Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
Burning fuels in an O2/H2O atmosphere is regarded as the next generation of oxy-fuel\ncombustion for CO2 capture and storage (CCS). By combining oxy-fuel combustion and biomass\nutilization technology, CO2 emissions could be further reduced. Therefore, this work focuses\non investigating the combustion characteristics of single particles from bituminous coal (BC) and\npine sawdust (PS) in O2/N2, O2/CO2 and O2/H2O atmospheres at different O2 mole fractions\n(21%, 30%, and 40%). The experiments were carried out in a drop tube furnace (DTF), and a high-speed\ncamera was used to record the combustion processes of fuel particles. The combustion temperatures\nwere measured by a two-color method. The results reveal that the particles from BC and PS all\nignite homogeneously. Replacing N2 by CO2 results in a longer ignition delay time and lower\ncombustion temperatures. After substituting H2O for N2, the ignition delay time is shortened,\nwhich is mainly caused by the steam gasification reaction (C + H2O ââ? â?? CO + H2) and steam shift\nreaction (CO + H2O ââ? â?? CO2 + H2). In addition, the combustion temperatures are first decreased at\nlow O2 mole fractions, and then increased at high O2 mole fractions because the oxidation effect\nof H2O performs a more important role than its volumetric heat capacity and thermal radiation\ncapacity. At the same condition, particles from PS ignite earlier because of their higher reactivity,\nbut the combustion temperatures are lower than those of BC, which is owing to their lower\ncalorific values....
The stratification of in-cylinder mixtures appears to be an effective method for managing\nthe combustion process in controlled auto-ignition (CAI) engines. Stratification can be achieved and\ncontrolled using various injection strategies such as split fuel injection and the introduction of a\nportion of fuel directly before the start of combustion. This study investigates the effect of injection\ntiming and the amount of fuel injected for stratification on the combustion and emissions in CAI\nengine. The experimental research was performed on a single cylinder engine with direct gasoline\ninjection. CAI combustion was achieved using negative valve overlap and exhaust gas trapping.\nThe experiments were performed at constant engine fueling. Intake boost was applied to control the\nexcess air ratio. The results show that the application of the late injection strategy has a significant\neffect on the heat release process. In general, the later the injection is and the more fuel is injected for\nstratification, the earlier the auto-ignition occurs. However, the experimental findings reveal that the\neffect of stratification on combustion duration is much more complex. Changes in combustion are\nreflected in NOX emissions. The attainable level of stratification is limited by the excessive emission\nof unburned hydrocarbons, CO and soot....
The purpose of this paper is to conduct experimental research of hazardous substance emissions at the simulated combustion\nchamber output. The experiment was carried in a simulated combustion chamber. The combustion chamber included a burner\ndevice; a liquid fuel feed system; and a flame tube with two rows of mixing holes and one row of cooling holes. The combustion\nchamber operation mode was ...
Based on the theory of direct relation graph (DRG) and the sensitivity analysis, a reduced mechanism for the diesel-syngas dual\nfuel was constructed. Three small thresholds were applied in the process of the detailed mechanism simplification by DRG, and\na skeletal mechanism with 185 elements and the 832 elementary reactions was obtained. According to the framework of the\nskeletal mechanism, the time-consuming approach of sensitivity analysis was employed for further simplification, and the skeletal\nmechanism was further reduced to the size of 158 elements and 705 reactions.The Chemkin software with the detailed mechanism\nwas utilized to calculate the effect of syngas addition on the combustion characteristics of diesel combustion. The findings showed\nthat the addition of syngas could reduce the ignition delay time and increase the laminar flame speed. Based on the reduced\nmechanism and engine parameters, a 3D model of the engine was constructed with the Forte code. The 3D model was adopted to\nstudy the effect of syngas addition on the performance and exhaust emissions of the engine and the relevant data of the experiment\nwas used in the calibration of the 3D model....
To safely mine coal, engineers must prevent gas combustion and explosions, as well as\nseek feasible and reasonable techniques to control for these types of incidents. This paper analyzes\nthe causes and characteristics of methane combustion and explosions. Water mist is proposed to\nprevent and control methane combustion in an underground confined space. We constructed an\nexperiment platform to investigate the suppression of methane combustion using water mist for\ndifferent conditions. The experimental results showed that water mist is highly effective for methane\nflame inhibition. The flame was extinguished with water mist endothermic cooling. However,\nthe annular regions of water vapor around the fire played a vital role in flame extinction. Water from\nthe evaporating mist replaces the oxygen available to the fuel. Additionally, the time required for\nfuel ignition is prolonged. For these reasons, the water particle action to flame surface is reinforced\nand the fuel�s reaction with air is delayed. As a result, flame stretching and disturbances occur, which\nserve to extinguish the flame. Engineering application tests were carried out in the goaf, drill hole\nand upper-corner to investigate the prevention and control of methane gas combustion, with the\nresults showing a good application effect....
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