Steam Boilers Engines Nozzles and Turbines

31. During storage, the heating value of coal

  1. increases
  2. decreases
  3. remains constant
  4. may increase or decrease depending upon the method of storage
  5. none of the above.

Correct answer: (B)
decreases

32. Efficiency of a thermal cycle increases by

  1. regeneration
  2. reheating of steam
  3. both (a) and (b)
  4. cooling of steam
  5. none of the above.

Correct answer: (C)
both (a) and (b)

33. Efficiency of rankine cycle can be increased by

  1. decreasing initial steam pressure and temperature
  2. increasing exhaust pressure
  3. decreasing exhaust pressure
  4. increasing the expansion ratio
  5. increasing number of regenerative heaters.

Correct answer: (A)
decreasing initial steam pressure and temperature

34. Equivalent evaporation is the amount of water evaporated in a boiler from and at

  1. 0°C
  2. 100°C
  3. saturation temperature at given pressure
  4. room temperature
  5. 20°C.

Correct answer: (B)
100°C

35. Equivalent evaporation of water is the evaporation "for a feed water supply at 100°C

  1. and its corresponding conversion into dry saturated steam at 100°C and 1.033 kg/cm2
  2. and its corresponding conversion into dry steam at desired boiler pressure
  3. conversion into steam at atmospheric condition
  4. conversion into steam at the same pres-sure at which feed water is supplied
  5. none of the above.

Correct answer: (A)
and its corresponding conversion into dry saturated steam at 100°C and 1.033 kg/cm2

36. Evaporative capacity of boiler is expressed as

  1. kg of steam produced
  2. steam pressure produced
  3. kg of fuel fired
  4. kg of steam produced per kg of fuel fifed
  5. kg of water evaporated.

Correct answer: (D)
kg of steam produced per kg of fuel fifed

37. Expanding steam to a very low prseeure (high vacuum) in steam engines is

  1. desirable
  2. economical
  3. essential
  4. optional
  5. uneconomical.

Correct answer: (E)
uneconomical.

38. Feed water conditioning in thermal power plants in done to

  1. reduce hardness and for removal of solids
  2. increase efficiency-of thermal power plant
  3. increase *heat transfer rate
  4. increase steam parameters
  5. all of the above.

Correct answer: (A)
reduce hardness and for removal of solids

39. Film boling occurs at

  1. very low pressure
  2. atmospheric pressures
  3. medium pressures
  4. very high pressures
  5. none of the above.

Correct answer: (D)
very high pressures

40. Fire tube boilers are limited to a maximum design working pressure of

  1. 1 kg/cm
  2. 6 kg/cm
  3. 17 kg/cm2
  4. 100 kg/cm2
  5. 250 kg/cm2.

Correct answer: (C)
17 kg/cm2

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