The thermal efficiency of a petrol engine is _________ as compared to diesel engine.
Same
Less
More
None of these
Correct Answer :
B. Less
Related Questions
The following volume of air is required for consuming 1 litre of fuel by a four stroke engine
1 m3
5 m3
56 m3
910 m3
Scavenging is usually done to increase
Thermal efficiency
Speed
Power output
Fuel consumption
In a diesel engine, the duration between the time of injection and ignition, is known as
Pre-ignition period
Delay period
Period of ignition
Burning period
The object of providing masked inlet valve in the air passage of compression ignition engines is to
Enhance flow rate
Control air flow
Induce primary swirl
Induce secondary turbulence
A diesel engine has
1 valve
2 valves
3 valves
4 valves
Engine pistons are usually made of aluminium alloy because it
Is lighter
Wear is less
Absorbs shocks
Is stronger
Diesel as compared to petrol is
Highly ignitable
More difficult to ignite
Less difficult to ignite
None of these
The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in metres, N = Speed of engine in r.p.m., S = Spring balance reading in newtons, D = Dia. of brake drum in metres, and d = Dia. of rope in metres)
B.P = (Wl × 2πN)/60 watts
B.P = [(W - S) πDN]/60 watts
B.P = [(W - S) π (D + d) N]/60 watts
All of these
The normal heptane (C7H16) is given a rating of ________ octane number.
0
50
100
120
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 actual volume of fresh charge admitted in 4-stroke petrol engine is
Equal to stroke volume
Equal to stroke volume and clearance volume
Less than stroke volume
More than stroke volume
In a coil ignition system of petrol engines, a condenser is connected across the contact breaker in order to
Prevent sparking across the gap between the points
Cause more rapid break of the primary current, giving a higher voltage in the secondary circuit
Both (A) and (B)
None of the above
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
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
Which of the following is not an interns combustion engine?
2-stroke petrol engine
4-stroke petrol engine
Diesel engine
Steam turbine
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
The knocking tendency in compression ignition engines for a given fuel will be
Enhanced by decreasing compression ratio
Enhanced by increasing compression ratio
Dependent on other factors
None of the above
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 brake power is the power available
In the engine cylinder
At the crank shaft
At the crank pin
None of these
The ratio of the indicated thermal efficiency to the air standard efficiency is known as
Mechanical efficiency
Overall efficiency
Volumetric efficiency
Relative efficiency
Which of the following is the lightest and most volatile liquid fuel?
Diesel
Kerosene
Fuel oil
Gasoline
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
In a typical medium speed 4-stroke cycle diesel engine
Compression starts at 35° after bottom dead center and ends at top dead center
Compression starts at bottom dead center and ends at top dead center
Compression starts at 10° before bottom dead center and, ends just before top dead center
May start and end anywhere
The calorific value of gaseous fuels is expressed in terms of
kcal
kcal/kg
kcal/m²
kcal/m3
Air fuel ratio at which a petrol engine cannot work is
8 : 1
10 : 1
15 : 1
20 : 1 and less
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)
The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be
25 %
50 %
70 %
100 %
The thermodynamic cycle on which the petrol engine works, is
Otto cycle
Joule cycle
Rankine cycle
Stirling cycle
The increase of cooling water temperature in petrol engine will __________ the knocking tendency.
Not effect
Decrease
Increase
None of these
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