# 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
(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 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

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