Experimental study on macro spray, combustion and emission characteristics of biodiesel and diethyl carbonate blends

Biodiesel has a higher viscosity and poorer atomization effect compared to traditional diesel fuel, resulting in lower combustion efficiency. This study investigated the effects of exhaust gas recirculation and a diethyl carbonate additive on the combustion and emission of biodiesel blends. Biodiesel was blended with DEC (90% volume biodiesel + 10% volume DEC: B90DEC10). Experiments were conducted at various brake mean effective pressures (BMEP: 0.2, 0.6, 1.0, 1.6, and 2.0 MPa) and EGR rates (0, 5, and 15%) on a direct injection and high pressure common rail diesel engine that met Euro VI emission standards. The results revealed that the viscosity and atomization effects of B90DEC10 were improved, and the premixed combustion period was longer and the heat release rate (HRR) was higher compared to traditional diesel. The maximum HRR of B90DEC10 was 20% higher than that of diesel at 0.6 MPa. Compared to diesel, the particulate matter emissions of B90DEC10 were reduced by 92%, and total hydrocarbons and carbon monoxide emissions were significantly reduced. However, there was an increase of 8–20% in nitrogen oxide emissions. At an EGR rate of 15%, the NO_x emissions of B90DEC10 were reduced by 45%, while having minimal impact on PM emissions and brake thermal efficiency. Therefore, it was concluded that B90DEC10 is a potential alternative to diesel, and the combustion performance and emissions control were optimized when using a higher EGR rate (15%).