ME-501 Internal Combustion Engines - Dec 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
   aHow the I.C. engines are classified? Draw a neat diagram of an I.C. engine and mark the important parts.
   How to answer

   • Basis of classification of I.C. engines
   • List of types under each basis
   • Neat labelled sketch of I.C. engine
   • Marking of important parts
2. 7 Marks
   bDefine volumetric efficiency applied to I.C. engines. What are the factors effecting the volumetric efficiency of Spark Ignition (S.I.) and Compression Ignition (C.I.) engine?
   How to answer

   • Definition of volumetric efficiency
   • Formula in terms of actual and swept volume
   • Factors affecting volumetric efficiency
   • Difference for S.I. vs C.I. engines
3. 7 Marks
   aDefine the following performance parameters of I.C. engine.

   1. i)Indicated Power (IP)
   2. ii)Mean effective pressure
   3. iii)Brake Power (BP)
   4. iv)Indicated thermal efficiency
   5. v)Mechanical efficiency
   How to answer

   • Define Indicated Power, mep, Brake Power
   • Define indicated thermal and mechanical efficiency
   • Relation between IP, BP and friction power
   • Formulas for each parameter
4. 7 Marks
   bThe initial condition of air in an Otto cycle is $288\text{ K}$ and $1.05\text{ bar}$. The air is compressed isentropically to pressure of $13\text{ bar}$. Then the heat is added at constant volume till the pressure becomes $35\text{ bar}$. Calculate

   1. i)Compression ratio
   2. ii)Air-standard efficiency
   3. iii)Mean effective pressure of the cycle
   How to answer

   • Use isentropic relation to get compression ratio from pressures
   • Calculate air-standard Otto efficiency $1-1/r^{\gamma-1}$
   • Find temperatures and heat added/rejected
   • Calculate mean effective pressure $W_{net}/V_s$
5. 7 Marks
   aWhat do you mean by normal and abnormal combustion? Discuss the detonation theories of S.I. engine. Enlist variables affecting detonation in S.I. engine.
   How to answer

   • Define normal vs abnormal combustion
   • Detonation theories in S.I. engine
   • Chemistry of auto-ignition and knock
   • Variables affecting detonation
6. 7 Marks
   bExplain the phenomenon of pre-ignition in S.I. engine. Does it cause knocking in the engines? Discuss the methods to control the knock. How the knock is rated?
   How to answer

   • Concept of pre-ignition and hot spots
   • Relation between pre-ignition and knocking
   • Methods to control knock
   • Rating of knock / octane number
7. 7 Marks
   aDefine flame speed and explain its importance in the design of S.I. engine combustion chamber. Draw neat layout of the following head combustion chambers (S.I. engines) and discuss their advantages and disadvantages.

   1. i)T-Head type
   2. ii)I-Head type
   3. iii)F-Head type
   How to answer

   • Definition of flame speed
   • Importance for combustion chamber design
   • Neat layouts of T-Head, I-Head, F-Head chambers
   • Advantages and disadvantages of each
8. 7 Marks
   bDiscuss the effects of the following parameters on the flame propagation.

   1. i)A : F ratio
   2. ii)Rc
   3. iii)RPM of engine
   4. iv)Engine load
   5. v)Turbulence
   How to answer

   • Effect of A:F ratio, compression ratio on flame speed
   • Effect of RPM, load and turbulence
   • Explanation of flame propagation mechanism
   • Optimum conditions for fast propagation
9. 7 Marks
   aExplain the phenomena of knocking diesel engines. What are the different factors which influence the knocking?
   How to answer

   • Mechanism of diesel knock vs S.I. knock
   • Stages of diesel combustion and delay period
   • Factors influencing knocking
   • Control measures
10. 7 Marks
    bA 6-cylinder, 4-stroke oil engine develops $200\text{ kW}$ at $1200\text{ RPM}$ and consumes $0.3\text{ kg/kWh}$. Determine the diameter of a single orifice injector if the injection pressure is $200\text{ bar}$ and combustion chamber pressure is $40\text{ bar}$. The injection is carried out for $30^\circ$ rotation of a crank. Take $\rho_f = 900\text{ kg/m}^3$ and $Cd_f = 0.7$. Each nozzle on a cylinder provided with single orifice.
    How to answer

    • Calculate fuel consumption per cylinder per cycle
    • Find injection duration from crank angle and RPM
    • Apply orifice flow formula with $Cd_f$ and $\Delta p$
    • Solve for orifice diameter
11. 7 Marks
    aExplain with a neat diagram the principle, construction and working of MPFI system.
    How to answer

    • Principle of MPFI system
    • Constructional components with neat diagram
    • Working sequence of multi-point injection
    • Advantages for performance and emission
12. 7 Marks
    bDefine carburetion. Describe with a neat diagram the working of a Solex carburetor. Explain different types of cooling systems of I.C. engine.
    How to answer

    • Definition of carburetion
    • Working of Solex carburetor with diagram
    • Circuits for starting, idling, main and power
    • Types of I.C. engine cooling systems
13. 7 Marks
    aWhat are the different kinds of fuels used in an IC engine? Draw a line diagram of petroleum refining process and briefly discuss the petroleum refining processes.
    How to answer

    • Kinds of IC engine fuels - solid, liquid, gaseous
    • Line diagram of petroleum refining process
    • Brief description of distillation, cracking, reforming
    • Fuel properties for S.I. and C.I. use
14. 7 Marks
    bGive the chemical formula for the following. State their molecular arrangement and mention whether they are saturated or unsaturated.

    1. i)Olefin
    2. ii)Paraffin
    3. iii)Naphthene
    4. iv)Aromatic
    How to answer

    • Chemical formula of olefin, paraffin, naphthene, aromatic
    • Molecular arrangement - chain, ring structures
    • Saturated vs unsaturated classification
    • Examples $C_nH_{2n+2}$, $C_nH_{2n}$, etc.
15. 7 Marks
    aWhat is meant by super charging? Discuss the different methods of supercharging used in practice. List out merits and demerits of each method.
    How to answer

    • Meaning of supercharging and need
    • Different methods - mechanical, turbo, etc.
    • Working of each method with merits
    • Demerits and applications of each
16. 7 Marks
    bExplain the purpose of cooling system used in IC engines. Explain only two of the following with neat sketch.

    1. i)Thermosyphon cooling system
    2. ii)Forced circulation cooling system
    3. iii)Evaporative cooling system
    How to answer

    • Purpose of cooling - prevent overheating, maintain efficiency
    • Sketch and working of any two cooling systems
    • Comparison of thermosyphon, forced, evaporative
    • Advantages and limitations