250+ TOP MCQs on Diesel Engine Types and their Applications – II and Answers

Power Plant Engineering Multiple Choice Questions on “Diesel Engine Types and their Applications – II”.

1. The reference fuels for knock rating of spark ignition engines would include __________
a) normal octane and aniline
b) iso-octane and normal hexane
c) iso-octane and alpha-methyl naphthalene
d) normal heptane and iso-octane
Answer: d
Clarification: The reference fuels for knock rating of spark ignition engines would include normal heptane and iso-octane.

2. What is the purpose of testing an internal combustion engine?
a) to conform the data used in design, the validity of which may be doubtful
b) to satisfy the customer regarding the performance of the engine
c) to determine the information, which cannot be obtained by calculations
d) all of the mentioned
Answer: d
Clarification: The purpose of testing an internal combustion engine is to conform the data used in design, the validity of which may be doubtful; to satisfy the customer regarding the performance of the engine & to determine the information, which cannot be obtained by calculations.

3. Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to __________
a) overheated spark plug points
b) red hot carbon deposits on cylinder walls
c) cylinder walls being too hot
d) any of the mentioned
Answer: d
Clarification: Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to either overheated spark plug points, red hot carbon deposits on cylinder walls, & cylinder walls being too hot.

4. The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be __________
a) 20%
b) 25%
c) 50%
d) 55%
Answer: c
Clarification: The Thermal efficiency of a standard Otto cycle for a compression ratio r is given by,
N = 1 – (1/r1.4-1).

5. The fuels in order of decreasing knock tendency for spark ignition engines are __________
a) Paraffin, aromatic, napthene
b) Paraffin, napthene, aromatic
c) Napthene, aromatics, paraffin
d) Napthene, paraffin, aromatic
Answer: b
Clarification: The fuels in order of decreasing knock tendency for spark ignition engines are Paraffin, napthene, aromatic.

6. In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.
a) equal to
b) below
c) above
d) middle
Answer: b
Clarification: In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is below the atmospheric pressure.

7. Solid fuel fabricated into various small shapes, which are assembled to form fuel elements, is in the form of __________
a) pallets
b) plates
c) pins
d) all of the mentioned
Answer: d
Clarification: Solid fuel fabricated into various small shapes are of the form of pallets, plates, pins, etc.

8. A diesel engine is __________ as compared to petrol engine, both running at rated load.
a) equally efficient
b) more efficient
c) less efficient
d) all of the mentioned
Answer: b
Clarification: A diesel engine is more efficient as compared to petrol engine, both running at rated load.

9. A higher compression ratio causes __________
a) increase in detonation
b) pre-ignition
c) an acceleration in the rate of combustion
d) any one of the mentioned
Answer: d
Clarification: A higher compression ratio causes increased detonation, increased rate of combustion & pre-ignition.

10. Which one of the following event would reduce volumetric efficiency of a vertical compression ignition engine?
a) inlet valve closing before bottom dead centre
b) inlet valve closing after bottom dead centre
c) inlet valve opening before top dead centre
d) exhaust valve closing after top dead centre
Answer: a
Clarification: Inlet valve closing before bottom dead centre would reduce the volumetric efficiency of a vertical compression ignition engine.