Diesel Stoichiometric Combustion

1. Diesel Stoichiometric Combustion Spray Included Angle SANGSUK LEE & Rolf D. REITZ Motivation Operating Conditions Effects of Op. Parameters on Fuel Consumption under stoichiometric Operation • Diesel engines face difficulties in satisfying emission regulations, especially reducing NOx emissions. • Three-way catalyst is an well-established technology with gasoline engines. • Can the three-way catalyst be used with diesel engines? • Fuel Economy is top priority! • Emissions Linear Regression* (R2 = 80%) Injector Nozzles ISFC (g/kW-hr) = 307 – 0.38xBoost P. – 0.21x Inj. P. + 5.82xSwirl – 0.11xSOI + 0.11xFuel Mass– 0.06xIntake Temp. • 130° (8-hole) • 400 cm3 / 30 min • under 100bar Boost Pressure ~ Injection Pressure > Swirl > Fuel Mass ~ SOI ~ Intake Temp. ~  Objectives • To explore characteristics of rich diesel combustion • To achieve Diesel Stoichiometric Combustion with acceptable fuel economy impact • To identify achievable level of fuel consumption under stoichiometric operation with current strategies • To evaluate the effects of operating parameters on diesel stoichiometric characteristics • Combustion regimes don’t have significant effect on fuel consumption as  becomes richer. • 7% fuel consumption disadvantage at  = 1.0 * Minitab Combustion Phasing on Fuel Consumption Split Injection under phi = 1.0 Emissions under phi = 1.0 Conclusions ISFC • Fuel consumption and emissions characteristics are determined mostly by the equivalence ratio under rich diesel combustion. • PCCI combustion showed a low level (0.2 g/kW-hr) of soot emission even at stoichiometric operation. • Stoichiometric operation yielded ISFC levels of about 245 g/kW-hr which is around 7% higher than that of the best fuel economy case under leaner standard diesel operation. • High boost pressure and injection pressure improved fuel consumption under stoichiometric operation while high swirl ratio sacrificed fuel consumption. • Phasing of the heat release rate had only a minor influence on the fuel consumption since better phasing was accompanied by longer burn durations which canceled the gain. • PCCI based split injections under stoichiometric operation did not have significant fuel economy advantage while split injections with late injection impacted fuel economy due to improper air entrainment of 2nd spray. SOI = -35 & 15’ ATDC SOI = -35 & -15’ ATDC • Same Levels of ISFC and Heat rejection efficiency • Shifted combustion phasing doesn’t improve work conversion efficiency and fuel consumption. % Fuel Energy Wasted with CO and HC Emissions Red : Significant Effect > 2  Blue : Moderate Effect >  Black : negligible Effect <  4.7%