Abstract
Air pollution, climate changes, and global warming are strongly correlated with burning huge amounts of petroleum fuels. Biodiesel has emerged as a promising alternative to alleviate these problems. Nonetheless, high density and viscosity, low energy content, and poor atomization of biodiesel restrict its widespread usage in diesel engines. The addition of nanoparti-cles (NPs) in biodiesel-based fuels has recently received considerable attention to modify the physicochemical properties of fuel as well as to improve the performance and emission characteristics of diesel engines. Among the various NP additives, alumina (Al 2 O 3) NPs are of high interest owing to their excellent chemical and thermal stability, nontoxicity, high catalytic activity, etc. Hence, the present paper attempts to review the available literature concerning biodiesel fuels containing Al 2 O 3 NPs. In this regard, the preparation techniques and physiochemical properties of these fuels including density, kinematic viscosity , cetane number, flash point, and calorific value are first discussed. Furthermore, the impact of Al 2 O 3 NPs on the spray atomization and evaporation features of as-used fuels is investigated. Finally, the performance, combustion, and emission characteristics of diesel-fueled engines with Al 2 O 3 NP-added biodiesel fuels are assessed. In conclusion, it was found that the use of Al 2 O 3 NPs in biodiesel fuels can lead to enhanced engine performance by increasing the brake thermal efficiency, decreasing brake-specific fuel consumption, and lowering the emission of various harmful pollutants. Graphical abstract The performance of Al 2 O 3 nanoadditives for biodiesel-fueled diesel engines