The increase of efficiency of a compression ignition engine, as the load decreases, is due to
Higher maximum temperature
Qualitative governing
Quantitative governing
Hit and miss governing
Correct Answer :
B. Qualitative governing
Related Questions
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 petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a
Fuel pump
Fuel injector
Spark plug
None of these
The probability of knocking in diesel engines is increased by
High self ignition temperature
Low volatility
Higher viscosity
All of these
Scavenging is usually done to increase
Thermal efficiency
Speed
Power output
Fuel consumption
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
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
In a typical medium speed 4-stroke cycle diesel engine the inlet valve
Opens at 20° before top dead center and closes at 35° after the bottom dead center
Opens at top dead center and closes at bottom dead center
Opens at 10° after top dead center and closes 20° before the bottom dead center
May open or close anywhere
The ignition quality of diesel oil is expressed by
Cetane number
Octane number
Calorific value
None of these
Which of the following is not an interns combustion engine?
2-stroke petrol engine
4-stroke petrol engine
Diesel engine
Steam turbine
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
Number of working strokes per min. for a two stroke cycle engine is _________ the speed of the engine in r.p.m.
Equal to
One-half
Twice
Four-times
The reference fuels for knock rating of spark ignition engines would include
Iso-octane and alpha-methyl naphthalene
Normal octane and aniline
Isooctane and normal hexane
Normal heptane and isooctane
The process of breaking up or a liquid into fine droplets by spraying is called
Vaporisation
Carburetion
Ionisation
Atomisation
A petrol engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
Diesel as compared to petrol is
Highly ignitable
More difficult to ignite
Less difficult to ignite
None of these
Combustion in compression ignition engines is
Homogeneous
Heterogeneous
Both (A) and (B)
Laminar
The thermal efficiency of petrol and gas engines is about
15 %
30 %
50 %
70 %
The air-fuel ratio in petrol engines is controlled by
Controlling valve opening/closing
Governing
Injection
Carburetion
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 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 increase of cooling water temperature in petrol engine will __________ the knocking tendency.
Not effect
Decrease
Increase
None of these
The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is
Same
More
Less
Less or more depending on operating conditions
Most high speed compression engines operate on
Diesel cycle
Otto cycle
Dual combustion cycle
Special type of air cycle
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
In a four stroke cycle petrol engine, the inlet valve
Opens at top dead centre and closes at bottom dead centre
Opens at 20° before top dead centre and closes at 40° after bottom dead centre
Opens at 20° after top dead centre and closes at 20° before bottom dead centre
May open or close anywhere
The _________ engines can work on very lean mixture of fuel.
Spark ignition
Compression ignition
Both (A) and (B)
None of these
The thermodynamic cycle on which the petrol engine works, is
Otto cycle
Joule cycle
Rankine cycle
Stirling cycle
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
The maximum temperature in the I.C. engine cylinder is of the order of
500-1000°C
1000-1500°C
1500-2000°C
2000-2500°C
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