Which of the following is false statement? Some of the methods used to reduce diesel smoke are as follows
Using additives in the fuel
Increasing the compression ratio
Adherence to proper fuel specification
Avoidance of overloading
Correct Answer :
B. Increasing the compression ratio
Related Questions
In a typical medium speed, 4-stroke cycle diesel engine
Fuel injection starts at 10° before to dead center and ends at 20° after tor dead center
Fuel injection starts at top dead center and ends at 20° after top dead center
Fuel injection starts at just before top dead center and ends just after top dead center
May start and end anywhere
The probability of knocking in diesel engines is increased by
High self ignition temperature
Low volatility
Higher viscosity
All of these
The effective inhibitor of pre-ignition is
Alcohol
Water
Lead
None of these
Diesel engine can work on very lean air fuel ratio of the order of 30: 1. A petrol engine can also work on such a lean ratio provided
It is properly designed
Best quality fuel is used
Cannot work as it is impossible
Flywheel size is proper
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
Which of the following does not relate to a compression ignition engine?
Fuel pump
Fuel injector
Governor
Carburettor
Most high speed compression engines operate on
Diesel cycle
Otto cycle
Dual combustion cycle
Special type of air cycle
In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.
Equal to
Below
Above
None of these
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
Which of the following medium is compressed in a Diesel engine cylinder?
Air alone
Air and fuel
Air and lub oil
Fuel alone
In a four stroke cycle petrol engine, the compression
Starts at 40° after bottom dead centre and ends at 30° before top dead centre
Starts at 40° before bottom dead centre and ends at 30° after bottom dead centre
Starts at bottom dead centre and ends at top dead centre
May start and end anywhere
The air-fuel ratio in petrol engines is controlled by
Controlling valve opening/closing
Governing
Injection
Carburetion
The frictional power (F.P.) is given by
F.P. = B.P. - I.P.
F.P. = I.P. - B.P.
F.P. = B.P./I.P.
F.P. = I.P./B.P.
The thermal efficiency of petrol and gas engines is about
15 %
30 %
50 %
70 %
All heat engines utilize
Low heat value of oil
High heat value of oil
Net calorific value of oil
Calorific value of fuel
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
Which is more viscous lube oil?
SEA 30
SAE 50
SAE 70
SAE 80
The inlet valve of a four stroke cycle internal combustion engine remains open for
130°
180°
230°
270°
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
The volumetric efficiency of a well designed engine may be
30 to 40 %
40 to 60 %
60 to 70 %
75 to 90 %
The fuel in diesel engine is normally injected at pressure of
5-10 kg/cm²
20-25 kg/cm²
60-80 kg/cm²
90-130 kg/cm²
Supercharging is the process of
Supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere
Providing forced cooling air
Injecting excess fuel for raising more loads
Supplying compressed air to remove combustion products fully
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
Fuel oil consumption guarantees for I .C. engine are usually based on
Low heat value of oil
High heat value of oil
Net calorific value of oil
Calorific value of fuel
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
A diesel engine as compared to petrol engine (both running and rated load) is
More efficient
Less efficient
Equally efficient
Other factors will decide it
Which of the following is the lightest and most volatile liquid fuel?
Diesel
Kerosene
Fuel oil
Gasoline
A gas engine has a swept volume of 300 cm3 and clearance volume of 25 cm3. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is
248 cm3
252 cm3
264 cm3
286 cm3
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
A carburettor is used to supply
Petrol, air and lubricating oil
Air and diesel
Petrol and lubricating oil
Petrol and air