Application of mixture topological index method to predict the dynamic viscosity of the hypothetical acidic oils-based biodiesel fuels

This work proposed a method to predict the dynamic viscosity values of the hypothetical acidic oils-based biodiesel fuels. A topological index that can formulate the molecular structural information of fatty acid methyl ester (FAME) components into dimensionless form was built from the integration and modification of the distance matrix and adjacency matrix of the molecular structure. Results show that both the caprylic acid (C8:0) and linoleic acid (C18:2) are beneficial components for reducing the biodiesel fuel’s dynamic viscosity. Nine hypothetical acidic oils-based biodiesel fuels were made from the mixing of C8:0 or C18:2 with one vegetable oil at the same mass ratio, including peanut, canola, coconut, palm, soybean, corn, rapeseed, sunflower and cottonseed oils, and the dynamic viscosity values of them were predicted. The dynamic viscosity values were ranged at 0.90–2.13 mPa s (with the addition of C8:0) and 2.83–4.07 mPa s (with the addition of C18:2). This investigation is expected to provide some suggestions for the selection of some components that are beneficial for reducing the product’s dynamic viscosity, so that the atomization characteristic of a low-quality feed can be improved by adding some suitable components into it.