# MCQ in Power Plant Engineering Part 10 | ME Board Exam

(Last Updated On: December 24, 2020) This is the Multiple Choice Questions Part 10 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 10 of the Series

Choose the letter of the best answer in each questions.

451.  Specific volume is the number of cubic meters of mixture per kilogram of dry air. If dry air has these following properties: Ra = 287 J/kg-K, T = 303 K, Pa = 99.604 kPa. Solve for the specific volume.

A. 0.873 m3/kg

B. 0.853 m3/kg

C. 0.953 m3/kg

D. 0.783 m3/kg

Explanation:

452.  A  refrigerating  system  operates  on the reversed Carnot Cycle. The higher temperature of the  refrigerant  in  the  system  is  120°F  and  the  lower  is 10°F. The capacity is 20 tons. Neglect losses. Determine the coefficient of performance.

A. 2.732

B. 5.373

C. 7.372

D. 4.273

Explanation:

453.  At  a  pressure  of  60°F,  a  motorbike Ire is inflated to 33 psig. As it is driven along the C -5 road,  the  temperature  rose  to  76°F.  Assuming  the  volume  remains  constant,  determine  the final gauge pressure.

Given:

P1 = 33 psig + 14.7 psig = 47.7 psig

T1 = 60°F + 460 = 520°R

T2 = 76°F + 460 = 536°R

A. 34.47 psig

B. 49.17 psig

C. 35.00 psig

D. 34.30 psig

Explanation:

454.  Steam enters a turbine stage with an enthalpy of 3700 kJ/kg and a velocity of 80 m/s and leaves  with  an  enthalpy  of  2864  kJ/kg  with  a velocity of 12.8 m/s. If the rate of a steam flow through  the turbine  is 0.44 kg/s, what is the work  done in kW?

A. 365 kW

B. 365.64 kW

C. 366.0 kW

D. 366.50 kW

Explanation:

455.  Aluminum  has  a  specific  heat  of  0.902  J/g -°C.  How  much  heat  is  lost  when  a  piece  of aluminum  with  a  mass  of  23.984  g  cools  from  a  temperature  of  415.0°C  to  a  temperature  of 22.0°C?

A. 8500 J

B. 6000 J

C. 80000 J

D. 7500 J

Explanation:

456.  If  the  temperature  of  an  air  parcel is  -20.5°C, and its density is 0.690 kg/m3, what is the pressure of the air parcel?

A. 40 kPa

B. 50 kPa

C. 60 kPa

D. 70 kPa

Explanation:

457.  A 35.0 mL sample of gas is enclosed in a flask at 22 degrees Celsius. If the flask was placed in an ice bath at 0 degrees Celsius,  what would the new gas volume be if the pressure is held constant?

A. 34.1 mL

B. 32.1 mL

C. 32.39 mL

D. 33.1 mL

Explanation:

458.  A car engine with a power output of 65 hp has a thermal efficiency of 24%. Determine the fuel consumption  rate of this car if the fuel has a heating value of 19,000 Btu/lb m.

A. 36.28 lbm/hr

B. 37.28 lbm/hr

C. 37.28 lbm/hr

D. 35.30 lbm/hr

Explanation:

459.  The thermal efficiency of a Carnot cycle operating between 170°C and 620°C is closest to:

A. 44%

B. 50%

C. 63%

D. 73%

Explanation:

460.  Compute the humidity ratio of air at 70% relative humidity and 25°C when the barometric pressure is 101.325 kPa. From the steam tables: Psat @ 34 °C  = 3.169 kPa.

A. 0.014 kgwater vapor/kgdry air

B. 0.14 kgwater vapor/kgdry air

C. 1.4 kgwater vapor/kgdry air

D. 0.0014 kgwater vapor/kgdry air

Explanation:

461.  A pressure gauge registers 50 psig in a region where the barometer reads 14.8 psia. Find the absolute pressure in kPa.

A. 666.66 kPa

B. 556.66 kPa

C. 446.66 kPa

D. 336.66 kPa

Explanation:

462.  Consider 1 kg of air at 32°C that expanded by a reversible polytropic process with n = 1.25 until  the  pressure  is  halved. Determine  the heat transfer. Specific heat at constant volume for air is 0.1786 kJ/kg-K.

A. 17.02 kJ heat rejected

B. 7.05 kJ heat rejected

Explanation:

463.  A Carnot cycle uses nitrogen (k = 1.399) as the working substance. The heat supplied is 54 kJ and the adiabatic  expansion ratio is 10. Determine the heat rejected.

A. 10 kJ

B. 32.4 kJ

C. 21.6 kJ

D. 54 kJ

Explanation:

464.  A  tank  contains  20  kg  of  air  at  200 kPa (gage) and 23°C. During the heating process the temperature  of  air  rises.  For  safety  purposes  a  technician  installed a relief -type valve so that pressure of air inside the tank never exceeds 260 kPa (gage). At what air temperature the relief valve will start releasing air?

A. 112°C

B. 92°C

C. 82°C

D. 102°C

Explanation:

465.  An air compressor takes in 9 kg/min of air at 98 kPa; υ1 = 0.125 m3/kg and discharges it at 680 kPa; υ2 = 0.03 m3/kg. The increase of internal energy is 93 kJ/kg and the work done on air is 163  kJ/kg;  the  change  in  potential  and  kinetic  energy  are  neglected.  How  much  heat  is transferred per kg of air?

A. 264.15 kJ/kg

B. 61.85 kJ/kg

C. 288.65 kJ/kg

D. 78.15 kJ/kg

Explanation:

466.  During a reversible process, there are abstracted 317 kJ/s from 1.134 kg/s of a certain gas while the temperature remains constant at 26.7°C. For this gas cp = 2.232 and cv = 1.713 kJ/kg-K. The initial pressure is 586 kPa. Determine the final volume flow rate.

A. 0.301 m3/s

B. 0.03 m3/s

C. 0.5 m3/s

D. 0.05 m3/s

Explanation:

467.  Flow  of  water  in  a  pipe  has  a  velocity  at  10  meters  per  second.  Determine  the  velocity head of the water.

A. 50.1 meters

B. 5.10 meters

C. 8.20 meters

D. 100 meters

Explanation:

468.  A  Diesel  cycle  has  a  cut-off  ratio  of  2.20  and  a  compression  ratio  of  10.  Find  the  cycle efficiency.

A. 55.10%

B. 59.735%

C. 52.23%

D. 62.37%

Explanation:

469.  A  diesel  cycle  has  an  initial  temperature  of  27°C.  If  the  cut-off  ratio  is  2.50  and compression ratio is 12,  find the maximum cycle temperature.

A. 1634.4°C

B. 1753.44°C

C. 2010.3°C

D. 1983.4°C

Explanation:

470. A diesel cycle, which takes in air at 1 bar and 26°C, has a compression ratio of 19. Calculate the operating clearance in percent.

A. 8.08

B. 8.56

C. 7.52

D. 5.55

Explanation:

471.  An  Otto  cycle  has  an  initial  pressure  of  100 kPa  and  has  a  pressure  of  400 kPa  after adiabatic compression. Find the cycle efficiency.

A. 32.70%

B. 34.70%

C. 36.70%

D. 38.70%

Explanation:

472.  An Otto cycle has a clearance of 8%  and heat added of 1000 kJ. Find the heat rejected.

A. 564 kJ

B. 353 kJ

C. 709 kJ

D. 867 kJ

Explanation:

473. An  Otto cycle has a heat rejected of 300 kJ and work of 700 kJ. Find the cycle efficiency.

A. 56%

B. 60%

C. 70%

D. 50%

Explanation:

474.  An Otto cycle has a pressure ratio of 7. What is the cycle compression ratio?

A. 5.18

B. 6.34

C. 7.34

D. 4.01

Explanation:

475. Find the power of a rotating shaft which develops a torque of 188 N-m at 1350 rpm.

A. 101.54 hp

B. 53.63 hp

C. 63.35 hp

D. 35.63 hp

Explanation:

476.  Determine  the  pressure  exerted  on  a  diver  at  30 m  below  the  free  surface  of  the  sea. Assume a barometric pressure of 101 kPa and the specific gravity of sea water is 1.03.

A. 404 kPa

B. 410 kPa

C. 420 kPa

D. 430 kPa

Explanation:

477.  An air compressor has an inlet enthalpy of 35 Btu/lb and an exit enthalpy of 70 Btu/lb. The mass  flow  rate  of  air  is  3  lb/s.  If  the  heat  loss  is  466.62  Btu/min,  find  the  work  input to the compressor.

A. 139.59 hp

B. 149.59 hp

C. 159.59 hp

D. 169.59 hp

Explanation:

478.  An automobile tire is inflated to 35 psig at 54°F. After  being driven, the temperature rises to 80°F. Determine the final gage pressure assuming that the tire is inflexible.

A. 36.51 psig

B. 37.51 psig

C. 38.51 psig

D. 39.51 psig

Explanation:

479.  A  condenser  vacuum  gauge  reads  600  mm Hg  when  the  barometer  reads  760  mm Hg. What is the absolute condenser pressure in bar?

A. 0.0213

B. 0.061

C. 0.213

D. 0.610

Explanation:

480.  Water flows in a pipe at the rate of 10 kg/s. If the velocity of flow is 10 m/s, find the pipe diameter.

A. 30.23 mm

B. 35.68 mm

C. 38.39 mm

D. 42.39 mm

Explanation:

481.  What is the resulting pressure when one kilogram of air at 104 kPa and 98°C is heated at constant volume to 450°C?

A. 202.67 kPa

B. 194.67 kPa

C. 186.53 kPa

D. 198.65 kPa

Explanation:

482.  Determine the degrees of superheat of steam at 101.325 kPa and 170°C.

A. 50°C

B. 70°C

C. 60°C

D. 80°C

Explanation:

483.  Calculate the approximate enthalpy of water at 90°C.

A. 366.83 kJ/kg

B. 376.83 kJ/kg

C. 386.83 kJ/kg

D. 396.83 kJ/kg

Explanation:

484.  A Carnot cycle operates between 30°C and 350°C. Find the cycle efficiency.

A. 51.36%

B. 63.45%

C. 45.37%

D. 76.45%

Explanation:

485.  A Carnot cycle has a maximum temperature of 550°F and minimum temperature of 100°F. If the heat added is 4200 Btu/min, find the horsepower  output  of the engine.

A. 34.53

B. 40.56

C. 44.13

D. 65.40

Explanation:

486.  A  Carnot  cycle  has  a  sink  temperature  of  100°F  and  a  cycle  efficiency  of  70%.  Find  the temperature  of the heat source.

A. 1306.70°F

B. 1406.70°F

C. 1506.70°F

D. 1606.70°F

Explanation:

487.  The quality of steam is 20%. This means that:

A. mass of liquid is 20%, mass of vapor is 80%

B. mass of liquid is 20%, mass of vapor is 0%

C. mass of liquid is 80%, mass of vapor is 20%

D. none of these

Explanation:

488.  Fifty  kilograms  of  cooling  water  per  second  enter  the  condenser  at  25°C  and  leaves  at 50°C.  Find the heat carried away by water.

A. 1234.45 kW

B. 5233.75 kW

C. 2340.53 kW

D. 3140.25 kW

Explanation:

489.  Ten  kilograms  per  second  of  steam enter the turbine with an enthalpy of 3200 kJ/kg and enter the condenser with an enthalpy of 2500 kJ/kg in a Rankine cycle. If the turbine efficiency is 80% and the generator efficiency is 90%, determine the power  plant output.

A. 4320 kW

B. 3213 kW

C. 4056 kW

D. 5040 kW

Explanation:

490.  Determine the quality of steam in a vessel containing 2 kg of saturated vapor and 8 kg of saturated liquid.

A. 100%

B. 20%

C. 80%

D. 60%

Explanation:

491.  The condenser of a reheat power plant rejects heat at the rate of 600 kW. The mass flow rate  of  cooling  water  is  5  kg/s  and  the  inlet  cooling water temperature is 35°C. Calculate the condenser cooling water exit temperature.

A. 43.45°C

B. 53.45°C

C. 63.66°C

D. 74.34°C

Explanation:

492.  A heat engine has a thermal efficiency of 50%. How much power does the engine produce when heat is transferred at a rate of 109 kJ/hr?

A. 50 MW

B. 75 MW

C. 139 MW

D. 147 MW

Explanation:

493.  One  kilogram  of  air  is  compressed  adiabatically  and  in  a  steady-flow  manner.  The compression efficiency is 80% and the work done on the air is 265 kJ/kg. Compute the heat.

A. 212 kJ/kg

B. 100 kJ/kg

C. 0 kJ/kg

D. 331.25 kJ/kg

Explanation:

494.  Three-hundred  kilojoules  of  heat  flow  by  conduction  from  the  outside  to  the  inside  of  a cold  storage in one hour. If the temperature and all other conditions are the same, what is the heat flowing through the cold storage room in two hours?

A. 600 kJ

B. 900 kJ

C. 300 kJ

D. 1,200 kJ

Explanation:

495.  Determine the density of air at 760 mmHg absolute and 22°C?

A. 1.014 kg/m3

B. 1.316 kg/m3

C. 1.197 kg/m3

D. 1.266 kg/m3

Explanation:

496.  A refrigerating machine that is  classified as a one-ton machine has the capacity  to produce a cooling effect of?

A. 3.516 kW

B. 12,000 Btu/hr

C. 211 kJ/min

D. All of these