Temperature-Dependent Physical and Spray Characteristics of B50 Waste Cooking Oil Biodiesel

Abstract

This study investigated the effects of fuel temperature on the density, viscosity, spray angle, and spray length of B50 waste cooking oil biodiesel. Biodiesel was produced through degumming, esterification, and transesterification and then blended with diesel at a 50:50 volume ratio. Tests were conducted from 30 to 70°C. Increasing temperature reduced density from 832.9 to 788.5 kg/m³ and viscosity from 8.20 to 5.04 cSt. Concurrently, the spray angle increased from 3.52° to 7.13°, whereas spray length decreased from 488 to 442 mm. Linear regressions showed strong temperature relationships for density (R² = 0.991), viscosity (R² = 0.937), spray angle (R² = 0.959), and spray length (R² = 0.942). The results indicate that fuel heating lowers flow resistance and promotes wider radial dispersion while shortening axial penetration. These empirical relationships are limited to the investigated B50 formulation and temperature range.