Emission and Deposit Formation in Direct Injection Stratified Charge SI Engines

摘要: A promising approach to increase the efficiency of spark ignition (SI) engine is inject fuel directly into cylinder form a stratified charge. There potential reduce consumption at low speeds and loads by 20 - 25% compared with conventional SI engines stoichiometric homogeneous The main drawbacks contemporary direct injection charge (DISC) are high hydrocarbon (HC) soot emissions. An experimental investigation sources HC emissions, from production Mitsubishi GDI ® which uses wall-guided mixture preparation, presented in this thesis. engine-out emissions were 50% higher for operation than tested under load speed conditions investigated. comparison cycle-resolved NOx was made operation. Distinct differences observed concentration traces indicate clearly that not same as engines. measurements over mixing (quenching), boundaries air/fuel cloud, mixing, both spray center on surface piston bowl, dominating mechanisms emission formation engine. more sensitive composition While there only marginal DISC altering distillation curve fuel, much greater decrease improving combustion systems. Injector fouling found have detrimental effect stability when subjected 60 h deposit accumulation cycle. frequency misfires and/or partial burns became unacceptable after such short time intervals 6 30 some gasolines tested. Although levels depend composition, it concluded study chamber deposits did due primarily reduced heat transfer. It clear these tests preventing injector essential