Thermal Engineering 13

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Objective Questions and Answer: Thermal Engineering 13

Subject: Thermal Engineering 13

Part 13: Objective questions and answers of Thermal Engineering


Q1. Pick up the wrong statement

a) 2-stroke engine can run in any direction

b) In 4-stroke engine, a power stroke is obtained in 4-strokes

c) Thermal efficiency of 4-stroke engine is more due to positive scavenging

d) Petrol engines occupy more space than diesel engines for same power output.


Q2. Combustion in compression ignition engines is

a) Homogeneous

b) Heterogeneous

c) Both (a) and (b)

d) Laminar


Q3. The fuel in diesel engine is normally injected at pressure of

a) 5-10 kg/cm^2

b) 20-25 kg/cm^2

c) 60-80 kg/cm^2

d) 90-130 kg/cm^2


Q4. The specific fuel consumption per BHP hour for diesel engine is approximately

a) 0.15 kg

b) 0.2 kg

c) 0.25 kg

d) 0.3 kg


Q5. The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed

a) 80°C

b) 120°C

c) 180°C

d) 240°C


Q6. Crankcase explosion in I.C. engines usually occurs as

a) First a mild explosion followed by a bi explosion

b) First a big explosion followed by a mil explosion

c) Both mild and big explosions occi simultaneously

d) Never occurs


Q7. Compression loss in I.C engines occurs due to

a) Leaking piston rings

b) Use of thick head gasket

c) Clogged air-inlet slots

d) All of the above.


Q8. The specific fuel consumption per BH hour for a petrol engine is approximately

a) 0.15 kg

b) 0.2 kg

c) 0.25 kg

d) 0.3kg


Q9. The air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is

a) More

b) Loss

c) Same

d) May be more or less depending on engine capacity


Q10. The inlet value of a four stroke cycle I.C engine remains open for nearly

a) 180°

b) 125°

c) 235°

d) 200°


Q11. Which of the following is not an interns combustion engine

a) 2-stroke petrol engine

b) 4-stroke petrol engine

c) Diesel engine

d) Steam turbine.


Q12. Pick up the false statement

a) Thermal efficiency of diesel engine i about 34%

b) Theoretically correct mixture of air am petrol is approximately 15 : 1

c) High speed compression engines operate on dual combustion cycle

d) S.I. engines are quality-governed engines.


Q13. If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the

a) Exhaust will be smoky

b) Piston rings would stick into piston grooves

c) Exhaust temperature will be high

d) Scavenging occurs.


Q14. The output of a diesel engine can be increased without increasing the engine revolution or size in following way

a) Feeding more fuel

b) Increasing flywheel size

c) Heating incoming air

d) Supercharging


Q15. It the temperature of intake air in IC engines is lowered, then its efficiency will

a) Increase

b) Decrease

c) Remain same

d) Increase upto certain limit and then decrease


Q16. In a typical medium speed 4-stroke cycle diesel engine

a) Compression starts at 35° after bottom dead center and ends at top dead center

b) Compression starts at bottom dead center and ends at top dead center

c) Compression starts at 10° before bottom dead center and, ends just before top dead center

d) May start and end anywhere


Q17. For the same compression ratio

a) Otto cycle is more efficient than the Diesel

b) Diesel cycle is more efficient than Otto

c) Both Otto and Diesel cycles are, equally efficient

d) Compression ratio has nothing to do with efficiency


Q18. The precess of breaking up or a liquid into fine droplets by spraying is called

a) Vaporisation

b) Carburetion

c) Ionisation

d) Atomisation.


Q19. As a result of detonation in an I.C. engine, following parameter attains very high value

a) Peak pressure

b) Rate of rise of pressure

c) Rate of rise of temperature

d) Peak temperature


Q20. Which of the following statements is correct?

a) All the irreversible engines have same efficiency

b) All the reversible engines have same efficiency

c) Both Rankine and Caront cycles have same efficiency between same temperature limits

d) All reversible engines working between same temperature limits have same efficiency


Part 13: Objective questions and answers of Thermal Engineering


Q1. Answer: d

Q2. Answer: b

Q3. Answer: d

Q4. Answer: b

Q5. Answer: c

Q6. Answer: a

Q7. Answer: d

Q8. Answer: c

Q9. Answer: b

Q10. Answer: c

Q11. Answer: d

Q12. Answer: d

Q13. Answer: d

Q14. Answer: d

Q15. Answer: a

Q16. Answer: a

Q17. Answer: a

Q18. Answer: d

Q19. Answer: c

Q20. Answer: d

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