OIL AEROSOL EMISSION OPTIMISAITON IN HIGH POWER DIESEL ENGINE USING DEFLECTORS IN TURBO CHARGER OIL DRAIN CIRCUIT

Closed crankcase ventilation prevent harmful gases from entering atmosphere thereby reducing hydrocarbon emissions. Ventilation system carries blowby gases leaking through combustion process along with oil mist to Engine intake system. Major sources of blowby often occurs from leak in combustion chamber through piston rings, leaks from turbo shafts & valve guides. Oil mist carried away by blowby gases gets separated using filtration media. Fleece type separation media has high separation efficiency for particles above 10 microns. Efficiency drops if mist particle is below 10-micron size. Low size aerosol mist generally forms due to flash boiling on piston under crown area and on shafts of turbo charger due to high speeds combined with elevated oil temperatures. High power density diesel engine is taken for our study. It produces low particle size oil mist which contributes to aerosol emission of 3 gm/hr when operated at rated speed. Particle size measurement done using light refraction technique. To understand formation of low particle size oil mist, Turbo charger lubrication is disconnected from Engine during measurement. 30 % improvement in aerosol emission observed without turbo charger lubrication. Blowby carries oil mist though crankcase passage if the mist particles produced from turbocharger are lighter & smaller. Deflectors are designed in turbo charger oil drain circuit which converts lighter & smaller droplets to heavier droplets which cannot get carried away with blowby gases. Oil aerosol emission improvement of 30 % observed with introduction of deflectors in turbo charger oil drain circuit. Improvement can be seen across all Engine speed load conditions. Oil aerosol emission optimized without making any change in mist separation system