Investigation the effects of adding hybrid nanoparticle on performance, combustion and emission characteristics of a diesel engine

In this thesis study, it is aimed to investigate the effects of using mono and hybrid nanoparticles on the combustion, performance and emission characteristics of a diesel engine. In this framework, three different types of nanoparticles (Al2O3, bN, and CuO) and their binary hybrid forms (CuO-Al2O3, bN-CuO, and bN-Al2O3) were doped into conventional diesel fuel (D100) at mass fractions of 250, 500, and 1000 ppm by using the ultrasonication method. In addition, the tests were carried out with conventional diesel fuel (D100) without nanoparticles and reference data were gathered. Tests were performed on a single-cylinder, air-cooled diesel engine, at a constant engine speed of 2400 rpm and varying engine loads of 3, 6, 9, 12 Nm. It is observed that nanoparticles increase the heating value, cetane number, and viscosity of diesel fuel. When the test engine was run with nanoparticles-doped test fuels, significant improvements were noticed in the engine's combustion, performance and emission characteristics. With the addition of nanoparticles, ignition delay duration shortened between 4.20% and 13.75%. Moreover, due to the fact that nanoparticles act as catalysts and accelerate chemical reactions during the combustion process, the average combustion duration (CD) shortened from 6.93% to 11.73%. Among all fuels, the shortest CD occurred for CuO-Al2O3 hybrid test fuel. On the other hand, the brake-specific fuel consumption (BSFC) and brake thermal efficiency (BTE) improved for all nanoparticle-containing test fuels. The largest reduction for the BSFC value was observed with the CuO-Al2O3 hybrid test fuel, where the CD was the shortest, at a rate of 11.08%, while the thermal efficiency for the same test fuel improved by 6.57%. The shortened CD, superior heat transfer mechanism, large surface/volume ratio, and improved engine performance ensured lower exhaust gas temperature as well as lower NOx emissions for nanoparticle-containing test fuels. With the addition of nanoparticles, the reduction rate for NOx emissions varied between 8.5% and 25.8%. Besides, incomplete combustion products such as CO and HC emissions were noticed to significantly drop for all nanoparticle-containing test fuels. While the average reduction for CO emissions was between 18.7% and 34.4%, this rate remained between 4.2% and 20.3% for HC emissions. Considering all results together, the use of nanoparticles along with conventional diesel fuel offers very promising results in terms of both energy efficiency and environmental aspects. In addition, it is noticed that the improvements in engine characteristics with the use of hybrid nanoparticles generally give better results than the use of mono nanoparticles.