The Influence of Charge Dilution and Injection Timing on Low-Temperature Diesel Combustion and Emissions

摘要: The effects of charge dilution on low-temperature diesel combustion and emissions were investigated in a small-bore single-cylinder engine over wide range injection timing. fresh air was diluted with additional N 2 CO , simulating 0 to 65% exhaust gas recirculation an engine. Diluting the intake lowers flame temperature T due reactant being replaced by inert gases increased heat capacity. In addition, is anticipated influence local equivalence ratio Φ prior ignition lower O concentration longer delay periods. By influencing both T, impacts path representing progress process Φ-T plane, offers potential avoiding soot NO x formation. In-cylinder pressure measurements, exhaust-gas emissions, imaging luminosity performed clarify timing fuel conversion efficiency. Based findings, postulated plane presented for different levels timings. Although high early injection, release analysis indicated that large portion formation processes still dominated mixing-controlled phase rather than premixed phase. Because incomplete premixing, need mix greater volume unbumed or partially-burned complete combustion, mixtures emissions. Injecting at earlier timings extend helped alleviate this problem, but did not eliminate it. Fuel efficiencies calculated each level start provide guidance as appropriate phasing practical regime.