The difference of supersaturated temperature and saturation temperature at that pressure is called
Degree of super-saturation
Degree of superheat
Degree of under-cooling
None of these
Correct Answer :
C. Degree of under-cooling
Related Questions
In an impulse turbine
The steam is expanded in nozzles only and there is a pressure drop and heat drop
The steam is expanded both in fixed and moving blades continuously
The steam is expanded in moving blades only
The pressure and temperature of steam remains constant
Primary air is the air used to
Provide air around burners for obtaining optimum combustion
Transport and dry the coal
Convert CO (formed in lower zone of furnace) into CO₂ at higher zone
Air delivered by forced draft fan
Benson boiler requires
No drum
One drum
Two drums
Three drums
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
The latent heat of steam with increase of pressure
Remain same
Increases
Decreases
Behaves unpredictably
The specific volume of steam with increase in pressure decreases
Linearly
Slowly first and then rapidly
Rapidly first and then slowly
Inversely
Secondary air is the air used to
Provide air around burners for obtaining optimum combustion
Transport and dry the coal
Convert CO (formed in lower zone of furnace) into CO₂ at higher zone
Air delivered by induced draft fan
Spontaneous combustion is a phenomenon in which
All the fuel burns instantaneously producing high energy release
Fuel burns with less air
Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
Explosion in furnace
Thermal efficiency of a thermal power plant is of the order of
15 %
20 %
30 %
45 %
The stage efficiency (ηS) is given by (where ηB = Blading efficiency, and ηN = Nozzle efficiency)
ηS = ηB × ηN
ηS = ηB / ηN
ηS = ηN / ηB
None of these
The evaporation of 15.653 kg of water per hour from and at 100°C is called
Evaporative capacity
Factor of evaporation
Equivalent evaporation
One boiler h.p.
The overall efficiency of thermal power plant is
Boiler efficiency, turbine efficiency, generator efficiency
All the three above plus gas cycle efficiency
Carnot cycle efficiency
Regenerative cycle efficiency
The rate of steam produced in Benson boiler is
100 tonnes/h
135 tonnes/h
175 tonnes/h
250 tonnes/h
All steam engines work on
Zeroth law of thermodynamics
First law of thermodynamics
Second law of thermodynamics
None of these
Willians line for the steam engine is a straight line relationship between the steam consumption per hour and
Indicated power
Brake power
Efficiency
Pressure of steam
Boiler H.P. is defined as the
Steam evaporation rate per kg of fuel fired
Work done in evaporating 1 kg of steam per hour from and at 100°C into dry saturated steam
The evaporation of 15.65 kg of water per hour from and at 100°C into dry saturated steam
Work done by 1 kg of steam at saturation condition
Relative percentage of heat absorbed through the heat transfer of (i) Furnace water wall (ii) Boiler tank (iii) Superheater (iv) Economiser (v) Air-heater of a typical boiler of 200 MW capacity would be of the order of
48 : 20 : 15 : 7 : 10
10 : 7 : 15 : 20 : 48
20 : 48 : 7 : 15 : 10
7 : 15 : 20 : 10 : 48
Willians line follows the law (where b = A constant representing the shape of the Willians line, a = Another constant i.e. no load consumption per hour, I.P. = Indicated power, and m = Steam consumption per hour)
I.P. = a × m + b
m = a + b × I.P.
I.P. = b × m + a
m = (b/I.P.) - a
The draught in locomotive boilers is produced by a
Chimney
Centrifugal fan
Steam jet
None of these
Which of the following boilers is best suited to meet fluctuating demands?
Babcock and Wilcox
Locomotive
Lancashire
Cochran
In a 50% reaction turbine stage, tangential component of absolute velocity at rotor inlet is 537 m/s and the blade velocity is 454 m/s. The power output in kW of steam will be
260 kW
282 kW
296 kW
302 kW
Which of the following statement is wrong?
The mechanical draught reduces the height of chimney.
The natural draught reduces the fuel consumption.
A balanced draught is a combination of induced and forced draught.
All of the above
Cut-off governing of steam engines is a method of controlling the engine output by varying
Volume of intake steam
Pressure of intake steam
Temperature of intake steam
All of these
A valve installed between the boiler and the feed pump is
Blow off cock
Feed check valve
Steam stop valve
None of these
The ratio of heat equivalent to brake power to the energy supplied in steam is known as
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Brake thermal efficiency
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 efficiency of steam turbines may be improved by
Reheating of steam
Regenerative feed heating
Binary vapour plant
Any one of these
The fire tubes in, a Coarran and Scottish marine boiler are
Horizontal
Vertical
Inclined
Both horizontal and vertical
The steam enters the nozzle at a
High pressure and a low velocity
High pressure and a high velocity
Low pressure and a low velocity
Low pressure and a high velocity
Throttle governing of steam engines is a method of controlling the engine output by varying
Volume of intake steam
Pressure of intake steam
Temperature of intake steam
All of these