Thermal Engineering 12

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Objective Questions and Answer: Thermal Engineering 12

Subject: Thermal Engineering 12

Part 12: Objective questions and answers of Thermal Engineering

 

Q1. The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft

a) 10

b) 1

c) 2

d) 4

 

Q2. In a diesel engine, the fuel is ignited by

a) Spark

b) Injected fuel

c) Heat resulting from compressing air that is supplied for combustion

d) Ignition

 

Q3. Scavenging air in diesel engine means

a) Air used for combustion sent under pres-sure

b) Forced air for cooling cylinder

c) Burnt air containing products of combustion

d) Air used for forcing burnt gases out of engine's cylinder during the exhaust period

 

Q4. Supercharging is the process of

a) Supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere

b) Providing forced cooling air

c) Injecting excess fuel for raising more load

d) Supplying compressed air to remove combustion products fully

 

Q5. Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged?

a) Yes

b) No

c) To some extent

d) Unpredictable

 

Q6. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called

a) Net efficiency

b) Efficiency ratio

c) Relative efficiency

d) Overall efficiency

 

Q7. Compression ratio of LC. Engines is

a) The ratio of volumes of air in cylinder before compression stroke and after compression stroke

b) Volume displaced by piston per stroke and clearance volume in cylinder

c) Ratio of pressure after compression and before compression

d) Swept volume/cylinder volume

 

Q8. The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is

a) Same

b) Less

c) More

d) More or less depending on power rating

 

Q9. The calorific value of gaseous fuels is expressed in terms of

a) Kcal

b) Kcal/kg

c) Kcal/m^2

d) Kcal/ m^3

 

Q10. If the intake air temperature of I.C. engine increases, its efficiency will

a) Increase

b) Decrease

c) Remain same

d) Unpredictable

 

Q11. All heat engines utilize

a) Low heat value of oil

b) High heat value of oil

c) Net claorific value of oil

d) Calorific value of fuel

 

Q12. An engine indicator is used to determine the following

a) Speed

b) Temperature

c) Volume of cylinder

d) M.e.p. And I.H.P.

 

Q13. Fuel oil consumption guarantees for I .C. Engine are usually based on

a) Low heat value of oil

b) High heat value of oil

c) Net calorific value of oil

d) Calorific value of fuel

 

Q14. If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the %age increase in efficiency will be

a) 2%

b) 4%

c) 8%

d) 14%

 

Q15. In case of gas turbines, the gaseous fuel consumption guarantees are based on

a) High heat value

b) Low heat value

c) Net calorific value

d) Middle heat value

 

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

a) Opens at 20° before top dead center and closes at 35° after the bottom dead center

b) Opens at top dead center and closes at bottom dead center

c) Opens at 10° after top dead center and closes 20° before the bottom dead center

d) May open or close anywhere

 

Q17. The pressure and temperature at the end of compression stroke in a petrol engine are of the order of

a) 4 – 6 kg/cm2 and 200 – 250°C

b) 6 – 12 kg/cm2 and 250 – 350°C

c) 12 – 20 kg/cm2 and 350 – 450°C

d) 20 – 30 kg/cm2 and 450 – 500°C

 

Q18. The pressure at the end of compression in the case of diesel engine is of the order of

a) 6 kg/cm

b) 35kg/cmz

c) 20 kg/cmz

d) 27.5 kg/cmz

 

Q19. The maximum temperature in the I.C. engine cylinder is of the order of

a) 500- 1000°C

b) 1000- 1500°C

c) 1500-2000°C

d) 2000-2500°C

 

Q20. The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will

a) Increase

b) Decrease

c) Be independent

d) May increase or decrease depending on other factors

 

Part 12: Objective questions and answers of Thermal Engineering

 

Q1. Answer: c

Q2. Answer: c

Q3. Answer: d

Q4. Answer: a

Q5. Answer: b

Q6. Answer: c

Q7. Answer: a

Q8. Answer: c

Q9. Answer: d

Q10. Answer: b

Q11. Answer: a

Q12. Answer: d

Q13. Answer: b

Q14. Answer: d

Q15. Answer: b

Q16. Answer: a

Q17. Answer: b

Q18. Answer: b

Q19. Answer: d

Q20. Answer: b

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