Effect of EGR on combustion and exhaust emissions in supercharged dual-fuel natural gas engine ignited with diesel fuel

Eiji Tomita, Yuji Harada, Nobuyuki Kawahara, Atsushi Sakane

Research output: Contribution to journalConference article

18 Citations (Scopus)


The combustion and exhaust emissions characteristics of a supercharged dual-fuel natural gas engine with a single cylinder were analyzed. We focused on EGR (Exhaust Gas Recirculation) to achieve higher thermal efficiency and lower exhaust emissions. The combustion of diesel fuel (gas oil) as ignition sources was visualized using a high-speed video camera from the bottom of a quartz piston. The luminous intensity and flame decreased as the EGR rate increased. Furthermore, the ignition delay became longer due to the EGR. Characteristics of the combustion and exhaust emissions were investigated with changing EGR rates under supercharged conditions. The indicated mean effective pressure and thermal efficiency decreased with increasing EGR rate. In addition, NOx emissions decreased due to the EGR. In this study two-stage combustion was observed. When two-stage combustion occurred, it was supposed that auto-ignition of compressed natural gas and air mixture occurred during the flame development. However, knocking did not occur. Two-stage combustion occurred under the condition of low EGR rate and advanced injection timing. The indicated mean effective pressure and thermal efficiency increased, during two-stage combustion; however, NOx emissions also increased by a large amount compared to normal combustion. High indicated mean effective pressure, high thermal efficiency, and low NOx emissions were achieved just before the occurrence of two-stage combustion by changing EGR rate and injection timing of diesel fuel.

Original languageEnglish
JournalSAE Technical Papers
Publication statusPublished - Jan 1 2009
EventPowertrains, Fuels and Lubricants Meeting, SFL 2009 - Florence, Italy
Duration: Jun 15 2009Jun 15 2009


ASJC Scopus subject areas

  • Automotive Engineering
  • Safety, Risk, Reliability and Quality
  • Pollution
  • Industrial and Manufacturing Engineering

Cite this