___________________ ______________ MIT OpenCourseWare http://ocw.mit.edu 2.61 Internal Combustion Engines Spring 2008 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.Hydrocarbon Pathway - Steady State, cruise condition Fuel (100%) HC MechanismsFlame converts fuel to CO2, CO, H2O, H2 etc. Liq. Fuel 1.2% Deposits (1%) Oil Layers (1%) Quenching (0.5%) Crevices (5.2%) Exh. Valve Leakage (0.1%) ---------------- Fuel Only ---------------- --------------- Fuel- Air Mixture ---------------Blow-by (0.6%) - Recycled -1/3 Oxidized 2/3 Oxidized Unburned HC in Residual (1.3%) - Recycled -Fully Burned Exhaust Engine- out HC (1.6%) Tailpipe- out HC (0.1-0.4%) In-Cylinder Oxidation 91% 9% Exhaust Oxidation (0.8%) 2.5% 4.6% 5.1% 1.7% 1.7% 3.4% 1/32.3% 1/3 Catalyst 1.5% Crankcase (0.7%) - Recycled -HC Sources: Magnitudes and Percent of Total Engine-out Emissions Source % Fuel Escaping Fraction Emitted % Fuel as HC % of Total EOHC Normal Combustion as EOHC Emissions Emissions Crevices 5.2 0.15* 0.682* 42.6 Quench 0.5 0.15 0.074 4.6 Oil Layers 1.0 0.09** 0.090** 5.6 Deposits 1.0 0.30 0.300 18.7 Liquid Fuel 1.2 0.30 0.356 22.2 Valve Leakage 0.1 1.00 0.100 6.3 Total 9.0 1.60 100 * Blowby (0.6%) subtracted ** Amount to crank case (0.7%)
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