Winterisation of waste cooking oil methyl ester to improve cold temperature fuel properties

Waste cooking oil methyl ester (WCOME) was winterised at 1, 0, −1 and −2°C following a 4×2 factorial design with one replication per cell. The process was carried out by filtration and both the filtrate (solid phase) and the liquid phase were analysed by gas chromatography (GC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Cold filter plugging point (CFPP) and calorific values were measured.Temperatures of 0 and −1°C in conjunction with the quickest cooling rate (0.1°C min⁻¹) and 15-24 h of cooling gave the most successful results in terms of fuel properties.Improvements in the low temperature properties of the winterised fuel were reflected by a reduction of saturated fatty acid methyl esters (SFAME) in the composition by 1.5-6%, by a decrease in the CFPP values by 2-4°C and by a shift of the DSC high temperature melting peak (approx. 5°C) towards lower temperatures in comparison to the original fuel. Calorific values of the winterised WCOME did not significantly change and boiling temperatures increased (approx. 26%) in comparison to the non-winterised WCOME.