Gaseous fuel guarantees are based on
Calorific value of oil
Low heat value of oil
High heat value of oil
Mean heat value of oil
Correct Answer :
B. Low heat value of oil
Related Questions
The rating of a diesel engine, with increase in air inlet temperature, will
Increase linearly
Decrease linearly
Increase parabolically
Decrease parabolically
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
The increase of cooling water temperature in petrol engine will __________ the knocking tendency.
Not effect
Decrease
Increase
None of these
In order to eliminate knocking in compression ignition engines, there should be
Short delay period
Late auto-ignition
Low compression ratio
High self ignition temperature of fuel
In a four stroke cycle diesel engine, the compression
Starts at 40° after bottom dead centre and ends at 10° before top dead centre
Starts at 40° before top dead centre and ends at 40° after top dead centre
Starts at top dead centre and ends at 40° before bottom dead centre
May start and end anywhere
Engine pistons are usually made of aluminium alloy because it
Is lighter
Wear is less
Absorbs shocks
Is stronger
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
A diesel engine has
One valve
Two valves
Three valves
Four valves
Which of the following fuel detonates readily?
Benzene
Iso-octane
Normal heptane
Alcohol
In a diesel engine, the fuel is ignited by
Spark
Injected fuel
Heat resulting from compressing air that is supplied for combustion
Ignition
The air standard efficiency of an I.C. engine depends on
Fuel used
Speed of engine
Compression ratio
None of these
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
A diesel engine is _________ as compared to petrol engine, both running at rated load.
Equally efficient
Less efficient
More efficient
None of these
The injector nozzle of a compression ignition engine is required to inject fuel at a sufficiently high pressure in order to
Inject fuel in a chamber of high pressure at the end of compression stroke
Inject fuel at a high velocity to facilitate atomisation
Ensure that penetration is not high
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
A heat engine utilises the
Calorific value of oil
Low heat value of
High heat value of oil
Mean heat value of oil
The mechanical efficiency (ηm) of the engine is given by
ηm = B.P/I.P
ηm = I.P/B.P
ηm = (B.P × I.P)/100
None of these
The air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is
More
Less
Same
May be more or less depending on engine capacity
Iso-octane (C8H18) has octane number of
0
50
100
120
In a cycle, the spark lasts roughly for
1 sec
0.1 sec
0.01 sec
0.001 sec
The ratio of the brake power to the indicated power is called
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Volumetric efficiency
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
In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will _________ the knocking tendency.
Not effected
Decrease
Increase
None of these
For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of
9 : 1
12 : 1
15 : 1
18 : 1
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
An engine indicator is used to determine the following
Speed
Temperature
Volume of cylinder
m.e.p. and I.H.P.
In a naturally aspirated diesel engine, the air is supplied by
A supercharger
A centrifugal blower
A vacuum chamber
An injection tube
Which of the following statement is correct?
Compression ratio for petrol engines varies from 6 to 10
Higher compression ratio in diesel engines results in higher pressures
Petrol engines work on Otto cycle
All of the above
It the temperature of intake air in IC engines is lowered, then its efficiency will
Increase
Decrease
Remain same
Increase up to certain limit and then decrease
The scavenging efficiency of a four stroke cycle diesel engine is
Below 50%
Between 50 and 85%
Between 85 and 95%
Between 95 and 100%