The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is
Same
Less
More
More or less depending on power rating
Correct Answer :
C. More
Related Questions
A higher compression ratio causes
Pre-ignition
Increase in detonation
Acceleration in the rate of combustion
Any one of these
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
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
During idling, a petrol engine requires _________ mixture.
Lean
Rich
Chemically correct
None of these
Crankcase explosion in I.C. engines usually occurs as
First a mild explosion followed by a bi explosion
First a big explosion followed by a mil explosion
Both mild and big explosions occurs simultaneously
Never occurs
Antiknock for compression ignition engines is
Napthene
Tetra ethyl lead
Amyl nitrate
Hexadecane
The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be
Higher
Lower
Remain unaffected
None of the above
The higher combustion chamber wall temperature in compression ignition engines will _________ knocking tendency.
Increase
Reduce
Not effect
None of these
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 inlet valve of a four stroke cycle internal combustion engine remains open for
130°
180°
230°
270°
If the intake air temperature of I.C. engine increases, its efficiency will
Increase
Decrease
Remain same
None of these
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 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
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
Diesel fuel, compared to petrol is
Less difficult to ignite
Just about the same difficult to ignite
More difficult to ignite
Highly ignitable
If V₁ is the jet velocity and V₀ is the vehicle velocity, then propulsive efficiency of a turbojet engine is
V₁/(V₀ + V₁)
V₀/(V₀ + V₁)
2V₀/(V₀ + V₁)
2V₁/(V₀ + V₁)
The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be
25 %
50 %
70 %
100 %
Engine pistons are usually made of aluminium alloy because it
Is lighter
Wear is less
Absorbs shocks
Is stronger
The compression ignition engines are governed by
Hit and miss governing
Qualitative governing
Quantitative governing
Combination of (B) and (C)
The magneto in an automobile is basically
Transformer
D.C. generator
Capacitor
Magnetic circuit
A petrol engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
Combustion in compression ignition engines is
Homogeneous
Heterogeneous
Both (A) and (B)
Laminar
Morse test is used to determine the I.P. of a
Single cylinder petrol engine
Four stroke engine
Single cylinder diesel engine
Multi cylinder engine
Pick up the wrong statement
2-stroke engine can run in any direction
In 4-stroke engine, a power stroke is obtained in 4-strokes
Thermal efficiency of 4-stroke engine is more due to positive scavenging
Petrol engines occupy more space than diesel engines for same power output
The ignition quality of diesel oil is expressed by
Cetane number
Octane number
Calorific value
None of these
The pressure at the end of compression in the case of diesel engine is of the order of
6 kg/cm
12 kg/cm
20 kg/cm
35 kg/cm
An engine indicator is used to determine the following
Speed
Temperature
Volume of cylinder
m.e.p. and I.H.P.
Which of the following medium is compressed in a Diesel engine cylinder?
Air alone
Air and fuel
Air and lub oil
Fuel alone
Which one of the following event would reduce volumetric efficiency of a vertical compression ignition engine?
Inlet valve closing after bottom dead centre
Inlet valve closing before bottom dead centre
Inlet valve opening before top dead centre
Exhaust valve closing after top dead centre
A stoichiometric air-fuel ratio is
Chemically correct mixture
Lean mixture
Rich mixture for idling
Rich mixture for over loads