⚙️Mechanical Engineering MCQs
Mechanical Engineering MCQs
488 MCQs411
In a recuperative air preheater, the heat is transferred____________________?
Afrom a metal wall from one medium to another
Bfrom heating an itermediate material and then heating the air from this material
Cby direct mixing ,
Dheat is transferred by bleeding some gases from furnace E. none of the above
412
The temperature of flue gases at air heater outlet should be__________________?
A100°C
Babove dew-point temperature of flue gases
Cbelow dew-point temperature of flue gases
Dless than wet bulb temperature of flue gases E. above wet bulb temperature of flue gases
413
In designing air preheater, the important design consideration is that_________________?
Aapproach temperature should be as low as possible
Bhandling and maintenance should be easier
Cheat transfer area should be optimum
Dstack gases should not be cooled to the dew point E. none of the above
414
The function of injector used in small capacity boilers is to____________________?
Acreate vacuum
Binject chemical solution in feed pump
Cpump water, similar to boiler feed pump
Dadd make up water in the system E. none of the above
415
The height of chimney in a power plant is governed by__________________?
Athe draft to be created
Blimitation of construction facilities
Ccontrol of pollution
Dquantity of flue gases to be handled E. all of the above
416
Vacuum for reciprocating steam engines compared to steam turbines is__________________?
Amore
Bequal
Cless
Dcould be more or less depending on the size of plant E. none of the above
417
In locomotives, the draught is produced by_________________?
Aand
BD. steam jet draught E. none of the above
Cboth combined
418
The maximum discharge through a chimney occurs when the height of chimney is_____________________?
Ainfinitely long
Baround 200 meters
Cequal to the height of the hot gas column producing draught
Doutside temperature is very low E. more than the tallest building nearby
419
Tertiary air is the air used to____________________?
Aprovide air around burners for obtaining optimum combustion
Btransport and dry the coal
Ccool the scanners
Dsupply air for ignitors E. convert CO (formed in lower zone of furnace) into C02 at higher zone
420
Which is not the correct statement about moisture in coal ______________________?
Ainherent moisture and surface mois¬ture are different things
Bin some coals moisture may be present upto 40%
Csome moisture in coal helps in better burning which is not possible with completely dry coal
Dit increases thermal efficiency E. moisture in coal is removed before firing by heating it with hot air