A diesel engine is _________ as compared to petrol engine, both running at rated load.
Equally efficient
Less efficient
More efficient
None of these
Correct Answer :
C. More efficient
Related Questions
By higher octane number of spark ignition fuel, it is meant that the fuel has
Higher heating value
Higher flash point
Lower volatility
Longer ignition delay
The theoretically correct mixture of air and petrol is
10 : 1
15 : 1
20 : 1
25 : 1
The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will
Increase
Decrease
Be independent
May increase or decrease depending on other factors
The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of
Morse test
Prony brake test
Motoring test
Heat balance test
A petrol engine, during suction stroke draws
Air only
Petrol only
A mixture of petrol and air
None of these
The compensating jet in a carburettor supplies almost constant amount of petrol at all speeds because the
Jet area is automatically varied depending on the suction
The flow from the main jet is diverted to the compensating jet with increase in speed
The diameter of the jet is constant and the discharge coefficient is invariant
Flow is produced due to the static head in the float chamber
In a diesel engine, the duration between the time of injection and ignition, is known as
Pre-ignition period
Delay period
Period of ignition
Burning period
In compression ignition engines, swirl denotes a
Haphazard motion of the gases in the chamber
Rotary motion of the gases in the chamber
Radial motion of the gases in the chamber
None of the above
In a petrol engine, the mixture has the lowest pressure at the
Beginning of suction stroke
End of suction stroke
End of compression stroke
None of these
The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called
Mechanical efficiency
Overall efficiency
Volumetric efficiency
Relative efficiency
The reflectivity depends upon
Geometry of the reflector
Energy of neutrons
Properties of the reflector
All of these
Which of the following does not relate to a compression ignition engine?
Fuel pump
Fuel injector
Governor
Carburettor
As compared to air standard cycle, in actual working, the effect of variation in specific heats is to
Increase maximum pressure and maximum temperature
Reduce maximum pressure and maximum temperature
Increase maximum pressure and decrease maximum temperature
Decrease maximum pressure and increase maximum temperature
The operation of forcing additional air under pressure into the engine cylinder is known as
Supercharging
Carburetion
Turbulence
Delay period
The fuels in order of decreasing knock tendency for spark ignition engines are
Paraffin, aromatic, napthene
Paraffin, napthene, aromatic
Napthene, aromatics, paraffin
Napthene, paraffin, aromatic
In a four stroke cycle petrol engine, the charge is ignited at
30° before top dead centre
30° after top dead centre
30° before bottom dead centre
30° after bottom dead centre
As a result of detonation in an I.C. engine, following parameter attains very high value
Peak pressure
Rate of rise of pressure
Rate of rise of temperature
Peak temperature
The ratio of the indicated thermal efficiency to the air standard efficiency is known as
Mechanical efficiency
Overall efficiency
Volumetric efficiency
Relative efficiency
Most high speed compression engines operate on
Diesel cycle
Otto cycle
Dual combustion cycle
Special type of air cycle
The correct sequence of the decreasing order of brake thermal efficiency of the three given basic types of engines is
Four stroke C.I. engine, four stroke S.I. engine, two stroke S.I. engine
Four stroke S.I. engine, four stroke C.I. engine, two stroke S.I. engine
Four stroke C.I. engine, two stroke S.I. engine, four stroke S.I. engine
Two stroke S.I. engine, four stroke S.I. engine, four stroke C.I. engine
The following volume of air is required for consuming 1 litre of fuel by a four stroke engine
1 m3
5 m3
56 m3
910 m3
The injection pressure in a diesel engine is about
10 bar
100 bar
150 bar
500 bar
The brake power of a diesel engine, keeping other parameters constant, can be increased by
Decreasing the density of intake air
Increasing the temperature of intake air
Increasing the pressure of intake air
Decreasing the pressure of intake air
The ignition of the charge by some hot surface within the engine before the passage of spark is called
Pre-ignition
Detonation
Ignition delay
Auto-ignition
A carburettor is used to supply
Petrol, air and lubricating oil
Air and diesel
Petrol and lubricating oil
Petrol and air
Pick up the wrong statement about supercharging
Supercharging reduces knocking in diesel engines
There can be limited supercharging in petrol engines because of detonation
Supercharging at high altitudes is essential
Supercharging results in fuel economy
In the opposed piston diesel engine, the combustion chamber is located
Above the piston
Below the piston
Between the pistons
There is no such criterion
The pressure inside the cylinder is _________ the atmospheric pressure during the exhaust stroke.
Equal to
Below
Above
None of these
In a typical medium speed 4-stroke cycle diesel engines
Exhaust valve opens at 35° before bottom dead centre and closes at 20° after top dead centre
Exhaust valve opens at bottom dead centre and closes at top dead centre
Exhaust valve opens just after bottom dead centre and closes just before top dead centre
May open and close anywhere
The brake power is the power available
In the engine cylinder
At the crank shaft
At the crank pin
None of these