per kg of coal and the boiler uses 3000 kg of coal per hr, determine the mass of gas entering the chimney. Assume an ash loss of 15%.

A. 40,664 kg/hr.

B. 70,200 kg/hr.

C. 62,550 kg/hr.

D. 50,500 kg/hr.

Answer: **Option C**

Explanation:

411. A 15 kg gas enters a chimney at 10 m/s. If the temperature and pressure of a gas are 26ยฐC and 100 kPa respectively, what is the diameter of the chimney? Use R = 0.287 kJ/kg-K.

A. 1.57 m

B. 2.65 m

C. 2.22 m

D. 1.28 m

Answer: **Option D**

Explanation:

412. A two-stage air compressor at 90 kPa and 20ยฐC discharges at 700 kPa. Find the polytropic exponent n if the intercooler intake temperature is 100ยฐC.

A. 1.29

B. 1.33

C. 1.4

D. 1.25

Answer: **Option A**

Explanation:

413. A two-stage compressor receives 0.35 kg/s of air at 100 kPa and 269 K and delivers it at 5000 kPa. Find the heat transferred in the intercooler.

A. 70.49 kW

B. 80.49 kW

C. 90.49 kW

D. 100.49 kW

Answer: **Option A**

Explanation:

414. A centrifugal pump discharged 20 L/s against a head of 17 m when the speed is 1500 rpm. The diameter of the impeller was 30 cm and the brake horsepower was 6.0. A geometrically similar pump 40 cm in diameter is to run at 1750 rpm. Assuming equal efficiencies, what brake horsepower is required?

A. 51.55 HP

B. 50.15 HP

C. 40.14 HP

D. 45.15 HP

Answer: **Option C**

Explanation:

415. A pump delivers 20 cfm of water having a density of 62 lb./ft^{3}. The suction and discharge gage reads 5 in. Hg vacuum and 30 psi respectively. The discharge gage is 5 ft. above the suction gage. If pump efficiency is 70%, what is the motor power?

A. 5.31 HP

B. 3.31 HP

C. 4.31 HP

D. 6.31 HP

Answer: **Option C**

Explanation:

416. Calculate the air power of a fan that delivers 1200 m^{3}/min of air through a 1 m x 1.5 m outlet. Static pressure is 120 mm WG and density of air is 1.18.

A. 20.45 kW

B. 25.64 kW

C. 30.45 kW

D. 35.64 kW

Answer: **Option B**

Explanation:

417. Determine the temperature for which a thermometer with degrees Fahrenheit is numerically twice the reading of the temperature in degrees Celsius.

A. -24.6

B. 320

C. 160

D. -12.3

Answer: **Option C**

Explanation:

418. During takeoff in a spaceship, an astronaut is subjected to acceleration equal to 5 times the pull of the earthโs standard gravity. If the astronaut is 180 lb_{m} and the takeoff is vertical, what force does he exert on the seat?

A. 4810.9 N

B. 4414.5 N

C. 8829 N

D. 9620 N

Answer: **Option A**

Explanation:

419. A pressure cooker operates by cooking food at a higher pressure and temperature possible at atmospheric conditions. Steam is contained in the sealed pot, with vent hole in the middle of the cover, allowing steam to escape. The pressure is regulated by covering the vent hole with a small weight, which is displaced slightly by escaping steam. Atmospheric pressure is 100 kPa, the vent hole area is 7-mm2, and the pressure inside should be 250 kPa. What is the mass of the weight?

A. 0.107 kg

B. 1.05 kg

C. 1.75 kg

D. 0.1783 kg

Answer: **Option A**

Explanation:

420. A barometer can be used to measure an airplaneโs altitude by comparing the barometric pressure at a given flying altitude to that on the ground. Determine an airplaneโs altitude if the pilot measures the barometric pressure at 700 mm-Hg, the ground reports it at 758 mm-Hg, and the average air density is 1.19 kg/m^{3}, g = 9.81 m/s^{2}.

A. 636 m

B. 633 m

C. 366 m

D. 663 m

Answer: **Option D**

Explanation:

421. A mixture of 0.4 lb_{m} of helium and 0.2 lb_{m} of oxygen is compressed polytropically from 14.7 psia and 60ยฐF to 60 psia according to n = 1.4. Determine the final temperature, T_{2}.

A. 727.7ยฐR

B. 777.2ยฐR

C. 722.7ยฐR

D. 277.7ยฐR

Answer: **Option B**

Explanation:

422. A mixture of 0.4 lb_{m} of helium and 0.2 lb_{m} of oxygen is compressed polytropically from 14.7 psia and 60oF t0 60 psia according to n = 1.4. Determine the polytropic work.

A. 139 Btu

B. 239 Btu

C. 339 Btu

D. 539 Btu

Answer: **Option A**

Explanation:

423. A pump in a municipalityโs water-supply system receives water from the filtration beds and pumps it up to the top of a water tower. The towerโs height is 35 m, and the inlet piping to the pump is 2 m below the pumpโs intake. The water temperature is 20 C, measured at both the inlet and the discharge from the pump. The mass flow rate through the pump is 100 kg/s, the diameter of the inlet piping is 25 cm, and the diameter of the discharge piping is 15 cm. Determine the power required by the pump.

A. 77.3 kW

B. 33.77 kW

C. 34.42 kW

D. 42.34 kW

Answer: **Option B**

Explanation:

424. An adiabatic tank containing air is used to power an air turbine during times of peak power demand. The tank has a volume of 500 m3 and contains air at 1000 kPa and 500 K. Determine the mass remaining when the pressure reaches 100 kPa.

A. 273.37 kg

B. 672.73 kg

C. 772.73 k

D. 227.73 kg

Answer: **Option B**

Explanation:

425. Determine the air-fuel ratio on a molar basis for the complete combustion of octane, with theoretical amount of air.

A. 95.5 kg_{air}/kg_{fuel }

B. 59.9 kg_{air}/kg_{fuel}

C.59.5 kg_{air}/kg_{fuel}

D. 55.9 kg_{air}/kg_{fuel}

Answer: **Option C**

Explanation:

426. During a steady state operation, a gearbox receives 60 kW throughout the input shaft and delivers power through the output shaft. For the gearbox as the system, the rate of energy transfer is by convection, h = 0.171 kW/m^{2}-K is the heat transfer coefficient, A = 1.0 m^{2} is the outer surface area of the gearbox, T_{b} = 300 K (27ยฐC) is the temperature at the outer surface, T_{f} = 293 K (20ยฐC) is the temperature of the surroundings away from the immediate vicinity of the 130 gearbox. Determine the power delivered to the output shaft in kW if the heat transfer rate is -1.2 kW.

A. 98.8 kW

B. 78.8 kW

C. 68.8 kW

D. 58.8 kW

Answer: **Option D**

Explanation:

427. A single acting air compressor with a clearance of 6% takes in air at atmospheric pressure and temperature of 85ยฐF and discharges it at a pressure of 85 psia. The air handled is 0.25 ft^{3}/cycle measured at discharge pressure. If the compression is isentropic, find the piston displacement per cycle, if the compressor is running at 750 rpm.

A. 0.0750 ft^{3}/cycle

B. 0.025 ft^{3}/cycle

C. 1.030 ft^{3}/cycle

D. 1.090 ft^{3}/cycle

Answer: **Option C**

Explanation:

428. A single acting air compressor with a clearance of 6% takes in air at atmospheric pressure and temperature of 85ยฐF and discharges it at a pressure of 85 psia. The air handled is 0.25 ft^{3}/cycle measured at discharge pressure. If the compression is isentropic, find the air hp of the compressor if rpm is 750.

A. 16 hp

B. 96 hp

C. 69 hp

D. 61 hp

Answer: **Option B**

Explanation:

429. A nozzle receives 0.5 kg/s of air at a pressure of 2700 kPa and a velocity of 30 m/s and with an enthalpy of 923 kJ/kg, and the air leaves at a pressure of 700 kPa and with an enthalpy of 660 kJ/kg. Determine the exit velocity from the nozzle.

A. 923 m/s

B. 726 m/s

C. 700 m/s

D. 660 m/s

Answer: **Option B**

Explanation:

430. A two-stage, double acting compressor is to deliver 90 lb/min of air from 14.3 psia to 90ยฐF to a final pressure of 185 psia. The normal barometer is 29.8 in-Hg and the temperature is 80ยฐF. The pressure drop in the intercooler is 3 psi and the speed is 210 rpm and pV^{1.34} = C during compression and expansion. The clearance is 5% for both cylinders. Find the volume of free air if the temperature of the cooling water increased by 18ยฐF.

A. 1282 CFM

B. 1230 CFM

C. 1320 CFM

D. 1822 CFM

Answer: **Option B**

Explanation:

431. Consider 4800 lb. of steam per hour flowing through a pipe at 100 psia pressure. Assume a velocity of 5280 ft./min. What size of pipe is required? Specific volume of steam at 100 psia ฯ
= 4.432 ft^{3}/lb.

A. 3 in

B. 5 in

C. 4 in

D. 6 in

Answer: **Option C**

Explanation:

432. A boiler plant generates 225,000 lb. of steam and burns 13.9 tons of coal per hour. The coal has a heating value of 11,400 Btu/lb. A test of the particulates leaving the boiler shows that 3804 lb. of particulate is being discharged per hour. What is the particulate discharged per million Btu heat input to the furnace?

A. 12 lb/10^{6} Btu

B. 14 lb/10^{6} Btu

C. 15 lb/10^{6} Btu

D. 16 lb/10^{6} Btu

Answer: **Option A**

Explanation:

433. A turbine receives 150 lbm/s of air at 63 psia and 2450ยฐR and expands it polytropically to 14.7 psia. The exponent n is equal to 1.45 for the process. Determine the power.

A. 52,343.16 BTU/s

B. 52,343.16 kW

C. 53.343.16 HP

D. 53,343.16 ft-lb/s

Answer: **Option A**

Explanation:

434. Find the thrust and efficiency of two 2-m diameter propellers through which flows a total of 600 m^{3}/s of air to 11.3 N/m^{3}. The propellers are attached to an airplane moving at 250 kph through still air. Neglect eddy losses.

A. 36,077 N, 73%

B. 77,630 N, 37%

C. 66,033 N, 33%

D. 77,330 N, 77%

Answer: **Option A**

Explanation:

435. A liquid with a specific gravity of 1.26 is being pumped in a pipeline from A to B. At A, the pipe diameter is 60 cm and the pressure is 300 kN/m^{2}. At B, the pipe diameter is 30 cm and the pressure is 330 kN/m^{2}. Point B is 1.0 m lower than A. Find the flow rate if the pump puts 16 kW into the flow. Neglect head loss.

A. 4.2 m^{3}/s

B. 0.42 m^{3}/s

C. 2.4 m^{3}/s

D. 0.24 m^{3}/s

Answer: **Option B**

Explanation:

436. A reciprocating compressor handles 1,400 cfm of air measured at intake where P1 = 18 psia and T1 = 90ยฐF. The discharge pressure is 92 psia. Calculate the work if the process of the compression is isothermal.

A. -180.5 hp

B. -179.5 hp

C. -227.6 hp

D. -228.6 hp

Answer: **Option B**

Explanation:

437. The fuel oil has the ff. analysis:

C = 89%ย ย N2 = 2%ย ย H2 = 8%ย ย S = 1%

With 3% excess air, what is the actual amount of air needed to burn the fuel oil?

A. 13.17 kg_{air}/kg_{fuel}

B. 13.47 kg_{air}/kg_{fuel}

C. 14.47 kg_{air}/kg_{fuel}

D. 14.17 kg_{air}/kg_{fuel}

Answer: **Option D**

Explanation:

438. A pump discharges 550 gpm of water to a height of 35 ft. With an efficiency of 80%, what is the power input?

A. 6.09 hp

B. 6.32 hp

C. 4.74 hp

D. 4.94 hp

Answer: **Option A**

Explanation:

439. A room contains air at 20ยฐC and 96 kPa at a relative humidity of 75%. Determine the enthalpy of moist air.

where:

(P_{sat} @ 20ยฐC = 2.339 kPa)

(h_{g} @ 20ยฐC = 2538.1 kJ/kgda)

Given:

Unsaturated air (0% < ร <100%)

t_{d} = 20ยฐC

P_{t} = 96 kPa

ร = 75%

A. 45.919 kJ/kg_{da }

B. 45.515 kJ/kg_{da}

C. 49.515 kJ/kg_{da}

D. 41.815 kJ/kg_{da}

Answer: **Option C**

Explanation:

440. A piston moves inside a cylinder at a velocity of 6.0 m/s. The 160 mm diameter piston is centrally located within the 160.2 mm inside diameter cylinder. The film of oil is separating the piston from the cylinder has an absolute viscosity of 0.4 N-s/m^{2}. Assuming a linear velocity profile, find the shear stress in the oil. (T = ฮผ (v/H))

Given:

ฮผ = 0.40 N-s/m^{2}

v = 5 m/s

H = thickness of oil film = 160.2 โ 160/2 = 0.1 mm

A. 50,000 N/m^{2 }

B. 40,000 N/m^{2}

C. 24,000 N/m^{2}

D. 34,000 N/m^{2}

Answer: **Option C**

Explanation:

441. A centrifugal pump with a 3 ft. impeller diameter operates at 800 rpm. If the speed is to be increased to 1200 rpm, determine the impeller diameter that should be used so that the same shaft input power would be required.

A. 5.32 ft.

B. 2.35 ft.

C. 5.23 ft.

D. 2.93 ft.

Answer: **Option B**

Explanation:

442. Determine the mass of water vapor contained in a 150 m^{3} room at 100 kPa, 23ยฐC and 40% relative humidity. From Steam Tables: P_{sat} @ 23ยฐC = 2.810 kPa.

A. 1.6342 kg

B. 1.9342 kg

C. 1.2342 kg

D. 2.2342 kg

Answer: **Option C**

Explanation:

443. What is the power of the pump, HP, if it delivers 925 gal/min of water against a head of 15 m?

A. 15.38 HP

B. 16.38 HP

C. 10.5 HP

D. 11.5 HP

Answer: **Option D**

Explanation:

444. Kerosene is pumped into an aircraft fuel tank through a hose that has an inside diameter of 4 cm. If the velocity of the kerosene is 8 m/s through the hose, determine the mass flow rate. Assume that the kerosene has a density of 800 kg/mยณ.

A. 7.06 kg/s

B. 7.56 kg/s

C. 8.06 kg/s

D. 8.56 kg/s

Answer: **Option C**

Explanation:

445. During the working stroke of an engine the heat transferred out of the system was 150 kJ/kg of working substance. The internal energy also decreased by 400 kJ/kg of working substance. Determine the work done.

A. 250 kJ/kg

B. 550 kJ/kg

C. 600 kJ/kg

D. 350 kJ/kg

Answer: **Option A**

Explanation:

446. During the experiment on Charles Law, the volume of the gas trapped in the apparatus is 10000 mmยณ when the temperature is 18ยฐC. The temperature of the gas was then raised to 85ยฐC. Determine the new volume of the gas trapped in the apparatus if the pressure exerted on the gas remained constant.

A. 12302.41 mmยณ

B. 8128.49 mmยณ

C. 70833.33 mmยณ

D. 2117.64 mmยณ

Answer: **Option A**

Explanation:

447. Find the density of oil with a specific gravity of 1.6 in-g/cm^{3}.

A. 15.68 g/cm^{3}

B. 99.84 g/cm^{3}

C. 0.8 g/cm^{3}

D. 1.6 g/cm^{3}

Answer: **Option D**

Explanation:

448. What is the absolute pressure if the gauge pressure reading is 9 bar and the atmospheric pressure is 0.9 bar?

A. 6.3 bar

B. 7.8 bar

C. 9.9 bar

D. 8.1 bar

Answer: **Option C**

Explanation:

449. The tank of an air compressor has a volume of 3 ft^{3} and is filled with air at a temperature of 40ยฐF. If a gage on the tank reads 150 psig, what is the mass of the air in the tank?

A. 1.78 lbs.

B. 2.00 lbs.

C. 2.67 lbs.

D. 1.98 lbs.

Answer: **Option C**

Explanation:

450. What is the mass of acetylene gas, V = 0.94 cu. ft., R = 59.35 ft-lb/lb-ยฐR, T = 90ยฐF, P = 200 psia?

A. 0.816 lb.

B. 0.841 lb.

C. 0.829 lb.

D. 0.852 lb.

Answer: **Option C**

Explanation:

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