Sascha Nicklitzsch

Selecting a suitable stroke / bore ratio when combining variable compression and Early Intake Valve Closure (EIVC)

Increasingly strict fuel consumption and emission legislation is forcing engine developers to use combinations of technologies that complement each other to produce high potential for cutting fuel combustion.

NO Laser-Induced Fluorescence Imaging in the Combustion Chamber of a Spray-Guided Direct-Injection Gasoline Engine

In direct-injection gasoline (GDI) engines with charge stratification, minimizing engine-out nitrogen oxide (NO x ) emission is crucial since exh ust-gas aftertreatment tolerates only limited amounts of NO x . Reduced NO x production directly lowers the frequency of energy-inefficient catalyst regeneration cycles. In this paper we investigate NO formation in a realistic GDI engine. Quantitative in-cylinder measurements of NO concentrations are carried out via laser-induced fluorescence imaging with excitation of NO (A-X(0,2) band at 248 nm), and subsequent fluorescence detection at 220-240 nm. Engine modifications were kept to a minimum in order to provide results that are representative of practical operating conditions. Optical access via a sapphire ring enabled identical engine geometry as a production line engine. The engine is operated with commercial gasoline (Super-Plus, RON 98). Recent high-pressure spectroscopic studies of NO, O 2 and CO 2 are utilized to select an appropriate detection scheme for quantitative NO measurements under realistic conditions. CO 2 UV light absorption data is used to correct for laser and signal attenuation. NO-LIF concentrations are compared to extractive measurements using a fast gas sampling valve (GSV). NO formation is investigated at different operating conditions such as variable exhaust gas recirculation (egr).