The attainment of premixed compression ignition low-temperature combustion in a compression ignition direct injection engine

This study theoretically proposes and experimentally demonstrates the simultaneous reductions of exhaust nitric oxide (NO) and soot via the attainment of premixed compression ignition (PCI) combustion in a modern compression ignition direct injection (CIDI) engine. The key features leading to PCI combustion are a well-mixed fuel-air mixture, following a long ignition delay period, which burns at relatively low temperature. It is shown that simultaneous reductions in exhaust NO and soot concentrations are possible with the implementation of PC] combustion. At very low combustion temperatures, soot formation mechanisms decrease substantially so that both NO and soot formation have very little dependence on local equivalence ratios. As a result, it becomes possible to increase the global equivalence ratio above stoichiometric, and produce rich products of combustion for regeneration of certain diesel aftertreatment systems. (C) 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.