Investigation of the chemical kinetics of incomplete oxidation processes in shock tubes

多联产工艺的发展需要对燃料过剩的反应系统中的化学工艺有详细的了解。一方面，关于气相过程和碳烟形成之间的限制条件的信息是必要的，另一方面，为了能够基于模拟开发和优化多联产过程，需要经过验证的反应机理。在第一个资助期，研究了在phi=2时甲烷的部分氧化。使用添加剂加速甲烷的自燃，使发动机能够在多联产条件下运行在自燃模式下。在目前研究的条件下，除CO2和H2O外，主要生成合成气(CO和H2)。在第二个资助期，研究范围扩大到燃料过剩程度更高的混合物，这些混合物能够形成碳-碳键并产生不饱和碳氢化合物。在这里，使用了天然气和新的添加剂(二甲醚和丁二烯)。所测量的点火延迟时间和产品组成是在GM1项目中进一步开发基于FOR1993的机制(PolyMech)的基础。由于添加剂在燃料丰富的条件下占燃料消耗的很大一部分，下一个供资期间将重点放在使用先前确定的实验方法作为添加剂的臭氧上。臭氧的优点是，即使在非常低的浓度下，它也会增加燃料的反应性。另一个优点是，它可以通过臭氧发生器以低成本在线产生。然而，到目前为止，它在富燃料条件下的反应动力学还没有得到充分的研究。作为FOR1993中的验证数据，点火延迟时间、最终产品浓度以及时间分辨的甲烷、臭氧、一氧化碳浓度和温度将在激波管中测量，使用甲烷和天然气作为燃料。在燃料非常丰富的条件下，增加空气的数量会增加燃料消耗，但也会导致更高的末端温度，从而促进碳烟的形成。通过使用含氧添加剂，可以抑制碳烟的形成，因为它们将碳烟形成的低温开始向更高温度移动。在这种情况下，将通过测量碳烟起始时间和碳烟体积分数来研究各种添加剂(如醇或醚)在激波管中的适用性。此外，通过光谱和时间分辨吸收测量对诸如苯和多环芳烃(PAH)等碳烟前体进行时间分辨检测，将有助于确定在添加和不添加添加剂的情况下碳烟形成的限制条件。根据这些结果，将确定条件，在该条件下，可以避免发动机在多联产过程中产生碳烟。

The development of polygeneration processes requires detailed knowledge about chemical processes in reaction systems with a large fuel excess. On one hand, information about the limiting conditions between gas-phase processes and soot formation is necessary, on the other hand, validated reaction mechanisms are required to enable a simulation-based development and optimization of polygeneration processes. In the first funding period, partial oxidation of methane was studied at phi = 2. Additives were used to accelerate the autoignition of methane so that engines can be operated in a self-igniting mode at polygeneration conditions. Under the conditions investigated so far, besides CO2 and H2O, mostly synthesis gas (CO & H2) was formed. In the second funding period, the studies were expanded towards mixtures with even higher fuel excess that enable the formation of carbon-carbon bonds and the generation of unsaturated hydrocarbons. Here, natural gas and new additives (DME and DEE) were used. Measured ignition delay times and product compositions served as basis for further development of the FOR1993-based mechanism (PolyMech) in project GM1.Since the additives account for a significant part of the fuel consumption at fuel-rich conditions, the next funding period will focus on ozone as an additive using the previously established experimental approaches. Ozone has the advantage that it increases the reactivity of the fuel even in very low concentrations. An additional advantage is that it can be generated online at low cost with an ozone generator. Its reaction kinetics in fuel-rich conditions, however are not sufficiently studied so far. As validation data within the FOR1993, ignition delay times, end product concentrations, and time-resolved methane, ozone, carbon monoxide concentrations, and temperatures will be measured in the shock tube using methane and natural gas as fuels.Increasing the amount of air in very fuel-rich conditions increases the fuel consumption, but also leads to higher end temperatures that promote the formation of soot. By using oxygenated additives, soot formation can be suppressed because they shift the low- temperature onset of soot formation towards higher temperatures. In this context, the suitability of various additives such as alcohols or ethers will be investigated in the shock tube by measuring soot inception times and soot volume fractions. In addition, time-resolved detection of soot precursors such as benzene and PAH (polycyclic aromatics) via spectrally- and temporally-resolved absorption measurements will help to determine the limiting conditions for soot formation with and without additives. From these results, conditions will be determined, in which the soot formation in polygeneration processes can be avoided in the engine.