EAGER/CEMOR: A New Diagnostic for Quantitative Measurement of HO2 and RO2

1142312 Cernansky实施利用低温燃烧(LTC)运行的新发动机设计已被确定为减少排放、提高效率并从而减少美国对外国燃料来源的依赖的关键。不幸的是，描述LTC的化学模型不足以进行这些设计，虽然最好的理论表明LTC受氢过氧基(HO2)和烷基过氧基(RO2)控制，但这些物种在发动机和其他燃烧系统中不容易用现有方法测量。这些自由基的定量测量和LTC化学模型的发展将极大地缩短实现LTC益处的时间。这项计划的重点是演示腔增强磁光旋转(CEMOR)，这是一种高灵敏度和选择性的激光诊断技术，可用于在线测量反应体系中的HO2和RO2。CEMOR结合了腔衰荡光谱(CRDS)的灵敏度和磁光旋转(MOR)的选择性，在复杂的反应环境中提供了对弱吸收物种的选择性检测。我们的实验室已经证明，CEMOR允许选择性地观察顺磁物种，简化了在其他复杂混合物中的检测，我们还使用MOR和CEMOR首次测量了稀薄预混甲烷/空气火焰中的自由基OH。这些结果证明了使用MOR和CEMOR技术测量燃烧产生的自由基的有效性，并说明了CEMOR技术比MOR技术具有更高的灵敏度。下一步是使用CRDS和CEMOR测量光解池受控环境中的HO2，以便产生高分辨率的吸收截面数据，并校准CEMOR技术，以便随后在燃烧环境中进行定量测量。CEMOR用于原位测量HO2和RO2自由基的智能价值将为研究中低温燃烧系统的反应动力学提供新的视角。这将有助于设计下一代发动机系统，使用这种反应机制来实现更高的效率和更低的排放。这种新的测量能力也将在需要高灵敏度和选择性的过氧基测量的其他领域(例如大气化学)有用。更广泛的影响向采用低温燃烧技术的发动机设计过渡的社会影响可能是巨大的，这项研究将提供一个重要的工具来帮助实现这种过渡。因此，这项研究既是适当的，也是必要的。这项研究的教育影响将是通过提供一个机会，培训学生在光学诊断和燃烧科学，使他们所需的技能，为燃烧/能源社区作出贡献。一个研究生研究助理将得到这个项目的支持，一个或两个本科生将参与这个项目，作为我们荣誉研究计划经验的一部分。在德雷克塞尔大学现有成功项目的基础上，将特别注意吸引代表性不足的少数族裔和女性学生。研究结果将以专业报告、档案出版物、网站条目和论文/学位论文的形式公布，为其他研究人员和公众提供了解新的重要燃烧过程所需的信息。

1142312 CernanskyImplementing new engine designs that operate utilizing Low Temperature Combustion (LTC) has been identified as key to lowering emissions, enhancing efficiency and thereby reducing the dependency of the United States on foreign sources of fuel. Unfortunately, the chemistry models describing LTC are inadequate to proceed with these designs and, while the best theories suggest that LTC is controlled by hydroperoxy radical (HO2) and alkylperoxy radical (RO2), these species are not readily measured in engines and other combustion systems by existing methodologies. Quantitative measurement of these radicals and development of LTC chemistry models will significantly shorten the time to implement the benefits of LTC. This program is focused on demonstrating that cavity enhanced magneto-optical rotation (CEMOR), a highly sensitive and selective laser diagnostic technique developed at Drexel University, can be applied for in situ measurement of HO2 and RO2 in reaction systems. CEMOR combines the sensitivity of cavity ringdown spectroscopy (CRDS) with the selectivity of magneto optic rotation (MOR) to provide selective detection of weakly absorbing species in complex reacting environments. We have shown in our laboratory that CEMOR allows selective observation of paramagnetic species, simplifying detection in otherwise complicated mixtures, and we also have made the first measurements of a radical, OH, in a lean premixed methane/air flame using MOR and CEMOR. These results demonstrate the effectiveness of measuring combustion generated radicals using the MOR and CEMOR techniques, and illustrates the increase in sensitivity CEMOR exhibits over MOR. The next step is to measure HO2 in the controlled environment of a photolysis cell using both CRDS and CEMOR in order to generate high resolution absorption cross section data and to calibrate the CEMOR technique for the subsequent demonstration of quantitative measurements in a combustion environment. Intellectual Merit Application of CEMOR for in situ measurements of HO2 and RO2 radicals will provide new insight into the reaction dynamics of low and intermediate temperature combustion systems. This will aid in the design of the next generation engine systems that use this reaction regime to achieve increased efficiency and reduced emissions. This new measurement capability also will be useful in other areas (e.g., atmospheric chemistry) where highly sensitive and selective peroxy radical measurements are desired. Broader Impact The societal impact of transitioning to engine designs employing low temperature combustion technologies could be enormous, and this research will provide an important tool to help enable such a transition. As such, the research is both appropriate and needed. The educational impact of the research will be through providing an opportunity to train students in optical diagnostics and combustion science, giving them the required skills to contribute to the combustion/energy community. One graduate research assistant will be supported by this project, and one or two undergraduate students are expected to participate in this project as part of our Honors Research Program experience. Special attention will be given to attracting underrepresented minority and female students building on successful programs existing at Drexel University. The results of the research will be presented as professional presentations, archival publications, website entries, and theses/dissertations, providing other researchers and the public with the information needed to understand newly important combustion processes.