Stoichiometric Compression Ignition (SCI) Engine

Experimental investigations were conducted on a novel, Stoichiometric Compression Ignition (SCI) combustion system designed to operate a diesel engine at stoichiometric equivalence ratios. Development of such a combustion concept offers the potential to retain the advantages of the diesel cycle while combining simple, reliable three-way catalyst technology for NOx control. Traditionally, operation of a diesel engine at near stoichiometric equivalence ratios has resulted in excessive particulate matter (PM) emissions due to the heterogeneous, stratified nature of diesel combustion in conjunction with reduced A/F ratios. However, development of the SCI combustion concept has displayed the potential to reduce PM emissions at stoichiometric equivalence ratios to levels manageable by a diesel particulate filter (DPF). Nitrogen Oxides (NO_x) emissions would meet Final Tier 4 standards, assuming conservative three-way catalyst conversion efficiencies are obtainable. Preliminary results indicate the potential to efficiently meet upcoming emissions standards without the use of complicated NO_x aftertreatment systems such as Selective Catalytic Reduction (SCR) or Lean NOx Trap (LNT).