Estimation of Density of Biodiesel

Density of biodiesel is an important physical property of liquid fuel and biodiesel. A slight change in density can affect engine output power. In this work, density of a saturated, unsaturated fatty acid methyl ester or a biodiesel can be estimated from either (1) its number of carbon atoms (of fatty acid, z) and number of double bonds (n d): ln ρ = −0.435 – 0.0025z + 85.98/T + 0.792z/T + 4.0 n d/T or (2) its saponification number (SN) and iodine value (IV): ln ρ = −0.427 – 10/SN + 83.38/T + 3168.95/(T × SN) + 11 IV/(T × SN), where T is absolute temperature. The predicted densities at different temperatures from both equations agree well with the reported literature values.