Bioenergy and biofuels are at a critical stage of development. Their role in decarbonising the transport sector, particularly in reducing emissions from shipping and aviation, is widely recognized. Waste Cooking Oil Biodiesel (WCOB) is a promising biofuel, due to its economic viability and sustainability. Additionally, oxygenated additives, such as Dibutyl Ether (DBE), enhance the properties of biofuel blends by improving combustion efficiency and reducing emissions. In this study, the density of WCOB and DBE, was systematically investigated under controlled temperature and pressure conditions. Four mixtures with mass fractions of 0.3500, 0.4998, 0.6750, and 0.8492 were prepared. Density measurements were performed over a temperature range of 298.15 K–393.15 K and a pressure range of 1–140 MPa. The Tait equation was used to correlate the experimental density data, which were subsequently used to determine the derived thermodynamic properties of isobaric expansion and isothermal compressibility. The blend density was also predicted using the PC-SAFT equation of state and artificial neural networks (ANN). Models accuracy was evaluated and discussed using a statistical metrics. The ANN model provided the best accuracy for the complete dataset, with AAD = 0.1246 %, MD = 2.3046 % and RMSE = 1.84.10−3, demonstrating its effectiveness in predicting blend densities.
