Glycerine emulsions of diesel-biodiesel blends and their performance and emissions in a diesel engine

The extensive use of biodiesel as an alternate fuel has resulted in the oversupply of glycerine, leading to an increased demand to look for the use of glycerine as an alternate fuel. In this paper, multiple blends of diesel-biodiesel and their glycerine emulsions were compared to investigate the performance and emissions in a modern small diesel engine. A direct injection diesel engine was tested at different loads and speed conditions. Biodiesel was produced onsite and crude glycerine obtained as a by-product was purified using an orthogonal test method. Hydrophilic-lipophilic balance was formulated using two surfactants: Polyoxyethylene Sorbitan Monooleate and Sorbitan Monooleate, which were used in the emulsification process to attain desired stability of glycerin emulsion. Emulsion stability, mean particle droplet size, fuel properties, engine performance, and emissions were examined. Test results show that with the increase in glycerine concentration, brake-specific fuel consumption and brake-thermal efficiency increased. In terms of emissions, it was seen that carbon monoxide and unburned hydrocarbon increased, and reductions in exhaust gas temperature and oxides of nitrogen were observed. In addition, there was a significant decrease in smoke (approximately 80%) with an increased concentration of glycerine at 3000 rpm, at high load.