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Explore the impact of valve design and operational factors on engine volumetric efficiency, from selection of valve timing to thermodynamic parameters and fuel composition. Discover ways to improve filling and emptying effectiveness for optimal engine performance.
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Influence of (Valve) Design & Operational Parameters on Volumetric Efficiency of Engine P M V Subbarao Professor Mechanical Engineering Department Clues to Improve Filling & Emptying Effectiveness….
Frictional Compressible Flow Through Inlet Valve • The real gas flow effects are included by means of an experimentally determined discharge coefficient CD. When the flow is chocked:
Discharge Coefficient: The value of CD and the available minimum flow area Amin are linked together. The product CD . Amin is the effective flow area of the valve assembly, AE.
Non-dimensional available flow area for real Flow through INLET VALVES a b c
Thermodynamic Parameters Vs Volumetric Efficiency • The volumetric efficiency is a function of • Intake mixture pressure pi. • Intake mixture Temperature Ti. • Fuel/ air ratio (F/A). • Compression ratio r. • Exhaust pressure, pe. Where m is the mass of mixture in the cylinder at the end of intake stroke.
Effect of Fuel composition, Phase & Fuel/air Ratio • In a SI engine, the presence of gaseous fuel and moisture in the intake system reduces the air partial pressure below the mixture pressure. • For a mixture:
Fuel Chemistry Vs Volumetric Efficiency 1.0 C8H18 Pa,I/pi CH4 H2 0.6 1.5 Equivalence Ratio 0