ME-501 Internal Combustion Engines - May 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDefine volumetric efficiency of an I.C. Engines. What are the factors affecting volumetric efficiency?
   How to answer

   • Define volumetric efficiency as ratio of actual air intake to swept volume
   • List factors: engine speed, throttle opening, valve timing, intake/exhaust design, compression ratio, ambient conditions
   • Explain effect of each factor briefly
2. 7 Marks
   bA diesel engine has a compression ratio of 15 and heat addition at constant pressure takes place at 6% of stroke. Find the air standard efficiency of the cycle.
   How to answer

   • Identify cycle as Diesel cycle with r = 15
   • Determine cut-off ratio from 6% of stroke
   • Apply air-standard Diesel efficiency formula
   • Compute numerical value of efficiency
3. 7 Marks
   aWhat is heat balanced sheet? How it is prepared?
   How to answer

   • Define heat balance sheet and its purpose
   • List heat distribution heads: useful work, cooling, exhaust, radiation
   • Describe test procedure and preparation method
4. 7 Marks
   bWhat is ignition lag? Discuss the effect of engine variables on ignition lag.
   How to answer

   • Define ignition lag / delay period
   • Distinguish physical and chemical lag
   • Discuss engine variables: compression ratio, temperature, pressure, fuel, mixture, speed
5. 7 Marks
   aDiscuss the desirable characteristics of combustion chamber design for spark ignition engines.
   How to answer

   • List requirements: compactness, turbulence, spark plug location, cooling
   • Explain knock-free high compression operation
   • Discuss surface-to-volume and scavenging aspects
6. 7 Marks
   bHow does a flame propagate? Discuss the factors affecting the flame speed.
   How to answer

   • Describe flame front propagation mechanism
   • Define laminar and turbulent flame speed
   • Discuss factors: fuel-air ratio, temperature, pressure, turbulence, engine speed
7. 7 Marks
   aCompare the phenomenon of knock in SI and CI engines.
   How to answer

   • Define knock in SI and CI engines
   • Compare cause, timing, effects on pressure
   • Tabulate differences in fuel, compression, control
8. 7 Marks
   bExplain the various stages of combustion in compression ignition engines.
   How to answer

   • List four stages: ignition delay, uncontrolled, controlled, after burning
   • Explain pressure-crank angle features of each
   • Include diagram of combustion stages
9. 7 Marks
   aWhat is the function of a fuel injection system? Explain any one system with the help of a neat sketch.
   How to answer

   • List functions: metering, atomization, timing, distribution
   • Select one system e.g. common rail / individual pump
   • Explain working with neat sketch and components
10. 7 Marks
    bWith the help of a neat sketch explain the working principle of a simple carburetor.
    How to answer

    • Describe venturi, float chamber, jets and throttle
    • Explain air-fuel mixing and carburetion principle
    • Provide neat labelled sketch of simple carburetor
11. 7 Marks
    aWhat are the desirable characteristics of SI and CI engine fuels?
    How to answer

    • List SI fuel needs: volatility, octane number, gum content
    • List CI fuel needs: cetane number, viscosity, volatility
    • Summarize desirable properties for each
12. 7 Marks
    bExplain how hydrogen fuel is used in I.C. engines?
    How to answer

    • Mention hydrogen properties as fuel
    • Describe storage, supply and combustion modifications
    • Discuss advantages, challenges and emissions
13. 7 Marks
    aDescribe with the neat sketch different methods of supercharging.
    How to answer

    • Define supercharging purpose
    • Describe mechanical, turbo and exhaust-driven methods
    • Provide neat sketches of arrangements
14. 7 Marks
    bExplain the effect of supercharging on the performance of the engine.
    How to answer

    • Explain increased air density and power output
    • Discuss effects on fuel consumption, knock, thermal load
    • Summarize merits and limitations
15. 14 Marks
    Write short note on any three:

    1. a)Knock inhibitors
    2. b)Alternate fuels for SI and CI engines
    3. c)Cooling of SI and CI engines
    4. d)Theory of carburetion
    5. e)Cylinder arrangement
    How to answer

    • Introduce any three chosen topics briefly
    • Give definition, principle and relevance to IC engines
    • Conclude with applications or significance