Effect of Pre-Injection on Combustion and Emission Characteristics of a Diesel Engine Fueled with Diesel/Methanol/n-Butanol Blended Fuel

In this study, the combustion and emission characteristics of a diesel/methanol/n-butanol blended fuel engine with different pre-injection timings and pre-injection mass ratios were investigated by a computational fluid dynamics (CFD) model. The CFD model was verified by the measured results and coupled with a simplified chemical kinetics mechanism. Firstly, the corresponding three-dimensional CFD model was established by CONVERGE software and the CHEKMIN program, and a chemical kinetic mechanism containing 359 reactions and 77 species was developed. Secondly, the combustion and emission characteristics of the diesel engine with different diesel/methanol/n-butanol blended fuels were analyzed and discussed. The results showed that increases in the pre-injection timing and the pre-injection mass ratio could increase cylinder pressure and cylinder temperature and decrease soot, HC, and CO emissions. At 100% load, the maximum cylinder pressures at the start of pre-injection timing from −15 °CA to −45 °CA, were 7.71, 9.46, 9.85, 9.912, and 9.95 MPa, respectively. The maximum cylinder pressures at pre-injection fuel mass ratios from 0.1 to 0.9 were 7.98, 9.10, 9.96, 10.52, and 11.16 MPa, respectively. At 50% load, with increases of the pre-injection timing and pre-injection fuel mass ratio, the soot emission decreased by 7.30%, 9.45%, 27.70%, 66.80%, 81.80% and 11.30%, 20.03%, 71.32%, 83.80%, 93.76%, respectively, and CO emissions were reduced by 5.77%, 12.31%, 22.73%, 53.59%, 63.22% and 8.29%, 43.97%, 53.59%, 58.86%, 61.18%, respectively. However, with increases of the pre-injection timing and pre-injection mass ratio, NOx emission increased. In addition, it was found that the optimal pre-injection timing and optimal pre-injection mass ratio should be −30 °CA and 0.5, respectively. Therefore, through this study we can better understand the potential interaction of relevant parameters and propose pre-injection solutions to improve combustion and emission characteristics.

Justification of the Reduction Possibility of Sulfur Oxides and Fly Ash Emissions during Co-Combustion of Coal and Waste from Woodworking Enterprises

In this work, we experimentally investigated the effect of widespread biomass (woodworking waste—pine sawdust) in the composition of mixed fuel, formed also using the widespread steam coals metalignitous (D) and lean (T), on the concentration of sulfur, nitrogen and carbon oxides in flue gases. Investigations of composite fuels with a mass of at least 5 g were carried out in a reactor with continuous recording of the composition of the flue gases formed during the thermal decomposition of the investigated fuels. Thermal decomposition of fuels was carried out in the temperature range from 293 K to 873 K. It was found that an increase in the proportion of wood components in mixed fuels based on two different coals from 10% to 50% leads to a significant decrease in the concentration of sulfur oxides from 11% to 95.8% relative to the concentration of the formation of sulfur oxides in a homogeneous coal, respectively. It was found that an increase in the proportion of the wood component in the mixture with grade D coal up to 50% leads to a significant increase in the content of calcium sulfates (45.1%) and aluminum (43.2%) in the blended fuel. The increase in the content of these salts in the ash of mixed fuels based on T coal and wood is 35.1% and 38.6%, respectively. The obtained research results allowed us to conclude that woodworking wastes are an effective addition to the coals of various deposits, which would help to reduce anthropogenic-induced gas emissions when they are co-combusting in the furnaces of power boilers.

Investigation of the Performance and Emission Characteristics of a Diesel Engine with Different Diesel–Methanol Dual-Fuel Ratios

In this paper, the effects of different diesel–methanol blends on the combustion and emission characteristics of diesel engines are investigated in terms of cylinder pressure, heat release rate, cylinder temperature, brake specific fuel consumption, thermal brake efficiency, brake power, and soot, nitrogen oxides, and carbon monoxide emissions in a four-stroke diesel engine. The corresponding three-dimensional Computational Fluid Dynamics (CFD) model was established using the Anstalt für Verbrennungskraftmaschinen List (AVL)-Fire coupled Chemkin program, and the chemical kinetic mechanism, including 135 reactions and 77 species, was established. The simulation model was verified by the experiment at 50% and 100% loads, and the combustion processes of pure diesel (D100) and diesel–methanol (D90M10, D80M20, and D70M30) were investigated, respectively. The results showed that the increase in methanol content in the blended fuel significantly improved the emission and power characteristics of the diesel engine. More specifically, at full load, the cylinder pressures increased by 0.78%, 1.21%, and 1.41% when the proportions of methanol in the blended fuel were 10%, 20%, and 30%, respectively. In addition, the power decreased by 2.76%, 5.04%, and 8.08%, respectively. When the proportion of methanol in the blended fuel was 10%, 20%, and 30%, the soot emissions were decreased by 16.45%, 29.35%, and 43.05%, respectively. Therefore, methanol content in blended fuel improves the combustion and emission characteristics of the engine.

Combustion characteristics of coal, petroleum coke, biomass and their ternary blends

This work presents the combustion characteristics of coal, petroleum coke (PC), rice straw (RS), mustard cake (MC) and their blends to assess the applicability of blended fuel for thermal power generation. Characterization results show that PC has the highest GCV (35990 kJ/kg) to improve the overall energy density of the blend significantly. Higher VM present in RS and MC improved the ignition behavior and combustion efficiency of the blend. For 10 OC/min heating rate at 350 OC, with the increase in RS in blends from 10% to 30%, combustion efficiency increased from 12.85% to 32.66%. Synergistic analysis signifies that higher biomass content enhances blends' combustion characteristics through catalytic effects of alkali oxides present in RS/MC. Thermodynamic analysis (ΔH, ΔG and ΔS) inferred that RS and MC combustion is easier than coal and PC. With the increase in MC in blends from 10% to 30%, ΔH decreased from 114.81 to 82.31 kJ/mol, ΔG declined from 159.33 to 122.86 kJ/mol and ΔS improved from −63.59 to −58.14 J/mol.K, indicating blending of biomass improved the combustion.