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The use of hydrogen can be a potential solution to reduce high CO and unburnt HC emissions, which is one of the most critical challenges, from Reactivity Controlled Compression Ignition (RCCI) engines at low loads as it is a very clean and carbon-free fuel candidate for internal combustion engines. Therefore, the aim of this study is designed to investigate numerically the effect of the hydrogen share on combustion characteristics in a diesel research engine operated in RCCI mode. The engine is fueled with conventional diesel and iso-octane enriched with hydrogen and is operated at 20% of the maximum torque (low load) and 2400 rpm. A 40% of conventional diesel (in the case of conventional diesel mode (CDM), its share was 100%) is injected per cycle into cylinder of the engine, while varying proportions of iso-octane (60% to 12%) and hydrogen (0% to 48%) are sprayed into the air from the intake manifold. Both CDM and RCCI combustion models built by 3D scanning of the existing engine using reverse engineering to computational fluid dynamic (CFD) was simulated through ANSYS-Forte coupled with a chemical kinetics solver (Chemkin-Pro). The simulation results showed that by adding hydrogen to iso-octane in RCCI mode, the proportion of hydrogen could be increased up to 48% while improving thermal efficiency by 33.3% in comparison with 24.9% with RCCI without hydrogen addition. Therefore, the overall hydrocarbon fuel consumption per cycle was reduced by up to 47.52%. Hydrogen addition resulted in a higher concentration of OH species in the flame front, and higher pressure and temperature in the cylinder, in turn, contributed to an increase in NOx emissions considerably but led to decrease in CO/HC emissions of RCCI operation. The decrease in the emissions of CO, HC, and C2H2 of up to 64.6, 81.8, and 76.6%, respectively, was observed by using 48% of H2 in RCCI mode compared to RCCI mode without hydrogen addition. It was concluded that high CO and unburned HC emissions from RCCI combustion. This research provides promising contributions to the literature for using hydrogen in substitution of hydrocarbon fuels and reducing emissions from RCCI engines. [ABSTRACT FROM AUTHOR]

The correlation between oxides of nitrogen emission and in-cylinder temperature of diesel engine fueled with various alternative fuels has been investigated in this research paper. Experimentations were performed in engine without any modifications using pure high-speed diesel fuel, used cooking oil biodiesel (UCO20), animal fat residue biodiesel (AFR20) and camphor oil (CMR20) at 20% volume concentration of biodiesel each. From combustion analysis, the heat release rate and peak cylinder pressure of biodiesel blends were about 13.487% lower and 4.819% higher than those of diesel fuel on an average, respectively. Longer combustion duration has been observed for all biodiesel blends at all load conditions. Oxides of nitrogen emission level show 16.405, 10.352 and 7.524% increment for UCO20, AFR20 and CMR20, respectively. Noteworthy NO reduction of about 43.8% was recorded for diesel blended with camphor oil when compared to other biodiesel blends. The relationship between in-cylinder temperature and NO emission concentration was premeditated through thermal imager. The result depicted that the increase in NO concentration depends on augmented in-cylinder temperature for all test fuels. [ABSTRACT FROM AUTHOR]

Due to the shortage of petroleum products and its increasing cost, efforts are on to develop alternate fuels, especially diesel oil, for partial or full replacement. Also, internal combustion engines generate undesirable emissions during combustion process. The emissions exhausted in to the surroundings pollute the atmosphere and causes several problems. The emissions of concern are: unburnt hydrocarbons, oxides of carbon, and oxides of nitrogen (NO X). Advanced diesel fuel formulations offer significant emission reductions to new and older in-use engines every time the fuel tank is filled. The addition of water to diesel fuel lowers particulate emissions by serving as diluents to the key combustion intermediates that lead to particulate formation. The incorporation of water also reduces NO X emissions by lowering the peak combustion temperatures through high heat of vaporization. When using water blend diesel, the engine fuel system recognizes the liquid as diesel fuel because the water droplet is encapsulated within a diesel fuel. In this experiment, we have used single cylinder four-stroke engine and the water-blend diesel emulsion is used and the diesel emission test, emulsion emission test, and various gases has been analyzed; smoke meter test is also conducted for various rate of loads. The test results from the engine fuelled with water-blend diesel showed reduction in emissions as compared to that of engine fuelled with conventional diesel. The better emissions in the CI engine using water-blend diesel is due to the incorporation of water which reduces NO X emissions by lowering the peak combustion temperatures. Water-blend fuel enhances fuel atomization by micro-explosion. The addition of water to diesel fuel lowers particulate emissions by serving as diluents to the key combustion intermediates that lead to particulate formation [ABSTRACT FROM AUTHOR]