The combined effect of low viscous biofuel and EGR on NO-smoke tradeoff in a biodiesel engine—an experimental study

The present study aims to study the effect of low viscous biofuel, namely pine oil (PO) and orange oil (O) blending with Jatropha methyl ester (JOME) along with exhaust gas recirculation (EGR) on NO-smoke tradeoff in a single-compression ignition (CI) engine. Two blends of pine oil and orange oil (30% by volume) with JOME were prepared and tested at 10%, 15%, and 20% EGR rates for various load conditions and compared with base fuels. JOME operation increased NO emission by 4% and reduced smoke opacity by 10% in comparison to diesel at maximum load condition. Poor physical properties of JOME, namely high viscosity and inferior volatility leads to reduced brake thermal efficiency with higher HC and CO emissions. Blends of JOME with low viscous biofuel reduces smoke emission with a further increase in NO emission in comparison to JOME as a result of combustion enhancement. Addition of EGR with JOME70 + PO30 and JOME70 + O30 aids in the reduction of NO emission with a slight increase in smoke opacity. Considering the NO-smoke tradeoff, JOME70 + O30 + EGR (10%) is optimum, NO emission is reduced by 14% and 11% in comparison to JOME and diesel and smoke opacity is reduced by 5% and 15% in comparison to JOME and diesel at maximum load, respectively.