In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of
250°C
500°C
1000°C
2000°C
Correct Answer :
C. 1000°C
Related Questions
Stoichiometric ratio is
Chemically correct air-fuel ratio by weight
Chemically correct air-fuel ratio by volume
Actual air-fuel ratio for maximum efficiency
None of the above
The working pressure and temperature inside the cylinder of an internal combustion engine is _________ as compared to a steam engine.
Low
Very low
High
Very high
A supercharged engine as compared to an ordinary engine
Requires smaller foundation
Is lighter
Consumes less lubricating oil
All of these
Scavenging air in diesel engine means
Air used for combustion sent under pressure
Forced air for cooling cylinder
Burnt air containing products of combustion
Air used for forcing burnt gases out of engine's cylinder during the exhaust period
The inlet value of a four stroke cycle I.C engine remains open for nearly
180°
125°
235°
200°
The minimum cranking speed in case of petrol engine is about
Half the operating speed
One fourth of operating speed
250 - 300 rpm
60 - 80 rpm
Diesel fuel, compared to petrol is
Less difficult to ignite
Just about the same difficult to ignite
More difficult to ignite
Highly ignitable
The specific fuel consumption per B.P. hour for a diesel engine is about
0.2 kg
0.25 kg
0.3 kg
0.35 kg
The accumulation of carbon in a cylinder results in increase of
Clearance volume
Volumetric efficiency
Ignition time
Effective compression ratio
A higher compression ratio causes
Pre-ignition
Increase in detonation
Acceleration in the rate of combustion
Any one of these
The _________ engines can work on very lean mixture of fuel.
Spark ignition
Compression ignition
Both (A) and (B)
None of these
A diesel engine, during suction stroke, draws
Air only
Diesel only
A mixture of diesel and air
None of these
Compression loss in I.C engines occurs due to
Leaking piston rings
Use of thick head gasket
Clogged air inlet slots
All of the above
The ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time is called
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Volumetric efficiency
The ignition quality of petrol is expressed by
Cetane number
Octane number
Calorific value
All of these
A carburettor is used to supply
Petrol, air and lubricating oil
Air and diesel
Petrol and lubricating oil
Petrol and air
Which of the following statement is correct regarding normal cetane?
It is a standard fuel used for knock rating of diesel engines
Its chemical name is normal hexadecane
It has long carbon chain structure
All of the above
The exhaust valve in a four stroke cycle petrol engine
Opens at 50° before bottom dead centre and closes at 15° after top dead centre
Opens at bottom dead centre and closes at top dead centre
Opens at 50° after bottom dead centre and closes at 15° before top dead centre
May open and close anywhere
In a naturally aspirated diesel engine, the air is supplied by
A supercharger
A centrifugal blower
A vacuum chamber
An injection tube
The normal heptane (C7H16) is given a rating of ________ octane number.
0
50
100
120
The two reference fuels used for cetane rating are
Cetane and iso-octane
Cetane and alpha-methyl naphthalene
Cetane and normal heptane
Cetane and tetra ethyl lead
The actual volume of fresh charge admitted in 4-stroke petrol engine is
Equal to stroke volume
Equal to stroke volume and clearance volume
Less than stroke volume
More than stroke volume
A heat engine utilises the
Calorific value of oil
Low heat value of
High heat value of oil
Mean heat value of oil
The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at
1500 rpm
750 rpm
3000 rpm
Any value independent of engine speed
The knocking in spark ignition engines can be reduced by
Retarding the spark
Increasing the engine speed
Both (A) and (B)
None of these
Air fuel ratio at which a petrol engine cannot work is
8 : 1
10 : 1
15 : 1
20 : 1 and less
A petrol engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
The specific fuel consumption per B.P. hour for a petrol engine is about
0.2 kg
0.25 kg
0.3 kg
0.35 kg
In a four stroke cycle petrol engine, the expansion
Starts at top dead centre and ends at bottom dead centre
Starts at 30° before top dead centre and ends at 50° before bottom dead centre
Starts at 30° after top dead centre and ends at 50° after bottom dead centre
May start and end anywhere
Combustion in compression ignition engines is
Homogeneous
Heterogeneous
Both (A) and (B)
Laminar