Comparative investigation of the effect of hemispherical and toroidal piston bowl geometries on diesel engine combustion characteristics

Diesel engine parameters are in general more compatible with operating on neat diesel than biodiesel and its blends. Therefore, optimizing operating conditions as well as piston bowl geometry to achieve a better performance with biodiesel in conventional diesel engines is highly essential. In the present study, hemispherical piston bowl geometry (HPBG) of existing diesel engine was modified into toroidal piston bowl geometry (TPBG) to evaluate the performance of a diesel engine running on a 20% blend of dairy scum oil biodiesel (B20). The experimental results revealed increased brake thermal efficiency and heat release rate by 5.5% and 17.24%, respectively, while brake specific fuel consumption, HC emission, and CO emission were decreased by 8.75%, 15%, and 14.47%, respectively, in response to the engine modification applied. Such improvements using the TPBG could be attributed to improved fuel atomization, reduction of fuel droplet size, increased cylinder temperature, enhanced squish-swirl, and turbulence kinetic energy during combustion. The findings of the present study could pave the way for the fabrication of diesel engines, which are more efficiently compatible with biodiesel and its blends

Microscopic characteristics of biodiesel – Graphene oxide nanoparticle blends and their Utilisation in a compression ignition engine

Use of nano-additives in biofuels is an important research and development topic for achieving optimum engine performance with reduced emissions. In this study, rice bran oil was converted into biodiesel and graphene oxide (GO) nanoparticles were infused into biodiesel-diesel blends. Two blends containing (i) 5% biodiesel, 95% diesel and 30 ppm GO (B5D95GO30) and (ii) 15% biodiesel, 85% diesel and 30 ppm GO (B15D85GO30) were prepared. The fuel properties like heating value, kinematic viscosity, cetane number, etc. of the nanoadditives–biodiesel-diesel blends (NBDB) were measured. Effects of injection timing (IT) on the performance, combustion and emission characteristics were studied. It was observed that both B15D85GO30 and B5D95GO30 blends at IT23° gave up to 13.5% reduction in specific fuel consumption. Compared to diesel, the brake thermal efficiency was increased by 7.62% for B15D85GO30 at IT23° and IT25°. An increase in IT from 23° to 25° deteriorated the indicated thermal efficiency by 6.68% for B15D85GO30. At maximum load condition, the peak heat release rates of NBDB were found to be lower than the pure diesel at both IT. The CO, CO2 & NOx emissions were reduced by 2–8%. The study concluded that B15D85GO30 at IT23° gave optimum results in terms of performance, combustion and emission characteristics