Abstract:
The study aims to experimentally characterize the nano-particle emissions and un-regulated (i.e., saturated and unsaturated
hydrocarbons and formaldehyde emissions) emissions. Present study experimentally investigates the effect of
high reactivity fuel injection timings and port-injected-fuel mass on nano-particle and unregulated emissions in the
gasoline-diesel RCCI engine. Additionally, empirical correlations are developed using experimental data for the estimation
of particle emission characteristics. An automotive single cylinder diesel engine is modified for an in-cylinder
blending of port-injection of gasoline during suction stroke and direct-injection of diesel fuel during the compression
stroke. The experiments are performed on a modified engine for various diesel injection timings and port-injected
gasoline mass using development electronic control unit (ECU). Nano-particle and unregulated emissions are measured
using electrical mobility based particle-sizer and Fourier-transform infrared spectroscopy analyser respectively.
Combustion analysis is performed by in-cylinder pressure measurement. The experimental data of nano-particle and
combustion characteristics are used for the development of empirical correlation using a multivariable regression
technique for determining the particle number characteristics. The parameters - premixing ratio, start of injection of
diesel, and a novel parameter defined as premixed fraction of total heat release are used for the development of
empirical correlations and found a good correlation for estimating the nano-particle emission characteristics. Results
also indicate that advanced direct injection timing and increase in the port-injected gasoline mass leads to higher
particle emissions as well as saturated, unsaturated hydrocarbon and formaldehyde emissions.
