Mechanical Engineering Mcqs

A. inherent moisture and surface mois¬ture are different things
B. in some coals moisture may be present upto 40%
C. some moisture in coal helps in better burning which is not possible with completely dry coal
D. it increases thermal efficiency
E. moisture in coal is removed before firing by heating it with hot air

A. to provide proper conditions for con-tinuous complete combustion
B. mix fuel with air and ignite
C. separate ash from coal
D. maintain heat supply to prepare and ignite the incoming fuel
E. to minimise radiation losses

A. high burning rate is possible
B. heat release can be easily controlled
C. fuel burns economically
D. it is the best technique for burning high ash content fuel having low fusion ash
E. separate mills are required to powder the coal

A. high calorific value
B. produce minimum smoke and gases
C. ease in storing
D. high ignition point
E. ecomomical

A. 15%
B. 20%
C. 30%
D. 45%
E. 60%.

A. one-fourth
B. half
C. one
D. two
E. three

A. boiler efficiency, turhine efficiecny, generator efficiency
B. all the three above plus gas cycle efficiency
C. carnot cycle efficiency
D. regenerative cycle efficiency
E. rankine cycle efficiency

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. 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
C. feed pump is employed to supplement natural circulation in water wall type furnace
D. water is converted into steam in one pass without any recirculation
E. water is heated in a large number of tubes

A. heat carried away by flue gases
B. heat carried away by ash
C. moisture present in fuel and steam formed by combustion of hydrogen in fuel
D. radiation
E. all of the above

A. lancashire boiler
B. locomotive boiler
C. babcock and wilcox boiler
D. cochran boiler
E. benson boiler