mechanical engineering MCQs – Page 174

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

mechanical engineering Mcqs

1. compressors gas turbines and jet engines 2. theory of machines 3. nuclear power plants 4. engineering materials 5. strength of materials mechanical engineering 6. thermodynamics 7. heat transfer 8. i c engines 9. steam boilers engines nozzles and turbines 10. engineering mechanics 11. fluid mechanics mechanical engineering 12. production technology 13. machine design 14. hydraulic machines 15. workshop technology 16. refrigeration and air conditioning

3461. Ultimate analysis of fuel is determination of percentage of____________________?
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A. lower calorific value

B. higher calorific value

C. best analysis

D. carbon, hydrogen, nitrogen, sulphur, moisture

E. fixed carbon, ash, volatile matter, moisture

3462. The heat loss in a boiler takes place in the form of________________?
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A. heat carried away by flue gases

B. moisture present in fuel and steam formed by combustion of hydrogen in fuel

C. all of the above

D. heat carried away by ash

E. radiation

3463. Pulverized fuel is used for___________________?
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A. stoker fired boilers

B. better burning

C. medium sized units

D. more calorific value

E. less radiation loss

3464. Deaeration of feed water is carried out because it reduces ____________________?
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A. weight of water to be handled

B. corrosion caused by oxygen

C. pH value of water

D. cavitation of .boiler feed pumps

E. heat transfer coefficient

3465. The three Ts for good combustion are____________________?
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A. thorough mixing, total air, and temperature

B. total air, time, and temperature

C. temperature, time, and turbulance

D. none of the above

E. total air, true fuel, and turbulance

3466. In designing air preheater, the important design consideration is that_________________?
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A. stack gases should not be cooled to the dew point

B. handling and maintenance should be easier

C. heat transfer area should be optimum

D. approach temperature should be as low as possible

E. none of the above

3467. Which is not correct statement about effect of sulphur in fuel ___________________?
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A. it erodes furnace walls

B. it helps in electrostatic precipitation of ash in flue-gases

C. it has heating value

D. it leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low

E. none of the above

3468. The number of drums in Benson steam generator is_________________?
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A. two

B. none of the above

C. no drum

D. one

E. one steam drum and one water drum

3469. An economiser in a boiler______________________?
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A. increases life of boiler

B. decreases fuel consumption

C. increases steam pressure

D. decreases steam pressure

E. increases steam flow

3470. Which is not correct statement about pulverised fuel firing ?
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A. separate mills are required to powder the coal

B. heat release can be easily controlled

C. it is the best technique for burning high ash content fuel having low fusion ash

D. fuel burns economically

E. high burning rate is possible

3471. Evaporative capacity of boiler is expressed as____________________?
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A. steam pressure produced

B. kg of steam produced

C. kg of fuel fired

D. kg of steam produced per kg of fuel fifed

E. kg of water evaporated

3472. The major axis of elliptical manholes on the shell should be provided___________________?
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A. vertically

B. circumferentially

C. on dished end

D. anywhere

E. longitudinally

3473. Film boling occurs at _______________________?
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A. very low pressure

B. very high pressures

C. medium pressures

D. none of the above

E. atmospheric pressures

3474. Secondary air is the used to_________________?
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A. convert CO (formed in lower zone of furnace) into C02 at higher zone

B. air delivered by induced draft fan

C. air fed to pulverisers

D. transport and dry the coal

E. provide air around burners for obtaining optimum combustion

3475. Thermal efficiency of well maintained boiler will be of the order___________________?
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A. 40%

B. 50%

C. 20%

D. 75%

E. 90%

3476. Thermal efficiency of a thermal power plant is of the order of___________________?
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A. 60%.

B. 20%

C. 30%

D. 15%

E. 45%

3477. For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has ____________________?
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A. heating surface depends on other parameters

B. equal heating surface

C. less heating surface

D. more heating surface

E. none of the above

3478. Reheating of steam under ideal conditions takes place at constant __________________?
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A. enthaply

B. temperature

C. all of the above

D. entropy

E. pressure

3479. In forced circulation type boiler__________________?
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A. heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum

B. feed pump is employed to supplement natural circulation in water wall type furnace

C. water is converted into steam in one pass without any recirculation

D. water is heated in a large number of tubes

E. water is supplied in drum and through down-comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam

3480. During storage, the heating value of coal __________________?
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A. increases

B. may increase or decrease depending upon the method of storage

C. none of the above

D. decreases

E. remains constant

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