Methane And Dimethyl Ether Oxidation At Elevated Temperatures And Pressure
Methane And Dimethyl Ether Oxidation At Elevated Temperatures And Pressure
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发表时间：
2008
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通讯作者：
C. Zinner
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作者：
C. Zinner
在高温高压下，在激波管中研究了两种甲烷 (CH4) 和二甲醚 (CH3OCH3 或 DME) 混合物在空气中的自燃和氧化。这些实验是在反射激波区域进行的，压力范围为 0.8 至 35.7 个大气压，温度范围为 913 至 1650 K，当量比为 2.0、1.0、0.5 和 0.3。点火延迟时间是从体积比分别为 80/20% 和 60/40% 的 CH4/CH3OCH3 燃料混合物的激波管端壁压力迹线获得的。对数据的仔细检查表明，混合物的能量释放发生在入射冲击波到达和点火事件之间的时间内。设计了温度和压力的调节方案来考虑这种能量释放及其对混合物点火的影响。针对这些压力和温度调整数据开发了两个单独的点火延迟相关性。这些相关性根据已知的温度、压力和甲烷、二甲醚和空气的物质摩尔分数 (0.21 O2 + 0.79 N2) 估算点火延迟。第一个相关性是针对在温度大于或等于 1175 K 和压力范围从 0.8 到 35.3 atm 时发生的点火延迟而开发的。第二个相关性是针对在低于或等于 1175 K 的温度和 18.5 至 40.0 atm 的压力范围内发生的点火延迟而开发的。发现这两种相关性和这些实验的数据之间总体上存在良好的一致性。这些实验的结果还包括，在压力等于或低于 10 个大气压的情况下，二甲醚浓度的增加将持续产生更快的点火时间。在大于十个大气压的压力下，富含燃料的混合物与较低浓度的二甲醚可以提供最快的点火时间。
Autoignition and oxidation of two Methane (CH4) and Dimethyl Ether (CH3OCH3 or DME) mixtures in air were studied in shock tubes over a wide range of equivalence ratios at elevated temperatures and pressures. These experiments were conducted in the reflected shock region with pressures ranging from 0.8 to 35.7 atmospheres, temperatures ranging from 913 to 1650 K, and equivalence ratios of 2.0, 1.0, 0.5, and 0.3. Ignition delay times were obtained from shock-tube endwall pressure traces for fuel mixtures of CH4/CH3OCH3 in ratios of 80/20 percent volume and 60/40 percent volume, respectively. Close examination of the data revealed that energy release from the mixture is occurring in the time between the arrival of the incident shock wave and the ignition event. An adjustment scheme for temperature and pressure was devised to account for this energy release and its effect on the ignition of the mixture. Two separate ignition delay correlations were developed for these pressureand temperature-adjusted data. These correlations estimate ignition delay from known temperature, pressure, and species mole fractions of methane, dimethyl ether, and air (0.21 O2 + 0.79 N2). The first correlation was developed for ignition delay occurring at temperatures greater than or equal to1175 K and pressures ranging from 0.8 to 35.3 atm. The second correlation was developed for ignition delay occurring at temperatures less than or equal to1175 K and pressures ranging from 18.5 to 40.0 atm. Overall good agreement was found to exist between the two correlations and the data of these experiments. Findings of these experiments also include that with pressures at or below ten atm, increased concentrations of dimethyl ether will consistently produce faster ignition times. At pressures greater than ten atmospheres it is possible for fuel rich mixtures with lower concentrations of dimethyl ether to give the fastest ignition times.