If the temperature of intake air in internal combustion engine increases, then its efficiency will
Remain same
Decrease
Increase
None of these
Correct Answer :
B. Decrease
Related Questions
The pressure inside the cylinder is _________ the atmospheric pressure during the exhaust stroke.
Equal to
Below
Above
None of these
The loud pulsating noise heard within the cylinder of an internal combustion engine is known as
Detonation
Turbulence
Pre-ignition
Supercharging
The reflectivity depends upon
Geometry of the reflector
Energy of neutrons
Properties of the reflector
All of these
In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the
Beginning of suction stroke
End of suction stroke
Beginning of exhaust stroke
End of exhaust stroke
During idling, a petrol engine requires _________ mixture.
Lean
Rich
Chemically correct
None of these
Which of the following fuel has little tendency towards detonation?
Benzene
Iso-octane
Normal heptane
Alcohol
Which of the following is false statement? Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following
Piston ring and cylinder wear
Formation of hard coating on piston skirts
Oil sludge in the engine crank case
Detonation
Scavenging is usually done to increase
Thermal efficiency
Speed
Power output
Fuel consumption
The firing order in an I.C. engine depends upon
Arrangement of the cylinders
Design of crankshaft
Number of cylinders
All of these
Which of the following statement is correct regarding normal cetane?
It is a standard fuel used for knock rating of diesel engines
Its chemical name is normal hexadecane
It has long carbon chain structure
All of the above
In a four stroke cycle engine, the sequence of operations is
Suction, compression, expansion and exhaust
Suction, expansion, compression and exhaust
Expansion, compression, suction and exhaust
Compression, expansion, suction and exhaust
In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have
Low density
Low temperature
Long ignition delay
All of these
Air fuel ratio for idling speed of a petrol engine is approximately
1 : 1
5 : 1
10 : 1
15 : 1
The effective inhibitor of pre-ignition is
Alcohol
Water
Lead
None of these
Which of the following statement is wrong?
A four stroke cycle engine develops twice the power as that of a two stroke cycle engine
For the same power developed, a four stroke cycle engine is lighter, less bulky and occupies less floor area
The petrol engines are costly than diesel engines
All of the above
Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged?
Yes
No
To some extent
Unpredictable
The delay period in compression ignition engines depends upon
Temperature and pressure in the cylinder at the time of injection
Nature of the fuel mixture strength
Relative velocity between the fuel injection and air turbulence pressure of residual gases
All of the above
Diesel as compared to petrol is
Highly ignitable
More difficult to ignite
Less difficult to ignite
None of these
The turbine of the turboprop engine is __________ that of the turbojet engine.
Same as
Smaller than
Bigger than
None of these
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
For the same power developed in I.C. engines, the cheaper system is
Naturally aspirated
Supercharged
Centrifugal pump
Turbo charger
The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
Net efficiency
Efficiency ratio
Relative efficiency
Overall efficiency
The thermal efficiency of petrol and gas engines is about
15 %
30 %
50 %
70 %
If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the percentage increase in efficiency will be
2 %
4 %
8 %
14 %
The specific fuel consumption per BH hour for a petrol engine is approximately
0.15 kg
0.2 kg
0.25 kg
0.3 kg
The pressure at the end of compression, in diesel engines, is approximately
10 bar
20 bar
25 bar
35 bar
A diesel engine has
1 valve
2 valves
3 valves
4 valves
The ratio of the brake power to the indicated power is called
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Volumetric efficiency
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 ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called
Mechanical efficiency
Overall efficiency
Volumetric efficiency
Relative efficiency