Piston bowl shape and biodiesel fuel effects on combustion and emission of diesel engines

Abstract

Abstract This study aims to investigate the effects of piston bowl shape and biodiesel fuel on combustion and emissions of a direct injection (DI) diesel engine. Three configurations of piston bowl geometry are modeled: hemispherical, toroidal, and rectangular. Biodiesel fuel derived from soybean oil is being considered. An experimental work was conducted on a diesel engine with a hemispherical piston bowl, and a better validity was attained. The study showed that, diesel engine with toroidal piston bowl delivered the largest power than other shapes, where turbulent regions are formed inside the toroidal piston bowl with higher intensity, which resulted in better combustion characteristics and lower emission concentrations. It is observed from the combustion of biodiesel fuel that, the rapid combustion stage began earlier than conventional diesel fuel by about 5o CA, heat release rate (HRR) decreased by 18.88%, emissions of carbon monoxide (CO), and unburnt hydrocarbon (UHC) reduced but nitric oxide (NO) emission increased by about 17.78% at 55o CA, as compared to diesel fuel. During the injection process, the jet core of biodiesel fuel appeared thicker and longer than conventional diesel fuel. For optimization, preheating with exhaust gas recirculation (EGR) of biodiesel fuel contributes to reduce the emissions of nitrogen oxides (NOx) and improve the atomization rate.

Keywords

• Piston bowl shape
• Biodiesel
• Diesel engine
• Combustion
• Emission