Semnan University Press Journal of Heat and Mass Transfer Research 2345-508X 13 2 2026 06 01 Experimental Optimization of Hybrid Nanoparticle-Enhanced Biodiesel–Diesel Blends for Engine Performance and Fuel Stability بهینه‌سازی تجربی مخلوط‌های هیبریدی بیودیزل-دیزل تقویت‌شده با نانوذرات برای بهبود عملکرد موتور و پایداری سوخت 175 192 9857 10.22075/jhmtr.2025.37866.1758 EN Seyed Amir Hossein Zamzamian Energy Department, Materials and Energy Research Center(MERC), Karaj, Iran Marjan Mehrali Energy Department, Materials and Energy Research Center(MERC), Karaj, Iran Journal Article 2025 05 24 This study investigates the effects of hybrid nanoparticles on the properties and performance of nano-biodiesel-diesel blends. Four types of nanoparticles (Al₂O₃, SiO₂, CuO, and Co₃O₄) were studied to determine the most stable hybrid nanofuel compositions. The biodiesel was produced from waste cooking oil using a transesterification method with methanol at a 9:1 molar ratio and potassium hydroxide as a catalyst. Five fuel blends were prepared and tested: pure diesel (D<sub>100</sub>), pure biodiesel (B<sub>100</sub>), B<sub>20</sub> (20% biodiesel + 80% diesel), and two hybrid nanofuel blends (B<sub>20</sub>AS<sub>40</sub> and B<sub>20</sub>ASCC<sub>40</sub>) containing different combinations of nanoparticles. Comprehensive physicochemical property analyses and engine performance tests were conducted. The results demonstrate significant improvements in fuel properties and engine performance. The calorific value increased by 7% for B<sub>20</sub>AS<sub>40</sub> and 9% for B<sub>20</sub>ASCC<sub>40</sub>, compared to pure diesel. Brake specific fuel consumption decreased by 15% and 14%, respectively, for these nanofuel blends, while brake thermal efficiency improved to 31.1% and 32.0%, compared to 30.0% for pure diesel. These findings confirm that hybrid nanoparticles can effectively enhance fuel properties and engine performance when properly combined with biodiesel-diesel blends. The research provides valuable insights into developing more efficient and environmentally friendly fuel alternatives for diesel engines. Emission parameters such as NO<sub>x</sub>, CO, and HC were not within the scope of this experimental setup and were therefore not measured. hybrid nano fuel Nanomaterial nano biodiesel Physicochemical properties Diesel Engine https://jhmtr.semnan.ac.ir/article_9857_04a5e33bc793f01b85e4abec92476fdc.pdf