Emission profiling of CI engine fueled with neem and wintergreen oil blend with hexanol and octanol manifold injection

The present work details the effects of injection of higher order alcohols, namely hexanol (Hex) and octanol (Oct) as secondary fuels in a CI engine. The last decade has seen an exponential increase in the carbon emission chief of which have been contributed by fossil fuels. Vegetable oils provide a viable alternative to the current scenario as they can be synthesized easily from nature and can be readily adapted for use in CI engines. Neem oil (NO) is non-edible and widely available and hence taken as a base fuel for this research. The poor properties of neem oil were improved by the addition of novel low viscous biofuel, namely wintergreen oil (WGO). During the course of this research work, a blend containing a mixture of 50% of neat neem oil and 50% of wintergreen oil (NO50-WGO50) was optimized based on trial tests and taken as pilot fuel while Hex and Oct were injected along with intake air as secondary fuels. The alcohols were injected into the engine successively in the 10%, 20%, and 30% (by mass) ratios. Experiments were conducted in a single-cylinder CI engine fabricating 5.2-kW power at a constant speed of 1500 rpm at varying load conditions. It is observed that inferior performance of NO led to more smoke, HC, and CO in comparison to diesel at all the loads and these are improved with NO50-WGO50 blend. Nevertheless, a minor increase in NOx emission was perceived with the blend. Addition of higher order alcohol promoted reduction of both NOx and smoke emission without affecting performance. Among the various combinations, NO50-WGO50 + Hex30 and Oct30 reduced NOx emission by 12% and 9.5% and smoke emission by 13% and 19% respectively. These results are on par with the diesel performance and emission characteristics.