Effects of biodiesel degree of unsaturation, chain length and physical properties on tailpipe oxides of nitrogen (NOx)

Biodiesel degree of unsaturation and chain length have impacts on the NOx emissions in engines. This work presents experimental investigation of the effects of biodiesel degree of unsaturation (numbers of double bonds), chain length and physical properties on NOx emissions. A methodology to decouple the effects of degree of unsaturation and chain length is presented. Results shows that NOx emissions found to increase as the degree of unsaturation increases, peaking at an average degree of unsaturation of 1.5. Shorter chain length esters found to produce lower NOx emissions which were found to decrease until the chain length factor of 0.765 was reached. Finally, NOx emissions with biodiesel para-anisidine (pA), peroxide value (PV), total oxidation (TOTOX), conjugated dienes (CD), the oxidative stability index (OSI), Viscosity, Iodine number, bis-allylic position equivalents (BAPE) is presented.