Practice Test: Question Set - 13
1. The effect of friction in the nozzle __________ dryness fraction of steam.
- (A) Has
no effect on
- (B) Decreases
- (C) Increases
- (D) None
of these
2. The overall efficiency of thermal power plant is
- (A) Boiler efficiency,
turbine efficiency, generator efficiency
- (B) All the three above
plus gas cycle efficiency
- (C) Carnot cycle
efficiency
- (D) Regenerative cycle
efficiency
3. A compound steam engine in which piston rods of high pressure and low pressure cylinders are attached to two different cranks set at 90° to each other, is called
- (A) Receiver
type compound engine
- (B) Tandem
type compound engine
- (C) Woolf
type compound engine
- (D) Both
(A) and (B)
4. In locomotives, the draught is produced by
- (A) Chimney
- (B) Induced draft fan
- (C) Both combined (A) and
(B)
- (D) Steam jet draught
5. The efficiency of an impulse turbine is maximum when (where Vb = Blade speed, V = Absolute velocity of steam entering the blade, and α = Nozzle angle)
- (A) Vb
= 0.5 V cosα
- (B) Vb
= V cosα
- (C) Vb
= 0.5 V² cosα
- (D) Vb
= V² cosα
6. The draught (in mm of water), for maximum discharge of flue gases through the chimney, is given by (where H = Height of the chimney in meters, and T1 = Absolute temperature of air outside the chimney in K)
- (A) T1
/88.25H
- (B) 88.25H/T1
- (C) T1
/176.5H
- (D) 176.5H/T1
7. The behavior of coal in a furnace is determined by
- (A) The content of sulphur
- (B) The content of ash
and heating value
- (C) The proximate
analysis
- (D) The exact analysis
8. The efficiency of a pressure-velocity compounded impulse turbine is __________ as compared to pressure compounded impulse turbine.
- (A) Same
- (B) Less
- (C) More
- (D) None
of these
9. An economiser is generally placed between
- (A) Last
superheater or reheater and air preheater
- (B) Induced
draft fan and forced draft fan
- (C) Air
preheater and chimney
- (D) None
of the above
10. In order to obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will
- (A) Remain unaffected
- (B) Improve
- (C) Worsen
- (D) May improve/worsen
depending on size
11. The maximum discharge of steam through a convergent-divergent nozzle depends upon
- (A) Area
of nozzle at throat
- (B) Initial
pressure and volume of steam
- (C) Final
pressure of steam leaving the nozzle
- (D) Both
(A) and (B)
12. 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
13. The critical pressure at which latent heat of vaporisation is zero is
- (A) 225.65 kgf/ cm²
- (B) 273 kgf/ cm²
- (C) 100 kgf/ cm²
- (D) 1 kgf/ cm²
14. The effect of bleeding is that
- (A) It
increases the thermodynamic efficiency of the turbine
- (B) Boiler
is supplied with hot water
- (C) It
decreases the power developed by the turbine
- (D) All
of the above
15. Which of the following statement is correct for a compound steam engine?
- (A) The
cost of the engine, for the same power and economy, is more than that of a
simple steam engine
- (B) The
forces in the working parts are increased as the forces are distributed over
more parts
- (C) The
ratio of expansion is reduced, thus reducing the length of stroke
- (D) The
temperature range per cylinder is increased, with corresponding increase in
condensation