Advancements in the Thermo-Physical Enhancement of Automotive Biofuels Through Nanomaterials: A Comprehensive Review

Biofuels are renewable alternatives to fossil fuels, but their performance in engines is often limited by suboptimal thermo-physical properties such as high viscosity, low thermal conductivity, and less favorable combustion characteristics. Nanomaterials have emerged as potent additives to overcome these limitations, owing to their high surface area, catalytic activity, and unique size-dependent properties. This review provides a comprehensive analysis of how various nanomaterials – including carbon nanotubes, metallic nanoparticles (e.g., Al₂O₃, TiO₂, CeO₂), graphene, and metal oxides – enhance the thermo-physical properties of automotive biofuels to improve combustion efficiency, engine performance, and emissions profiles. We discuss the fundamental mechanisms by which nanoparticles improve fuel thermal conductivity, reduce viscosity, catalyze combustion, and stabilize fuel mixtures. The review synthesizes findings from recent studies demonstrating improvements such as increased brake thermal efficiency, reduced brake-specific fuel consumption, and significant reductions in harmful emissions like unburnt hydrocarbons and carbon monoxide with nano-enhanced biofuel blends. Additionally, challenges including nanoparticle dispersion stability, cost, potential environmental and health impacts, and the lack of standardized regulations for nano-enhanced fuels are critically examined. Recent advancements in nanoparticle functionalization and composite additives are highlighted as strategies to mitigate these challenges. Future prospects are outlined with an emphasis on sustainable implementation, including the potential benefits for organizations like the Bangladesh Army in terms of energy security and performance. Overall, nanomaterial additives offer a promising pathway for thermo-physical enhancement of biofuels, driving cleaner and more efficient automotive fuel applications.