The effect of friction in the nozzle __________ dryness fraction of steam.
Has no effect on
Decreases
Increases
None of these
Correct Answer :
C. Increases
Related Questions
A device used in a boiler to control the flow of steam from the boiler to the main pipe and to shut off the steam completely when required, is known as
Blow off cock
Fusible plug
Superheater
Stop valve
The effect of bleeding is that
It increases the thermodynamic efficiency of the turbine
Boiler is supplied with hot water
It decreases the power developed by the turbine
All of the above
The diameter of internal flue tubes of a Lancashire boiler is about _________ that of its shell.
One-fourth
One-third
Two-fifth
One-half
The length of Cornish boiler varies from
2 to 4.5 m
3 to 5 m
5 to 7.5 m
7 to 9 m
De-Laval turbines are mostly used
Where low speeds are required
For small power purposes and low speeds
For large power purposes
For small power purposes and high speeds
The velocity of whirl at outlet for an axial discharge turbine is
Minimum
Maximum
Zero
None of these
Fire tube boilers are
Internally fired
Externally fired
Internally as well as externally fired
None of these
The theoretical indicator diagram of a simple steam engine is based upon the assumption that
There is no pressure drop due to condensation
Steam is admitted at boiler pressure and exhausted at condenser pressure
The expansion (or compression) of the steam is hyperbolic
All of the above
A safety valve mainly used with locomotive and marine boilers is
Lever safety valve
Dead weight safety valve
High steam and low water safety valve
Spring loaded safety valve
A vessel into which the steam is exhausted and condensed after doing work in an engine cylinder or turbine is known as
Steam condenser
Steam boiler
Steam preheater
Economiser
In locomotives, the draught is produced by
Chimney
Induced draft fan
Both combined (A) and (B)
Steam jet draught
In water tube boilers
Water passes through the tubes which are surrounded by flames and hot gases
The flames and hot gases pass through the tubes which are surrounded by water
Forced circulation takes place
None of these
The ratio of the clearance volume to the swept volume is called
Cut-off ratio
Expansion ratio
Clearance ratio
None of these
Which of the following varieties of coals is mostly used in steam boilers?
Non-coking bituminous coal
Brown coal
Peat
None of the above
The relative heat absorption for successively added equal areas of boiler convection heating surfaces
Increases
Decreases
Remain unaffected
First increases and then decreases
In a reaction turbine
The steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades
The expansion of steam takes place partly in the fixed blades and partly in the moving blades
The steam is expanded from a high pressure to a condenser pressure in one or more nozzles
The pressure and temperature of steam remains constant
The amount of water evaporated from feed water at _________ into dry and saturated steam at 100° C at normal atmospheric pressure is called equivalent evaporation from and at 100° C.
0°C
40°C
60°C
100°C
The efficiency of reaction turbine is maximum when (where α = Angle made by the absolute velocity V at inlet)
Vb = 0.5 V cosα
Vb = V cos α
Vb = 0.5 V² cosα
Vb = V² cosα
The efficiency of a boiler is defined as
Ratio of heat actually used in producing steam to the heat liberated in the furnace
Ratio of the mass of steam produced to the mass of total water supplied in a given time
Ratio of the heat liberated in the furnace to the heat actually used in producing steam
None of the above
Alkaline pyrogallate is used in Orsat's apparatus for absorption of
CO₂
CO
O₂
N₂
On Mollier chart, flow through turbine is represented by
Horizontal straight line
Vertical straight line
Straight inclined line
Curved line
Heating of dry steam above saturation temperature is known as
Enthalpy
Superheating
Super saturation
Latent heat
With increase in load, radiant superheater has
Drooping characteristic
Linear characteristic
Rising characteristic
Flat characteristic
In case of condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is _________ the atmospheric pressure.
Equal to
Lower than
Higher than
None of these
A device used to heat feed water by utilising the heat in me exhaust flue gases before leaving through the chimney, is known as
Economiser
Fusible plug
Superheater
Stop valve
The shell diameter and length of locomotive boiler are
1.5 m, 4 m
1.5 m, 6 m
1 m, 4 m
2 m, 4 m
Stage efficiency is also known as
Diagram efficiency
Nozzle efficiency
Gross efficiency
None of these
If the critical pressure ratio for steam is 0.546, then the steam is initially
Wet steam
Dry saturated steam
Superheated steam
None of these
The nozzle efficiency is the ratio of
Workdone on the blades to the energy supplied to the blades
Workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
Energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
None of the above
In a single acting steam engine
The steam is admitted on one side of the piston and one working stroke is produced during each revolution of the crankshaft
The steam is admitted, in turn, on both sides of the piston and one working stroke is produced during each revolution of the crankshaft
The steam is admitted on one side of the piston and two working strokes are produced during each revolution of the crankshaft
The steam is admitted, in turn, on both sides of the piston and two working strokes are produced during each revolution of the crankshaft