A complete assessment on the impact of in-cylinder and external blending of eucalyptus oil on engine's behavior of a biofuel-based dual fuel engine.

This work aims at combusting a high viscous high cetane biofuel completely and efficiently under dual combustion mode using another low viscous low cetane biofuel. Maduca longifolia oil (MO) was selected as the base fuel. Combustion was achieved by using EFI (electronic fuel injection) and carburetion of eucalyptus oil at the intake manifold. Eucalyptus oil was also blended externally with MO at different mass ratios and tested. A comparison of engine results was made at 100% and 40% loads (power outputs) for all the attempts. Test results indicated significant improvement in BTE (brake thermal efficiency) with all modes with moderate energy shares of eucalyptus oil. The BTE increased from 25.2% with neat MO operation to a maximum of 29%, 32.3%, and 33.4% respectively with eucalyptus oil addition, carburetion, and EFI modes whereas it was observed as 30.8% with ND (neat diesel). Smoke was reduced with eucalyptus oil addition, carburetion, and EFI at the maximum efficiency points at 100% load. Peak pressure and energy-release rate indicated as superior to neat MO at all modes mainly at 100% load. Thirty percent, 40.2%, and 30.4% respectively with eucalyptus oil addition, carburetion, and EFI were recommended to be the optimal mass shares for 100% load. EFI of eucalyptus oil could be preferred for the highest BTE, lowest smoke, and NO emissions and maximum replacement of MO for the optimal operation of the engine among the methods tested.