While steam expands in turbines, theoretically the entropy
Remains constant
Increases
Decreases
Behaves unpredictably
Correct Answer :
A. Remains constant
Related Questions
The compounding of turbines is done in order to
Reduce speed of rotor
Improve efficiency
Reduce exit losses
All of these
In a boiler, the heat is lost
To dry flue gases
In moisture present in the fuel
To steam formed by combustion of hydrogen per kg of fuel
All of the above
A stage, in reaction turbine, is represented by
Number of casing
Number of entries of steam
Number of exits of steam
Each row of blades
A regenerative steam cycle renders
Increased work output per unit mass of steam
Decreased work output per unit mass of steam
Increased thermal efficiency
Decreased work output per unit mass of steam as well as increased thermal efficiency
Hard coke is used in
Cement industry
Thermal power plant
Blast furnace
Domestic use
The diagram 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
Pick up wrong statement about desired properties of a good fuel
High calorific value
Produce minimum smoke and gases
Ease in storing
High ignition point
On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by
Horizontal straight line
Vertical straight line
Straight inclined line
Curved line
In a steam engine, superheated steam from the boiler is fed into the steam chest at a pressure of
10 atmospheres
20 atmospheres
30 atmospheres
40 atmospheres
Which of the following statement is correct?
A horizontal steam engine requires less floor area than a vertical steam engine
The steam pressure in the cylinder is not allowed to fall below the atmospheric pressure
The compound steam engines are generally non-condensing steam engines
All of the above
The equivalent evaporation of a boiler is a measure to compare
The given boiler with the model
The two different boilers of the same make
Two different makes of boilers operating under the same operating conditions
Any type of boilers operating under any conditions
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
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
During storage, the heating value of coal
Increases
Decreases
Remain constant
May increase or decrease depending upon the method of storage
The effect of super-saturation is that the
Mass of the steam discharged increases
Entropy and specific volume of the steam increases
Exit velocity of steam reduces
All of these
The ratio of the energy required to produce the artificial draught (expressed in metres head or J/kg of flue gas) to the mechanical equivalent of extra heat carried away per kg of flue gases due to natural draught, is known as
Efficiency of the boiler
Efficiency of the chimney
Efficiency of the fan
Power of the boiler
Latent heat of dry steam at atmospheric pressure is equal to
539 kcal/ kg
539 BTU/ lb
427 kcal/ kg
100 kcal/ kg
The maximum efficiency of a De-Laval turbine is (where α = Nozzle angle)
sin²α
cos²α
tan²α
cot²α
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
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
Which of the following is a fire tube boiler?
Lancashire boiler
Babcock and Wilcox boiler
Yarrow boiler
None of these
Which of the following boilers is best suited to meet fluctuating demands?
Babcock and Wilcox
Locomotive
Lancashire
Cochran
Which of the following boiler works on a forced circulation of water?
Lamont boiler
Benson boiler
Loeffler boiler
All of these
Which of the following statement is wrong?
The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.
The flow in the convergent portion of the nozzle is subsonic.
The flow in the divergent portion of the nozzle is supersonic.
To increase the velocity of steam above sonic velocity (supersonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary.
The process of maintaining the speed of the turbine constant for various load conditions, is known as
Bleeding
Reheating
Governing
None of these
Reheating of steam under ideal conditions takes place at constant
Entropy
Enthalpy
Pressure
Temperature
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
The impulse reaction turbine has its driving force
As an impulsive force
As a reaction force
Partly as an impulsive force and partly as a reaction force
None 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