Investigation of evaporation and engine characteristics of pine oil biofuel fumigated in the inlet manifold of a diesel engine

•Pine oil biofuel is operated in diesel engine through fumigation in inlet manifold.•Evaporation of pine oil droplet vaporization are captured and coupled with engine study for the first time.•Evaporation characteristics of pine oil were better at higher temperature of 150°C.•BSFC was 16.2% lower for 36% pine oil injection than 6% pine oil injection at 100% load.•Peak heat release rate and maximum in-cylinder pressure increased with the increase of pine oil injection at 100% load. Pine oil biofuel, obtained by the distillation of oleoresins of pine tree, has been chosen as a new renewable fuel for its operation in diesel engine. Notably, the viscosity and cetane number of pine oil was observed to be lower than diesel. The motivation for this work stems from the basic notion that less viscous and lower cetane fuels are considered to be fumigated for their successful operation in diesel engine. As such, pine oil biofuel was vaporized and inducted into the engine cylinder through inlet manifold while diesel was sent through main injection system, providing ignition assistance for the pine oil/air mixture. Prior to conducting engine experiments, the evaporation characteristics of pine oil droplet were studied through suspended droplet experiment so as to get better insights on pine oil droplet evaporation at various temperatures. From this study, it was observed that at higher air temperature (150°C), evaporation of pine oil was more effective than at lower temperatures (100°C and 50°C) and therefore, 150°C was chosen as preheat temperature for engine fumigation study. Thus, as a novel attempt, the fundamental study on pine oil droplet evaporation is subtly coupled with engine studies, and the effect of vaporization of pine oil on engine characteristics was mapped. As an outcome of engine study, the maximum percentage of diesel replaced was noticed to be 36% at 100% load and 60% at 20% load. Significantly, the engine performance such as BSFC and BTE was observed to be improved with the increase in proportion of pine oil injection. Further, combustion of fumigated pine oil has been reported to be better, with 36% injection of pine oil showing 10.3% higher in-cylinder pressure than that for 6% injection of pine oil at 100% load.