Mechanical Engineering - Steam Boilers and Engines

36. 

The boiler efficiency is given by (where m = Total mass of water evaporated into steam in kg/h, mf = Mass of fuel in kg/h, C = Calorific valve of fuel in kJ/kg of fuel, h = Total heat of steam in kJ/kg, and hf1 = Sensible heat of feed water in kJ /kg)

A.
B.
C.
D.

Answer: Option C

Explanation:

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37. 

In a boiler, the heat is lost

A. to dry flue gases
B. in moisture present in the fuel
C. to steam formed by combustion of hydrogen per kg of fuel
D. all of the above

Answer: Option D

Explanation:

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38. 

The crown of the fire box is made hemispherical in order to resist intense heat in the fire box.

A. True
B. False

Answer: Option A

Explanation:

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39. 

For maximum discharge through a chimney, the condition is that height of hot gas column producing the draught should be

A. one-half the height of chimney
B. equal to the height of chimney
C. two times the height of chimney
D. four times the height of chimney

Answer: Option B

Explanation:

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40. 

Water tube boilers are

A. internally fired
B. externally fired
C. internally as well as externally fired
D. none of these

Answer: Option B

Explanation:

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