Combustion and emissions of gasoline, anhydrous ethanol, and wet ethanol in an optical engine with a turbulent jet ignition system

Abstract

Turbulent jet ignition is a pre-chamber ignition system for an otherwise standard gasoline spark ignition engine. Turbulent jet ignition works by injecting chemical active turbulent jets to initiate combustion in a premixed fuel/air mixture. The main advantage of turbulent jet ignition is its ability to ignite and burn completely very lean fuel/air mixtures in the main chamber charge. This occurs with a very fast burn rate due to the widely distributed ignition sites that consume the main charge rapidly. Rapid combustion of lean mixtures leads to lower exhaust emissions due to more complete combustion at lower combustion temperature. The purpose of the paper is to study the combustion characteristics of gasoline, ethanol, and wet ethanol when operated with the pre-chamber combustion system and the ability of the pre-chamber ignition to extend the lean-burn limits of such fuels. The combustion and heat release process was analyzed and exhaust emissions measured. Results show that the effect of turbulent jet ignition system on the lean-burn limit and exhaust emissions varied with fuels. The lean limit was extended by using fueled pre-chamber furthest, to λ = 1.71 with gasoline, followed by λ = 1.77 with wet ethanol and λ = 1.9 with ethanol. NOx emissions were significantly reduced with increased lambda for each fuel under stable combustion conditions. For ethanol, at maximum lean limit lambda 1.9, the NOx emissions were almost negligible due to lower combustion temperature.

Development and validation of a novel quasi-dimensional combustion model for un-scavenged prechamber gas engines with numerical simulations and engine experiments

“…Experiments to characterise the effect of prechamber design parameters variations on the engine performance or emissions have been extensively investigated. 12–14 The prechamber nozzle area and volume drastically determine combustion stability, efficiency, UHC and NOx emissions by influencing the early phase of main chamber combustion through the jet momentum and jet-induced turbulence. 4,15–18 Sweeps of the engine’s operating parameters, and in particular of the prechamber air-to-fuel ratio, present fundamental interest due to the potential of extending the lean misfire limit of the engine.…”

The use of active jet ignition to overcome traditional challenges of pre-chamber combustors under low load conditions

“…Pre-chamber combustion concepts have demonstrated the potential for stable main chamber combustion at higher levels of dilution than are allowable in typical SI engines. 11,12 They have also demonstrated the ability to counter the loss of ignitability of the lean charge. This capability results in an extension of the lean limit of the engine.…”

Analysis of a stratified pre-chamber spark ignition system under lean mixture conditions

“…The biggest challenge for the PCSI system is to reduce NOx, CO and HC emissions simultaneously [85,86]. Ultra lean combustion ensures a low combustion temperature that inhibits formation.…”