Group contribution method for predicting viscosity of alkyl esters and biodiesel

People will need to use energy from sustainable sources more frequently to achieve neutral carbon emissions in the energy context transition in the close future. Biofuels are an interesting alternative to replace petroleum derived oils. Biodiesel is a mixture of alkyl esters got through vegetable oils or animal fats transesterification. The physical and chemical properties knowledge of biodiesel is essential to define its quality and well performance in automotive engines. Viscosity is one of the most important properties of biodiesel because it plays a significant role in the combustion and transport processes. This study compiled viscosity data from literature for a total of 45 alkyl esters, encompassing 931 experimental data points, as well as 24 biodiesel samples and 32 biodiesel binary mixtures, accounting for 566 experimental data points. These compiled viscosities were then utilized to assess the effectiveness of a group contribution approach, yielding a viscosity prediction with an average absolute deviation (AAD) of 4.37 % and a correlation coefficient (R) of 0.9942. Furthermore, the Grunberg-Nissan mixing rule was employed to estimate the viscosity of biodiesel, resulting in an AAD and R of 5.89 % and 0.9859, respectively.Finally, the method proposed here is easy to implement and useful for many applications.