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 (NOx) 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 NOx aftertreatment systems such as Selective Catalytic Reduction (SCR) or Lean NOx Trap (LNT).
