The friction in the nozzle __________ exit velocity of steam.
Has no effect on
Decreases
Increases
None of these
Correct Answer :
B. Decreases
Related Questions
The ratio of the temperature rise of cooling water to the vacuum temperature minus inlet cooling water temperature is called
Condenser efficiency
Vacuum efficiency
Nozzle efficiency
Boiler efficiency
The critical pressure ratio for gases is
0.528
0.546
0.577
0.582
The feed check valve is used in order to
Regulate flow of boiler water
Check level of water in boiler drum
Recirculate unwanted feed water
Allow high pressure feed water to flow to drum and not allow reverse flow to take place
The basic purpose of drum in boiler is to
Serve as storage of steam
Serve as storage of feed water for water wall
Remove salts from water
Separate steam from water
The reheat factor depends upon
Initial pressure and superheat
Exit pressure
Turbine stage efficiency
All of these
The density of supersaturated steam is about __________ that of the ordinary saturated vapour at the corresponding pressure.
Same as
2 times
4 times
8 times
The radius of a dished head is taken approximately as
One fourth
Half
One
Two
The diameter of Cornish boiler is of the order of
12 m
1.52.5 m
23 m
2.53.5 m
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
In regenerative air preheaters, the heat is transferred
From a metal wall from one medium to another
From heating an intermediate material and then heating the air from this material
By direct mixing
Heat is transferred by bleeding some gas from furnace
The aim of a compound steam engine is
To reduce the ratio of expansion in each cylinder
To reduce the length of stroke
To reduce the temperature range in each cylinder
All of the above
The indicated thermal efficiency is defined as the
Ratio of thermal efficiency to the Rankine efficiency
Ratio of brake power to the indicated power
Ratio of heat equivalent to indicated power to the energy supplied in steam
Product of thermal efficiency and Rankine efficiency
Which of the following statement is wrong?
Locomotive boiler is a water tube boiler
Water tube boilers are internally fired
Lamont boiler is a low pressure water tube boiler
All of the above
The ratio of the workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam is called
Blading efficiency
Nozzle efficiency
Stage efficiency
Mechanical efficiency
In a reaction turbine, when steam flows through the fixed blades,
Pressure increases while velocity decreases
Pressure decreases while velocity increases
Pressure and velocity both decreases
Pressure and velocity both increases
A throttle governed steam engine develops 15 kW with 280 kg per hour of steam and 35 kW with 520 kg per hour of steam. The steam consumption in kg per hour when developing 20 kW will be nearly
150 kg/h
210 kg/h
280 kg/h
340 kg/h
Water at pressure of 4 kg/cm² and 160°C temperature when exposed to atmosphere will
Boil
Flash i.e. get converted into steam
Remain as it was
Cool down
Locomotive boiler is a
Single tube, horizontal, internally fired and stationary boiler
Single tube, vertical, externally fired and stationary boiler
Multi-tubular, horizontal, internally fired and mobile boiler
Multi-tubular, horizontal, externally fired and stationary boiler
The length of Cornish boiler is of the order of
24 m
35 m
57.5 m
79 m
The effect of friction in the nozzle __________ dryness fraction of steam.
Has no effect on
Decreases
Increases
None of these
Fire tube boilers are
Internally fired
Externally fired
Internally as well as externally fired
None of these
In locomotives, the draught is produced by
Chimney
Induced draft fan
Both combined (A) and (B)
Steam jet draught
Which of the following boiler is best suited to meet the fluctuating demand of steam?
Locomotive boiler
Lancashire boiler
Cornish boiler
Babcock and Wilcox boiler
The specific heat of superheated steam in kcal/kg is generally of the order of
0.1
0.3
0.5
0.8
The high pressure boiler is one, which produces steam at a pressure more than
Atmospheric pressure
5 kg/cm²
10 kg/cm²
7580 kg/cm²
The device attached to the steam chest for preventing explosions due to excessive internal pressure of steam is called
Safety valve
Water level indicator
Pressure gauge
Fusible plug
The diameter of fire tubes in Cochran boiler is of the order of
2 cm
6 cm
8 cm
12 cm
Carbonisation of coal is the process of
Pulverising coal in inert atmosphere
Heating wood in a limited supply of air at temperatures below 300°C
Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
Binding the pulverised coal into briquettes
When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be
Choked
Under-damping
Over-damping
None of these
The pressure at which latent heat of vaporisation of water is zero, is
Below atmospheric pressure
1 kg/cm²
100 kg/cm²
225.6 kg/cm²