Q1. For the same compression ratio and heat input,
the efficiency of an Otto cycle engine as
compared to diesel engine is
(a) more
(b) less
(c) equal
(d) none of these
Ans. a
Sol.
More
Q2. Diesel cycle efficiency is approach that of
(a) minimum
(b) maximum
(c) zero
(d) none of the above
Ans. c
Sol.
In conclusion, the efficiency of Diesel cycle can approach that of
Q3. The ratio of brake power to indicated power of
an I.C. engine is called as
(a) mechanical efficiency
(b) Thermal efficiency
(c) Volumetric efficiency
(d) Relative efficiency
Ans. a
Sol.
Q4. A two stroke engine has a speed of 750 rpm. A
four stroke engine having an identical cylinder
size running at 1500 rpm. The theoretical output
of the two stroke engine will be :
(a) twice that of the four stroke engine
(b) half that of the four stroke engine
(c) the same as that of the four stroke engine
(d) depend upon whether it is a CI or SI engine
Ans. c
Sol.
A two stroke engine has a speed of 750 rpm.
A four stroke engine having an identical cylinder size
running at 1500 rpm. The theoretical output of the two
stroke engine will be the same as that of the four stroke
engine.
Q5. For the same maximum pressure and heat input,
the most efficient cycle is
(a) Brayton
(b) Otto
(c) Diesel
(d) Dual
Ans. c
Sol.
Q6. In a two stroke cycle engine, the operations
namely suction, compression, expansion and
exhaust are completed in the number of
revolutions of crank shaft equal to
(a) Four
(b) Three
(c) Two
(d) One
Ans. d
Sol.
In-2 stroke engine, the working cycle is
completed in two strokes of the piston or one revolution
of the crankshaft.
Q7. For the same maximum pressure and
temperature of Otto, diesel and duel
combustion air standard cycles
(a) the compression ratios will be the same
(b) the heat supplied to the cycles will be the
same
(c) the air standard efficiency will have the same
value
(d) the heat rejected by the engine will be the
same
Ans. d
Sol.
For the same maximum pressure and
temperature of Otto cycle diesel and dual combustion
air standard cycles the heat rejected.
Q8. For same output, same speed and same
compression ratio, the thermal efficiency of a
two stroke cycle petrol engine as compared to
that for four stroke cycle petrol engine is
(a) more
(b) less
(c) same as long as compression ratio is same
(d) same as long as output is same
Ans. b
Sol.
The thermal efficiency of two stroke petrol
engine as compared to that of a four-stroke petrol
engine for same output, same speed and same
compression ratio is less.
Q9. Most of the high-speed compression engine
operate on
(a) Diesel engine
(b) Otto cycle
(c) dual combustion cycle
(d) special type of air cycle
Ans. c
Sol.
Most of the high speed compression engine
operates on dual combustion cycle.
Q10. Lean mixture in an automobile is required
during :
(a) Idling
(b) Starting
(c) Accelerating
(d) Cruising
Ans. d
Sol.
Lean mixture in an automobile is required during cruising
OperationA/F ratio
Idling 12-12.5
Cruising/normal 16- 16.5
Maximum power 12-13
Starting 3-5