For the same compression ratio
Otto cycle is more efficient than the Diesel
Diesel cycle is more efficient than Otto
Both Otto and Diesel cycles are, equally efficient
Compression ratio has nothing to do with efficiency
Correct Answer :
A. Otto cycle is more efficient than the Diesel
Related Questions
If V₁ is the jet velocity and V₀ is the vehicle velocity, then the propulsive efficiency of a rocket is given by
[2(V₀/V₁)]/ [1 + (V₀/V₁)²]
(V₀/V₁)/ [1 + (V₀/V₁)²]
V₀/(V₀ + V₁)
V₁/(V₀ + V₁)
Which one of the following engines will have heavier flywheel than the remaining ones?
30 kW four-stroke petrol engine running at 1500 r.p.m.
30 kW two-stroke petrol engine running at 1500 r.p.m.
30 kW two-stroke diesel engine running at 750 r.p.m.
30 kW four-stroke diesel engine running at 750 r.p.m.
The pressure and temperature at the end of compression stroke in a petrol engine are of the order of
4-6 kg/cm² and 200-250°C
6-12 kg/cm² and 250-350°C
12-20 kg/cm² and 350-450°C
20-30 kg/cm² and 450-500°C
All heat engines utilize
Low heat value of oil
High heat value of oil
Net calorific value of oil
Calorific value of fuel
Which of the following is the lightest and most volatile liquid fuel?
Diesel
Kerosene
Fuel oil
Gasoline
The turbine of the turboprop engine is __________ that of the turbojet engine.
Same as
Smaller than
Bigger than
None of these
The brake power is the power available
In the engine cylinder
At the crank shaft
At the crank pin
None of these
Which of the following fuel detonates readily?
Benzene
Iso-octane
Normal heptane
Alcohol
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 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
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
A diesel engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
The pressure at the end of compression, in petrol engines, is approximately
10 bar
20 bar
25 bar
35 bar
A stoichiometric air-fuel ratio is
Chemically correct mixture
Lean mixture
Rich mixture for idling
Rich mixture for over loads
The theoretically correct air fuel ratio for petrol engine is of the order of
6 : 1
9 : 1
12 : 1
15 : 1
Supercharging is essential in
Diesel engines
Gas turbines
Petrol engines
Aircraft engines
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
A 5 BHP engine running at full load would consume diesel of the order of
0.3 kg/hr
1 kg/hr
3 kg/hr
5 kg/hr
The expansion of fuel in a four stroke cycle diesel engine
Starts at 15° before top dead centre and ends at 30° after top dead centre
Starts at top dead centre and ends at 30° after top dead centre
Starts at 15° after top dead centre and ends at 30° before bottom dead centre
May start and end anywhere
A petrol engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the
Exhaust will be smoky
Piston rings would stick into piston grooves
Engine starts overheating
Scavenging occurs
The inlet value of a four stroke cycle I.C engine remains open for nearly
180°
125°
235°
200°
Flash point of fuel oil is
Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
Temperature at which it solidifies or congeals
Temperature at which it catches fire without external aid
Indicated by 90% distillation temperature, i.e. when 90% of sample oil has distilled off
In a naturally aspirated diesel engine, the air is supplied by
A supercharger
A centrifugal blower
A vacuum chamber
An injection tube
The volumetric efficiency of a well designed engine may be
30 to 40 %
40 to 60 %
60 to 70 %
75 to 90 %
The air-fuel ratio of the petrol engine is controlled by
Fuel pump
Governor
Injector
Carburettor
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
The higher combustion chamber wall temperature in compression ignition engines will _________ knocking tendency.
Increase
Reduce
Not effect
None of these
Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to
Cylinder walls being too hot
Overheated spark plug points
Red hot carbon deposits on cylinder walls
Any one of these
Pick up the false statement
Thermal efficiency of diesel engine is about 34%
Theoretically correct mixture of air and petrol is approximately 15:1
High speed compression engines operate on dual combustion cycle
S.I. engines are quality governed engines