FME Transactions (Jan 2020)
Theoretical prediction of thermo-physical properties of beef tallow based biodiesel
Abstract
This present study deals with the theoretical prediction of thermo-physical properties of waste beef tallow biodiesel by means of developing mathematical correlations using fatty acid esters. Waste beef tallow was rendered from animal slaughter houses and tanneries' leather fleshing wastes; and was transesterified into biodiesel through base catalyzed ethanolysis. Ethyl palmitate (C16:0), ethyl oleate (C18:1) and ethyl stearate (C18:0) were identified as the dominant fatty acid ethyl esters (FAEs) in the tallow biodiesel, with their corresponding distribution as 37.36%, 25.17% and 14.78% respectively. Mathematical correlations were developed for predicting density, kinematic viscosity, cetane number and higher heating value using statistical regression by maintaining molecular weight (Mwt) and number of unsaturated bonds (NE) of FAEs as input variables. Overall, thermo-physical properties of the biodiesel were computed from the properties calculated using the correlations, mass fraction and mole fraction of characterized FAEs; and was compared with the experimental data determined according to ASTM D976 standards. Accordingly, the average absolute deviation (AAD) and average Absolute Percentage Error (AAPE) were calculated as 3.55, 0.815% for density; 0.12, 4.79% for kinematic viscosity; 2.14, 6.56% for cetane number and 0.23, 1.14% for higher heating value respectively. From these correlations, it showed that kinematic viscosity, cetane number and higher heating value increased with molecular weight of the FAEs but reduced with increase in unsaturation; in contrast, density of biodiesel increased with its unsaturation but decreased with increasing molecular weight. In conclusion, the predicted values of density, kinematic viscosity, cetane number and higher heating value were found to be in reasonable agreement with experimental values.
