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Autoignition dynamics of DME/air and EtOH/air homogeneous mixtures

机译：DME /空气和EtOH /空气均匀混合物的自燃动力学

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The autoignition kinetics of DME/air and EtOH/air stoichiometric mixtures are compared with the use of algorithmic tools from the CSP method at a range of initial conditions that refers to the operation of reciprocating engines. DME and EtOH are two isomer fuels, with the potential for production from renewable sources, that have virtually identical thermochemistry; i.e. very closely equal heat of combustion and adiabatic flame temperature. These isomer fuels have drastically different ignition delays because of their different kinetics. In particular, the first and largest part of the ignition delay in the DME and EtOH cases is dominated by two different sets of components of carbon chemistry, while the last and shortest part is dominated by the same hydrogen chemistry. Considering sufficiently large initial temperatures, in the DME case the time scale that characterizes autoignition in the first part is promoted by single-carbon chemistry and is opposed mainly by recombination of CH3 radicals. On the contrary, in the EtOH case the two-carbon chain retains its bond in that part. Therefore, the hydrogen chemistry plays an important role in promoting the generation of the time scale that characterizes autoignition from the start of the process, while the reactions that oppose the generation of this time scale involve HO2 and H2O2 and they are not as effective as the reactions opposing ignition for DME. These features generate a substantially shorter ignition delay for EtOH. This situation is reversed for sufficiently low initial temperatures due to the shift in relative importance between internal and external H-abstraction that occurs as temperature increases. (C) 2015 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
机译：将DME /空气和EtOH /空气化学计量混合物的自燃动力学与CSP方法的算法工具在一系列涉及往复式发动机运行的初始条件下的使用进行了比较。 DME和EtOH是两种异构燃料，具有可再生能源生产的潜力，它们的化学性质基本相同。即非常接近相等的燃烧热和绝热火焰温度。这些异构燃料由于动力学不同，点火延迟大不相同。特别是，在DME和EtOH情况下，点火延迟的第一和最大部分由两组不同的碳化学成分控制，而最后和最短部分则由相同的氢化学控制。考虑到足够大的初始温度，在DME情况下，表征第一部分自燃的时间尺度是由单碳化学促进的，而主要是由CH3自由基的重组所阻碍。相反，在EtOH情况下，二碳链在该部分保留其键。因此，氢化学在从过程开始时就促进以自燃为特征的时间尺度的产生中起着重要作用，而反对这一时间尺度产生的反应涉及HO2和H2O2，它们不如氢氧根和氢氧根有效。与DME着火相反的反应。这些特征为EtOH产生了明显较短的点火延迟。对于初始温度足够低的情况，由于随着温度升高而发生的内部和外部H吸收之间的相对重要性发生了变化，这种情况发生了逆转。 （C）2015年燃烧研究所。由Elsevier Inc.出版。保留所有权利。

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