Comparative evaluation of nanoparticle-enriched Gossypium hirsutum methyl ester blends for enhanced energy, emission, and economic performance in diesel engines

This study examines the comparative effectiveness of different nanoparticles, metal-based (CuO), carbon-based (CNTs), and their composites (CuO-CNTs), in enhancing the energy and environmental characteristics of a diesel engine propelled with Gossypium hirsutum methyl ester (GHME). A high GHME yield of 96 % was achieved under optimized transesterification conditions, and its physicochemical properties were comprehensively characterized. A 30 % volumetric blend of GHME with plain diesel fuel (PDF), denoted as PDF30GHME, was prepared and enriched with 100 ppm of CuO, CNTs, and CuO-CNT nanocomposites using ultrasonication. The energy, environmental, and economic characteristics of these test fuels was assessed using a standalone research diesel engine. Nanoparticle characterization revealed improved catalytic and thermal properties, enhancing the combustion process and thermal efficiency. The base fuel blend, PDF30GHME, exhibited a 3.9 % upsurge in brake-specific fuel consumption and a 6.6 % reduction in brake thermal efficiency related to plain diesel. Emission analyses showed reductions in hydrocarbon, carbon monoxide, and smoke opacity emissions by 4.6 %, 7.8 %, and 6.4 %, respectively, although nitrogen oxides (NOx) emissions increased by 2.7 %. Nanoparticle-enriched PDF30GHME significantly improved both performance and emission metrics. Carbon-based additives demonstrated superior enhancements in engine performance and emissions reduction, while metal-based additives were particularly effective in minimizing NOx emissions. Economic analysis revealed that CuO-enriched PDF30GHME achieved the highest cost reduction, lowering fuel costs by 5.42 %. The CuO-CNT composite emerged as the most promising additive, offering a balanced improvement in performance, emissions, and cost-effectiveness, positioning it as a viable candidate for sustainable and cleaner diesel engine operations.