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Discover the engineering principles behind combustion in SI & IC engines. Learn about ignition energy, spark plugs, fuel types, and optimization strategies for efficient engine performance.
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Combustion of Homogeneous Mixtures in S.I. I.C. Engines P M V Subbarao Professor Mechanical Engineering Department A Baby Care Engineering for A Quick & Comprehensive Phenomenon…...
Engineering of Ignition Temperature 25 C 0
Type of Fuel Vs Traditional Combustion Strategy • Highly volatile with High self Ignition Temperature: Spark Ignition. • Ignition after thorough mixing of air and fuel. • Less Volatile with low self Ignition Temperature: Compression Ignition , Almost simultaneous mixing & Ignition.
Spark Ignition System Edmond Berger invented an early spark plug on February 2, 1839.
Paschen Curve : 1889 Paschen found that breakdown voltage was described by the equation Where V is the breakdown voltage, p is the pressure, d is the gap distance. The constants a and b depend upon the composition of the gas. For air at standard atmospheric pressure of 101 kPa, a = 43.6×106 V/(atm·m) and b = 12.8. What is supplied by an Ignition System ?
Theoretical & Practical Minimum Spark Energy • The minimum ignition energy is a measure of required energy for a localised ignition source to successfully ignite a fuel-air mixture. • The ignition energy depends on the fuel concentration. • For most combustible fuels the minimum ignition energy is between 0.1 and 0.3 mJ in normal ambient air. • The practical minimum energy required to ignite a air-fuel mixture is much higher. • Effect of Various Parameters on MIE: • Distance Between Electrodes • Fuel • Equivalence Ratio • Initial Temperature • Air Movement
Ignition energy in air at 1 atm, 20C Fuel E’ (10-5J) Methane 33 Ethane 42 Propane 40 n-Hexane 95 Iso-Octane 29 Acetylene 3 Hydrogen 2 Methanol 21
Fluid Dynamics & Thermo Chemistry of Ignition Energy Supplied by Coil, ES, mJ
Combined Thermodynamic & Chemical Optimization for Better Reaction in SI Engines r = 8 r = 10
Effect of Equivalence Ration on Laminar Burning Velocity Methanol Propane Sflamelet,p Gasoline Isooctane Methane
Combined Thermodynamic & Kinetic Optimization for Better Reaction in Si Engines
Development of Combustion Science for Eco-friendly SI Engines