共查询到20条相似文献,搜索用时 187 毫秒
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利用CFD软件,基于ISAT算法和简化的甲烷氧化基元反应模型,建立了CH4-O2-N2预混气体的二维湍流爆炸模型。数值计算结果表明,该模型较好地模拟了CH4-O2-N2预混气体在高温气团作用下的点火、燃烧和爆炸过程。计算中,考察了高温点火气团的初始温度和混合气体初始组分对CH4-O2-N2预混气体燃烧和爆炸过程的影响。结果表明:高温气团的初始温度对CH4-O2-N2预混气体的点火延迟时间和燃烧初始阶段有重要影响,但对CJ爆燃没有影响;惰性气体N2的加入,降低了混合气体的反应活性,导致点火延迟时间增大,燃烧反应速度、爆炸超压和重要自由基浓度都随之减小。相同条件下爆炸超压峰值的计算结果与实验测量结果符合较好。 相似文献
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利用二级轻气炮在3.75~57.87 GPa 压力范围内,对体积比为10∶10∶1的液态水-苯-壬基酚聚氧乙烯醚混合体系进行了动高压加载实验,获得了10个Hugoniot数据。拟合结果表明,该混合体系的D-u关系可近似用直线方程D=1.407+1.503up描述,拟合精度约为0.102。混合体系H2O-C6H6-C35H64O11的冲击压缩实验结果基本符合体积相加原理,而在给定的实验压力区间内,冲击绝热曲线发生多次拐折的事实意味着该系统可能在6 GPa、10 GPa和30 GPa压力点附近发生了多次结构性相变。另外,还讨论了Lawrence-Berthlot混合规则中修正因子对高密度条件下指数-6型相互作用势排斥部分的影响。 相似文献
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利用甲醇-氢(CH3OH-H2)混合气体为气源,30 nm厚的无定形硅为过渡层,借助于微波等离子体化学气相沉积(MWCVD)成功地将金刚石薄膜生长在不锈钢上,其最低生长温度可至420 ℃,并且甲醇-氢混合气体比传统的甲烷-氢(Ch4-H2)更具优势,测试表明这种金刚石薄膜有希望作为耐磨层在工业上应用。 相似文献
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A.C. Cefalas N. Vassilopoulos E. Sarantopoulou Z. Kollia C. Skordoulis 《Applied Physics A: Materials Science & Processing》2000,70(1):21-28
We report on the mass spectroscopic and the laser ablative characteristics of nylon 6.6 [-NH-(CH2)6-NH-CO-(-CH2)4-CO-] at 193 and 248 nm, using the ArF and KrF excimer lasers. The characteristic parameters of the laser ablative process, such as etch rate at different fluences, the threshold fluence, and the absorption coefficient for both wavelengths were determined. Even at low laser energy, there was a complete breaking of the polymeric chain bonds. The following photofragments were observed at 248 nm: H, H2, C, CH, CH2, N, NH, O, OH, H2O, C2H, C2H2, CN, C2H3, HCN, N2, CO, C2H4, COH, C2H5, N2H, NO, C2H6, H2CO, N2H2, C2, CH2NH, O2, C3H3, C3H4, C3H5, C3H6, CNO, HCNO, and H2CNO. At 193 nm no photofragments were observed for m/e larger than 30 amu. The photofragments with two carbon atoms have a relatively higher probability to be dissociated from the parent monomer, than heavier photofragments with four carbon atoms. The mass spectroscopic studies and the absorption spectrum of nylon 6.6 in the ultraviolet, suggest photochemical bond-breaking at 248 and 193 nm. The monomer dissociates into fragments with the predominant mass at 28 amu for both laser wavelengths. Therefore the amide group is mainly involved in the photodissociation process of nylon 6.6 in the ultraviolet. The experimental results suggest that the photochemical dissociation of the polymeric chain is the dominant mechanism of the laser ablation of nylon 6.6 at 193 and 248 nm. 相似文献
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Hamid Hashemi Jakob M. Christensen Paul Marshall Peter Glarborg 《Proceedings of the Combustion Institute》2021,38(1):269-278
A detailed chemical kinetic model for oxidation of CH3CHO at intermediate to high temperature and elevated pressure has been developed and evaluated by comparing predictions to novel high-pressure flow reactor experiments as well as shock tube ignition delay measurements and jet-stirred reactor data from literature. The flow reactor experiments were conducted with a slightly lean CH3CHO/O2 mixture highly diluted in N2 at 600–900 K and pressures of 25 and 100 bar. At the highest pressure, the oxidation of CH3CHO was in the NTC regime, controlled to a large extent by the thermal stability and reactions of peroxide species such as HO2, CH3OO, and CH3C(O)OO. Model predictions were generally in good agreement with the experimental data, even though the predicted temperature for onset of reaction was overpredicted at 100 bar. This discrepancy was attributed mainly to uncertainties in the CH3C(O)OO reaction subset. Predictions of ignition delays in shock tubes and species profiles in JSR experiments were also satisfactory. At temperatures above the NTC regime, acetaldehyde ignition and oxidation is affected mainly by the competition between dissociation of CH3CHO and reaction with the radical pool, and by reactions in the methane subset. 相似文献
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Tanh Le Cong 《Proceedings of the Combustion Institute》2009,32(1):427-435
An experimental investigation of the oxidation of hydrogen diluted by nitrogen in presence of CO2 was performed in a fused silica jet-stirred reactor (JSR) over the temperature range 800-1050 K, from fuel-lean to fuel-rich conditions and at atmospheric pressure. The mean residence time was kept constant in the experiments: 120 ms at 1 atm and 250 ms at 10 atm. The effect of variable initial concentrations of hydrogen on the combustion of methane and methane/carbon dioxide mixtures diluted by nitrogen was also experimentally studied. Concentration profiles for O2, H2, H2O, CO, CO2, CH2O, CH4, C2H6, C2H4, and C2H2 were measured by sonic probe sampling followed by chemical analyses (FT-IR, gas chromatography). A detailed chemical kinetic modeling of the present experiments and of the literature data (flame speed and ignition delays) was performed using a recently proposed kinetic scheme showing good agreement between the data and this modeling, and providing further validation of the kinetic model (128 species and 924 reversible reactions). Sensitivity and reaction paths analyses were used to delineate the important reactions influencing the kinetic of oxidation of the fuels in absence and in presence of additives (CO2 and H2). The kinetic reaction scheme proposed helps understanding the inhibiting effect of CO2 on the oxidation of hydrogen and methane and should be useful for gas turbine modeling. 相似文献
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Mohammad Haghighi Zhi-qiang Sun Jin-hu Wu John Bromly Hui Ling Wee Esther Ng Yang Wang Dong-ke Zhang 《Proceedings of the Combustion Institute》2007,31(2):1983-1990
CO2 reforming of methane was studied over a bed of coal char in a fixed bed reactor at temperatures between 1073 and 1223 K and atmospheric pressure with a feed composition of CH4/CO2/N2 in the ratio of 1:1:8. Experimental results showed that the char was an effective catalyst for the production of syngas with a maximum H2/CO ratio of one. It was also found that high H2/CO ratios were favoured by low pressures and moderate to high temperatures. These results are supported by thermodynamic calculations. A mechanism of seven overall reactions was studied and three catalytic reactions of CH4 decomposition, char gasification and the Boudouard reaction was identified as being of major importance. The first reaction produces carbon and H2, the second consumes carbon, and the third (the Boudouard reaction) converts CO2 to CO while consuming carbon. Equilibrium calculations and experimental results showed that any water present reacts to form H2 and carbon oxides in the range of temperatures and pressures studied. Carbon deposition over the char bed is the major cause of deactivation. The rate of carbon formation depends on the kinetic balance between the surface reaction of the adsorbed hydrocarbons with oxygen containing species and the further dissociation of the hydrocarbon. 相似文献
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The degradation of some performances of the drift chambers irradiated with 5 MeV electron beam has been tested. The gas mixtures filled were Ar/CO2, Ar/CH4 and C4H10 in proportion.
The dark current, the pulse height, the energy resolution and the counting rate plateau have been measured during the irradiation. 相似文献
The dark current, the pulse height, the energy resolution and the counting rate plateau have been measured during the irradiation. 相似文献
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以合成包裹体作为腔体,用显微激光拉曼探针就位分析了H2O-CO2-CH4混合流体的高温特性。研究结果表明,在高温下,CH4和CO2相互之间对各自拉曼光谱的影响不大,水分子对它们的拉曼峰有比较大的影响。在等容条件下,流体均一前,随着温度的升高,水分子的氢键几乎呈线性减少,均一为气相的流体,水分子伸缩振动拉曼峰的变化与一般气体变化相似;随着温度升高,体系压力的增加,最大峰频率呈很微小的降低趋势。均一为液相的流体中的水分子,在均一温度时,氢键变化发生了转折,均一后流体中水分子的氢键受温度的影响比均一前明显要小,在测量的最高温度520 ℃,水分子存在着一定的氢键作用。一直到拉曼光谱测量的最高温度580 ℃还未均一的流体,液相中水分子存在比较强的氢键作用。 相似文献
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A DRIFT CHAMBER WITH UNIFORM ELECTRIC FIELD AND MEASUREMENTS OF THE ELECTRON DRIFT VELOCITY 下载免费PDF全文
The measurements of the electron drift velocity as a function of the electric field have been made in a small drift chamber with uniform electric field for Ar/CH4, Ar/i-C4H10, Ar/CO2 and SQS gas mixtures. The values of the electric field range from obout 0.3 to 2.5kV/cm. The results of the measurements are discussed. 相似文献
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Fast reactions between nitromethane and aluminium nanoparticles are studied using transient spectral methods. In comparison with species produced by pure nitromethane, the emergence time for species produced by nitromethane after addition of 1 g of aluminium nanoparticles decreases by 46-58% and the emission intensity increases by 13-100%. The results demonstrate that aluminium nanoparticles have positive effect on accelerating the decomposition rate of nitromethane and that the explosion efficiency of nitromethane is greatly improved. Fast reactions carried out between nitromethane and aluminium nanoparticles in different environments (CO2, H2O and O2) reveal that O2 and an appropriate amount of H2O improve the explosion efficieney of nitrornethane, whereas CO2 has the weakest effect on improving this parameter. The investigations provide insights into the process occurring in actual systems involving propellants and fuel-air explosives. 相似文献