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A Gasoline Fueled Pre-Chamber Jet Ignition Combustion System at Unthrottled Conditions
Abstract:
Turbulent Jet Ignition is an advanced spark-initiated
pre-chamber combustion system for otherwise standard spark ignition
engines. Combustion in the main chamber is initiated by jets of
partially combusted (reacting) pre-chamber products which provide a
high energy ignition source. The resultant widely distributed
ignition sites allow relatively small flame travel distances
enabling short combustion durations and high burn rates.
Demonstrated benefits include ultra-lean operation (λ≻2) at part
load and high-load knock improvement near stoichiometric
conditions.
Although previous results of this combustion system have been
very promising, the main hurdle of this system has been the need
for a dual-fuel system, with liquid gasoline used in the main
combustion chamber and small fractions of gaseous propane in the
pre-chamber. The purpose of this paper is to demonstrate that this
combustion system can operate robustly using a sole gasoline
system, with vaporized gasoline found to be a successful substitute
for the pre-chamber propane over all comparable conditions. With
this concept, the test engine recorded a peak net thermal
efficiency of 42.8% (190 g/kWh ISFCn) and single-digit engine-out
NOx emissions. The pre-chamber jet ignition system was also
examined at unthrottled stoichiometric conditions up to 5500
rev/min, with successful operation demonstrated up to 13.2 bar
IMEPn. Additionally, jet ignition combustion was also examined in
order to evaluate pressure rise rate limitations for potential
future high-load powertrain applications.