Effects of metal-oxide nanoparticles and biodiesel mixtures on combustion, performance, emissions, vibration, and noise parameters in a Variable Compression Ratio (VCR) diesel engine
Krupa Sulakhi, Arun Raaza, M. Anish, Jayant Giri, Amanullah Fatehmulla, J.R. Deepak, J. Aravind Kumar
Abstract
This study examines the effect of metal-oxide nanoparticles (CeO 2 , MgO, MnO 2 ) on the emission, combustion, performance, and NVH characteristics of a VCR diesel engine operating on Freshwater Algae Oil Butyl Ester blends (B20). Engine tests at 2500 rpm across four loads (25–100 %) revealed that nanoparticle doping (100 ppm) significantly improved fuel properties and combustion efficiency. The most striking finding was an 81.34 % reduction in hydrocarbon (HC) emissions with the addition of MnO 2 , the highest reported improvement among contemporary biodiesel-nanofuel studies. CeO 2 -doped blends achieved comparable CO reductions, while NOx emissions slightly increased due to higher combustion temperatures. Performance enhancements included a 4.6 % improvement in brake thermal efficiency (BTE) and a decrease in brake-specific fuel consumption (BSFC) across all nano-additives. Combustion analysis revealed a 3.8 % increase in peak cylinder pressure (CPmax) and a 4.2 % higher heat release rate (HRRmax), attributed to improved atomization and catalytic effects. Notably, nanoparticle additives also reduced engine vibration and noise levels by up to 15 %. These results demonstrate that metal-oxide nanoparticles, particularly MnO 2 , can simultaneously optimize emissions, performance, and operational smoothness in biodiesel-diesel blends, with the unprecedented HC reduction offering a breakthrough for clean combustion strategies. • Metal-oxide nanoparticles added to biodiesel mixes enhance the fuel's atomization and combustion efficiency, resulting in increased energy production. • Metal-oxide nanoadditives in biodiesel aliquots reduce HC, CO, and NOx emissions by enhancing combustion and mitigating pollution. • The spray properties are enhanced because NPs enhance atomization precision. • The investigation concluded that metal-oxide nanoparticles minimize engine vibration and noise.