Effects of spray impingement, injection parameters, and EGR on the combustion and emission characteristics of a PCCI diesel engine

Robert Kiplimo, Eiji Tomita, Nobuyuki Kawahara, Sumito Yokobe

Research output: Contribution to journalArticle

158 Citations (Scopus)

Abstract

The effects of spray impingement, injection parameters, and exhaust gas recirculation (EGR) on the combustion characteristics and exhaust emissions of a premixed charge compression ignition (PCCI) diesel engine were investigated using a single-cylinder test engine and an optically accessible engine. Tests were carried out under constant speed with variable injection pressures and EGR rates. Exhaust emissions and in-cylinder pressures were measured under all experimental conditions. Analyses were conducted based on diesel spray evolution and combustion process visualisation coupled with performance and exhaust emissions. Higher injection pressures led to lower smoke, hydrocarbons (HC), and nitrogen oxide (NO x) emissions but had roughly the same CO emissions compared with lower injection pressures. Higher EGR rates led to the simultaneous reduction in NO x and soot emissions due to lower combustion temperatures compared to conventional diesel combustion. However, HC and CO emissions increased due to fuel impingement, bulk quenching, and over-mixing, leading to an air-fuel mixture that was too lean to burn. An optimum spray targeting spot was identified, leading to lower emissions of soot, CO, and HC but higher NO x emissions without EGR. The simultaneous reduction in NO x and soot was achieved using the optimum spray targeting spot by introducing EGR, which was accompanied by homogenous combustion and a low luminosity flame attributed to fuel impingement on the piston bowl wall.

Original languageEnglish
Pages (from-to)165-175
Number of pages11
JournalApplied Thermal Engineering
Volume37
DOIs
Publication statusPublished - May 1 2012

Keywords

  • Air-fuel mixture
  • Exhaust emissions
  • Flame luminosity
  • Internal combustion engine
  • PCCI
  • Spray

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

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