Gas & Diesel Power Plant – 50 MCQs with Answers

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Q1. Gas turbine works on which cycle?
A) Rankine cycle
B) Otto cycle
C) Brayton cycle
D) Carnot cycle
Ans: C

Q2. Diesel engine works on which cycle?
A) Otto cycle
B) Dual cycle
C) Diesel cycle
D) Rankine cycle
Ans: C

Q3. The efficiency of gas turbine is:
A) 10–15%
B) 20–25%
C) 30–35%
D) 40–50%
Ans: C

Q4. The efficiency of diesel power plant is about:
A) 10–15%
B) 25–35%
C) 35–45%
D) 50–60%
Ans: C

Q5. In gas turbine plant, the compressor is used to:
A) Increase pressure of air
B) Increase velocity of air
C) Decrease pressure of air
D) Reduce losses
Ans: A

Q6. The specific fuel consumption of diesel plant is about:
A) 0.1–0.2 kg/kWh
B) 0.2–0.3 kg/kWh
C) 0.4–0.6 kg/kWh
D) 1.0 kg/kWh
Ans: C

Q7. Which of the following is a constant pressure cycle?
A) Otto
B) Diesel
C) Brayton
D) Both B and C
Ans: D

Q8. Which of the following is a constant volume cycle?
A) Otto
B) Diesel
C) Brayton
D) Stirling
Ans: A

Q9. The main advantage of gas turbine is:
A) High efficiency
B) Low weight and compact size
C) Low operating cost
D) Easy fuel storage
Ans: B

Q10. The starting system of diesel engine is generally:
A) Battery and electric motor
B) Compressed air
C) Hand cranking
D) All of the above
Ans: D

Q11. The compression ratio of diesel engine is about:
A) 6–10
B) 10–20
C) 20–30
D) 30–40
Ans: B

Q12. The compression ratio of gas turbine is about:
A) 3–5
B) 6–10
C) 10–20
D) 20–30
Ans: B

Q13. The air-fuel ratio of diesel engine is:
A) 8:1 to 12:1
B) 14:1 to 20:1
C) 18:1 to 40:1
D) 40:1 to 60:1
Ans: C

Q14. In diesel engines, ignition takes place due to:
A) Spark plug
B) Compression heat
C) Carburetor
D) Magneto
Ans: B

Q15. Supercharging is used in diesel engines to:
A) Reduce temperature
B) Increase power output
C) Reduce fuel consumption
D) Decrease efficiency
Ans: B

Q16. Gas turbine blades are usually made of:
A) Mild steel
B) Aluminium alloy
C) Nickel-chromium alloy
D) Brass
Ans: C

Q17. The main disadvantage of gas turbine is:
A) High initial cost
B) Low part-load efficiency
C) More fuel requirement
D) All of the above
Ans: D

Q18. Diesel engines are:
A) Spark ignition
B) Compression ignition
C) Both A and B
D) None
Ans: B

Q19. The fuel used in gas turbine is:
A) Petrol
B) Diesel
C) Natural gas
D) All of the above
Ans: D

Q20. Diesel power plants are generally used as:
A) Base load
B) Peak load
C) Standby plants
D) Both B and C
Ans: D

Q21. The gas turbine efficiency can be improved by:
A) Intercooling
B) Reheating
C) Regeneration
D) All of the above
Ans: D

Q22. The air used in diesel engine is:
A) Pure oxygen
B) Normal atmospheric air
C) Hydrogen
D) Nitrogen
Ans: B

Q23. The speed of diesel engine is usually:
A) 100–500 rpm
B) 500–1000 rpm
C) 1000–1500 rpm
D) 1500–3000 rpm
Ans: C

Q24. The specific speed of gas turbine is:
A) Low
B) High
C) Moderate
D) None
Ans: B

Q25. The main parts of gas turbine are:
A) Compressor, combustor, turbine
B) Compressor, boiler, turbine
C) Boiler, condenser, turbine
D) Turbine, governor, generator
Ans: A

Q26. Diesel power plants are suitable for:
A) Small capacity
B) Large capacity
C) Medium capacity
D) None
Ans: A

Q27. The exhaust temperature of gas turbine is about:
A) 100–200°C
B) 200–400°C
C) 400–600°C
D) 800–1000°C
Ans: C

Q28. The fuel injection in diesel engine takes place:
A) Before compression
B) During compression
C) At the end of compression stroke
D) During exhaust stroke
Ans: C

Q29. The efficiency of modern gas turbine is about:
A) 20%
B) 25%
C) 35–40%
D) 50–60%
Ans: C

Q30. Which of the following is NOT a component of diesel plant?
A) Air filter
B) Fuel injector
C) Combustion chamber
D) Carburetor
Ans: D

Q31. The cooling of diesel engines is done by:
A) Water
B) Air
C) Both A and B
D) Oil only
Ans: C

Q32. The function of turbocharger in diesel engine is:
A) Cooling
B) Increasing intake pressure
C) Reducing fuel consumption
D) Reduce noise
Ans: B

Q33. The lubrication in diesel engine is done to:
A) Reduce friction
B) Remove heat
C) Increase efficiency
D) All of the above
Ans: D

Q34. The combustion in diesel engine is:
A) Homogeneous
B) Heterogeneous
C) Complete
D) None
Ans: B

Q35. The capacity of diesel power plants is generally:
A) <10 MW
B) 10–50 MW
C) 50–100 MW
D) >500 MW
Ans: A

Q36. The back work ratio in gas turbine is about:
A) 0.1
B) 0.2
C) 0.4–0.6
D) 0.8
Ans: C

Q37. The power to weight ratio is best in:
A) Gas turbine
B) Diesel engine
C) Steam turbine
D) Hydro turbine
Ans: A

Q38. The fuel consumption of diesel engine is:
A) More than steam
B) Less than gas turbine
C) High compared to nuclear
D) All of the above
Ans: D

Q39. The ignition temperature of diesel fuel is about:
A) 100°C
B) 200°C
C) 250–300°C
D) 500°C
Ans: C

Q40. The governor in diesel engine controls:
A) Fuel supply
B) Air supply
C) Exhaust
D) Coolant
Ans: A

Q41. Which cycle is used in jet engines?
A) Otto
B) Diesel
C) Brayton
D) Dual
Ans: C

Q42. Diesel plants have:
A) High starting time
B) Low starting time
C) Zero starting time
D) Infinite starting time
Ans: B

Q43. The efficiency of combined gas-steam cycle is about:
A) 20%
B) 40%
C) 55–60%
D) 70%
Ans: C

Q44. The fuel cost per kWh is maximum for:
A) Gas turbine plant
B) Diesel plant
C) Thermal plant
D) Hydro plant
Ans: B

Q45. The pressure ratio in gas turbine is usually:
A) 2–4
B) 4–10
C) 10–15
D) 15–20
Ans: B

Q46. The heat rate of diesel plant is about:
A) 2000–2500 kcal/kWh
B) 3000–3500 kcal/kWh
C) 4000–4500 kcal/kWh
D) 5000 kcal/kWh
Ans: C

Q47. Diesel engines are generally:
A) Four stroke
B) Two stroke
C) Both A and B
D) None
Ans: C

Q48. The reliability of diesel power plant is:
A) Low
B) Medium
C) High
D) Very low
Ans: C

Q49. The operation and maintenance cost is highest in:
A) Hydro plant
B) Nuclear plant
C) Diesel plant
D) Thermal plant
Ans: C

Q50. The gas turbine plant is suitable for:
A) Peak load
B) Base load
C) Both A and B
D) Standby
Ans: A