Questions set 55

Development of IC Engines

1.      In a Otto cycle engine, combustion occurs at
a) Constant pressure
b) Constant temperature
c) Constant volume
d) Constant heat
Answer: c
Explanation: Combustion process in a Otto cycle engine occurs at constant volume.

2.      In a Diesel cycle engine, combustion occurs at
a) Constant pressure
b) Constant temperature
c) Constant volume
d) Constant heat
Answer: a
Explanation: Combustion in a Diesel cycle engine occurs at constant pressure.

3.      Heat rejection in diesel cycle is at
a) Constant pressure
b) Constant volume
c) Constant temperature
d) None of the mentioned
Answer: b
Explanation: Heat rejection in diesel cycle occurs at constant volume.

4.      In a four stroke ic engine the number of strokes covered for one complete crankshaft revolution is
a) 4
b) 2
c) 1
d) 0.5
Answer: b
Explanation: For a 4 stroke engine, piston covers 2 strokes for one complete crankshaft revolution.

5.      Which stroke for a 4-stroke ic engine is considered as the working or power stroke
a) Suction stroke
b) Compression stroke
c) Expansion stroke
d) Exhaust stroke
Answer: c
Explanation: Expansion stroke is the working stroke.

6.      The valves of an ic engine are made to open and close slowly to
a) Increase the engine efficiency
b) Decrease the fuel consumption
c) Allow engine to cool in the meantime
d) Provide silent operation under high speed conditions
Answer: d
Explanation: The valves are made to open and close slowly to provide silent operation under high speed conditions.

7.      Which of these is not an assumption made in deriving the formula for air standard of Otto cycle
a) There is no heat loss during the cycle
b) The compression and expansion are isothermal
c) The heating and cooling strictly take place at constant volume
d) The suction and exhaust take place at atmospheric pressure
Answer: b
Explanation: Compression and expansion are assumed strictly adiabatic in a Otto cycle.

8.      Higher efficiency in Otto cycle can be achieved by
a) Increasing the compression ratio
b) Decreasing the compression ratio
c) Keeping the compression ratio constant
d) Efficiency does not depend on compression ratio
Answer: a
Explanation: Higher efficiency can be achieved by increasing the compression ratio.

9.      The expansion process in diesel engine is
a) Isothermal
b) Adiabatic
c) Isobaric
d) None of the mentioned
Answer: b
Explanation: Adiabatic expansion occurs in diesel cycle.

10.  In two-stroke cycle engines, what replaces valves of a four-stroke engine
a) Fins
b) Notches
c) Ports
d) Tubes
Answer: c
Explanation: Valves are replaced by ports in two-stroke cycle engines.