Expanding steam to a very low pressure (high vacuum) in steam engines is
Desirable
Economical
Essential
Uneconomical
Correct Answer :
D. Uneconomical
Related Questions
The water tubes in a Babcock and Wilcox boiler are
Horizontal
Vertical
Inclined
Horizontal and inclined
On Millier chart, the constant pressure lines
Diverge from left to right
Diverge from right to left
Are equally spaced throughout
First rise up and then fall
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
Hygrometry deals with the
Hygroscopic substances
Water vapour in air
Temperature of air
Pressure of air
During polytropic process
Heat transfer takes place across cylinder walls
Work is done
Steam may be wet, dry or superheated after expansion
All of the above
In a Woolf type compound engine, the high pressure and low pressure cylinders
Have common piston rod
Are set at 90°
Have separate piston rod
Are set in V-arrangement
Equivalent evaporation is the amount of water evaporated in a boiler from and at
0°C
100°C
Saturation temperature at given pressure
Room temperature
The clearance in the engine cylinder
Increases the mean effective pressure
Increases the workdone
Decreases the efficiency of the engine
All of these
The basic job of feed water treatment in boilers is to overcome the problem of
Corrosion
Scale
Carryover
All of the above
The variation of steam pressure in the nozzle depends upon
Velocity of steam
Specific volume of steam
Dryness fraction of steam
All of these
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
Fire tube boilers are limited to a maximum working pressure of
0.17 MN/m²
1.7 MN/m²
17 MN/m²
170 MN/m²
Reheating of steam under ideal conditions takes place at constant
Entropy
Enthalpy
Pressure
Temperature
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
Water tube boilers are
Internally fired
Externally fired
Internally as well as externally fired
None of these
In a uniflow engine
Steam enters and exhausts through the same port
Steam enters at one end and exhausts at the centre
Steam enters at the centre and exhausts at the other end
None of the above
Thermal equilibrium means that the flow of steam is
Isothermal
Isentropic
Hyperbolic
Polytropic
Which of the following statement indicates the difference between Cornish boiler and Lancashire boiler?
Cornish boiler is a water tube boiler whereas Lancashire boiler is a fire tube boiler
Cornish boiler is a fire tube boiler whereas Lancashire boiler is a water tube boiler
Cornish boiler has one flue tube whereas Lancashire boiler has two flue tubes
Cornish boiler has two flue tubes whereas Lancashire boiler has one flue tube
The diameter of fire tubes in Cochran boiler is of the order of
2 cm
6 cm
8 cm
12 cm
By compounding the expansion of steam in two or more cylinders, the length of stroke
Does not change
Increases
Decreases
None of these
A safety valve in a locomotive starts leaking. The leaking medium will be
Water
Dry steam
Wet steam
Super heated steam
In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts. and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is
40 %
25 %
50 %
80 %
Which of the following is correct? (Where pa = Actual mean effective pressure, pm = Theoretical mean effective pressure, and K = Diagram factor)
pa = pm/K
pa = pm × K
pa = K/pm
pa = pm + K
A binary vapour plant consists of
Steam turbine
Steam condenser
Mercury boiler
All of these
The pressure of steam __________ while flowing through a nozzle.
Increases
Decreases
Remains constant
None of these
Thermal efficiency of a thermal power plant is of the order of
15 %
20 %
30 %
45 %
Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler
Increases
Decreases
Remain unaffected
First increases and then decreases
The specific heat of superheated steam in kcal/kg is generally of the order of
0.1
0.3
0.5
0.8
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 length of shell of a Locomotive boiler is
1 m
2 m
3 m
4 m