Influence of plasma-assisted ignition on flame propagation and performance in a spark-ignition engine

Lean-burn is an attractive concept for reasons of high thermal efficiency and low nitrogen oxide (NOx) emissions, however, successful implementation in spark-ignition (SI) engines turned out to be challenging because misfire or partial burn caused by attenuated flame propagation. In order overcome this issue, microwave-assisted plasma ignition system (MAPIS) has been applied combustion systems. The MAPIS consists a conventional coil, non-resistor spark plug, mixing unit, waveguide, magnetron (2.45GHz, 3kW). A series experiments was carried understand discharge characteristics validate its performance constant volume vessel as well single-cylinder engine. fundamental investigation based on optical emission spectroscopy imaging showed that the ejection microwave beneficial produce more reactive species such OH O radicals thanks higher electron temperature than ignition. lean limit able extended up equivalence ratio 0.5 larger initial kernel size with test. Meanwhile, engine test, stability noticeably improved showing smaller cycle-to-cycle fluctuations in-cylinder pressure. Improvement fuel 6% could achieved stable operation under fuel-lean conditions. terms advantageous reduce carbon monoxide (CO) emissions promoting complete combustion.