Thermal Engineering 15

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Objective Questions and Answer: Thermal Engineering 15

Subject: Thermal Engineering 15

Part 15: Objective questions and answers of Thermal Engineering


Q1. A diesel engine as compared to petrol engine (both running load) is

a) More efficient

b) Less efficient

c) Equally efficient

d) Unpredictable


Q2. The size of inlet valve engine in comparison to exhaust valve is

a) More

b) Less

c) Same

d) More/less depending on capacity of engine


Q3. In a cycle, the spark lasts roughly for

a) 1 sec

b) 0.1 sec

c) 0.01 sec

d) 0.001 sec


Q4. Which of the following is false statement: Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following

a) Piston ring and cylinder wear

b) Formation of hard coating on piston skirts

c) Oil sludge in the engine crank case

d) Detonation


Q5. Which of the following is false statement? Some of the methods used to reduce diesel smoke are as follows

a) Using additives in the fuel

b) Engine derating i.e. Reducing the maxi-mum flow of fuel

c) Increasing the compression ratio

d) Adherence to proper fuel specification


Q6. The fuel air ratio in a petrol engine fitted with suction carburetor, operating with dirty air filter as compared to clean filter will be

a) Higher

b) Lower

c) Remain unaffected

d) Unpredictable


Q7. Pick up the wrong statement about supercharging

a) Supercharging reduces knocking in diesel engines

b) There can be limited supercharging in petrol engines because of detonation

c) Supercharging at high altitudes is essential

d) Supercharging results in fuel economy


Q8. The actual volume of fresh charge admitted in 4-stroke petrol engine is

a) Equal to stroke volume

b) Equal to stroke volume and clearance volume

c) Less than stroke volume

d) More than stroke volume


Q9. The magneto in an automobile is basically

a) Transformer

b) D.c. Generator

c) Capacitor

d) Magnetic circuit


Q10. The reason for supercharging in any engine is to

a) Increase efficiency

b) Increase power

c) Reduce weight and bulk for a given out-put

d) Effect fuel economy


Q11. The operation of forcing additional air under pressure in the engine cylinder is known as

a) Scavenging

b) Turbulence

c) Supercharging

d) Pre-ignition


Q12. Supercharging is essential in

a) Diesel engines

b) Gas turbines

c) Petrol engines

d) Aircraft engines


Q13. The minimum cranking speed in case of petrol engine is about

a) Half the operating speed

b) One-fourth of operating speed

c) 250-300 rpm

d) 60-80 rpm


Q14. In a typical medium speed 4 stroke cycle diesel engine

a) Exhaust valve opens at 35° before bot-tom dead center and closes at 20° after top dead center

b) Exhaust valve opens at bottom 'dead center and closes at top dead center

c) Exhaust valve opens just after bottom dead center and closes just before top dead center

d) May open and close anywhere


Q15. Flash point of fuel oil is

a) Minimum temperature to which1 oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame

b) Temperature at which it solidifies or congeals

c) Temperature at which it catches fire without external aid

d) Indicated by 90% distillation temperature, i.e. When 90% of sample oil has distilled off


Q16. The mean effective pressure obtained from engine indicator indicates the

a) Maximum pressure developed

b) Minimum pressure

c) Instantaneous pressure at any instant

d) Average pressure.


Q17. For the same power developed in I.C. engines, the cheaper system is

a) Naturally aspirated

b) Supercharged

c) Centrifugal pump

d) Turbo charger


Q18. Installation of supercharger on a four-cycle diesel engine can result in the following percentage increase in power

a) Upto 25%

b) Upto 35%

c) Upto 50%

d) Upto 100%.


Q19. Scavenging is usually done to increase

a) Thermal efficiency

b) Speed

c) Power output

d) Fuel consumption


Q20. Which of the following is the lightest and most volatile liquid fuel?

a) Diesel

b) Kerosene

c) Fuel oil

d) Gasoline


Part 15: Objective questions and answers of Thermal Engineering


Q1. Answer: a

Q2. Answer: b

Q3. Answer: c

Q4. Answer: d

Q5. Answer: c

Q6. Answer: a

Q7. Answer: d

Q8. Answer: c

Q9. Answer: b

Q10. Answer: c

Q11. Answer: c

Q12. Answer: d

Q13. Answer: d

Q14. Answer: a

Q15. Answer: a

Q16. Answer: d

Q17. Answer: b

Q18. Answer: d

Q19. Answer: c

Q20. Answer: d

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