The study represents a comprehensive analysis of engine exhaust emission variation from a compression ignition (CI) diesel engine fueled with diesel-biodiesel blends. Biodiesel used in this investigation was produced through transesterification procedure from Moringa oleifera oil. A single cylinder, four-stroke, water-cooled, naturally aspirated diesel engine was used for this purpose. The pollutants from the exhaust of the engine that are monitored in this study are nitrogen oxide (NO), carbon monoxide (CO), hydrocarbon (HC), and smoke opacity. Engine combustion and performance parameters are also measured together with exhaust emission data. Some researchers have reported that the reason for higher NO emission of biodiesel is higher prompt NO formation. The use of antioxidant-treated biodiesel in a diesel engine is a promising approach because antioxidants reduce the formation of free radicals, which are responsible for the formation of prompt NO during combustion. Two different antioxidant additives namely 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (MBEBP) were individually dissolved at a concentration of 1% by volume in MB30 (30% moringa biodiesel with 70% diesel) fuel blend to investigate and compare NO as well as other emissions. The result shows that both antioxidants reduced NO emission significantly; however, HC, CO, and smoke were found slightly higher compared to pure biodiesel blends, but not more than the baseline fuel diesel. The result also shows that both antioxidants were quite effective in reducing peak heat release rate (HRR) and brake-specific fuel consumption (BSFC) as well as improving brake thermal efficiency (BTE) and oxidation stability. Based on this study, antioxidant-treated M. oleifera biodiesel blend (MB30) can be used as a very promising alternative source of fuel in diesel engine without any modifications.
Neat waste plastic oil (WPO) application as a fuel in engines reduces BTE and increases deleterious emissions of CO, UHC, NOx, and smoke due to the presence of insufficient oxygen and unbreakable hydrocarbon chains in WPO. Present investigation was performed to evaluate the impact of ZnO nanoparticles on the performance and emission characteristics of a diesel engine operated with the waste plastic oil (WPO20) blend. The objective of doping ZnO nanoparticles with WPO20 was to enhance the oxidation reaction and heat transfer rate between fuel droplets during combustion, which aids in completing the combustion. The sol-gel technique was adopted to successfully synthesize the ZnO nanoparticles using zinc acetate (Zn(CH3CO2)2.2H2O) and sodium hydroxide (NaOH) precursors. The structure and morphology of resulted particles were studied by XRD and FESEM tests. Both results indicate the stable formation of ZnO, and exhibit the crystallinity nature, spherical surface, and size consistency. The synthesized ZnO nanoparticles were infused in WPO20 blend in the amounts of 50, 100, and 150 ppm with the aid of the ultrasonication technique. Engine test was conducted with diesel fuel, WPO20 blend, and nano-infused fuels at a constant speed of 1500 rpm under various loads. The disparities in performance and emission characteristics were examined and compared with pure diesel fuel. The findings demonstrated that adding nanoparticles to WPO20 significantly lowers the smoke, CO, UHC, and NOx emissions and simultaneously improves the BTE and decreases the BSFC of the diesel engine. Optimum results were obtained for 100 ppm concentration of ZnO nanoparticles. Reduction of smoke by 11.86%, CO by 5.7%, UHC by 28%, and NOx by 14.93%, along with the enhancement of BTE by 2.47%, were noticed at maximum load with 100 ppm particles. Based on the test results, it is concluded that ZnO nanoparticles can be used as a suitable additive in WPO blends to improve the overall engine characteristics. Further scope of the present work is to study the effect of organic nanoparticles with WPO on engine behaviour, the detailed combustion of nanoparticles infused WPO, and the nanoparticles doped WPO on engine wear and corrosion.