Combustion and Emission Characteristics of Biodiesel with Methyl Butanoate as Surrogate.

摘要

Combustion and emission characteristics of compression ignition engines depend strongly on inner-nozzle flow and spray behavior. These processes control the fuel-air mixing, which in turn is critical for the combustion process. Previous studies by us have highlighted the differences in the physical and chemical properties of petrodiesel and biodiesel, which significantly altered the inner-nozzle flow and spray structure. The current study is another step in this direction to gain understanding on the influence of fuel properties on the combustion and emission characteristics of the compression ignition engine. Nheptane and methyl butanoate were selected as surrogates for diesel and biodiesel fuel respectively, since the chemical kinetic pathways were well understood. Liquid length and flame liftoff length for diesel and biodiesel fuels were validated against data available in literature. Biodiesel predicted lower soot concentrations. Although prompt NOx was higher for biodiesel, total NOx was lower due to reduced thermal NOx. The ignition delay and NOx emissions predicted by these simulations do not agree with trends reported in literature; hence, this study highlights the need for developing better fuel surrogates for diesel and biodiesel fuels.