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

1142312 cernansky采用低温燃烧（LTC）的新型发动机设计已被确定为降低排放、提高效率的关键，从而减少了美国对外国燃料来源的依赖。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是由氢过氧自由基（HO2）和烷基过氧自由基（RO2）控制的，但这些物种不容易在发动机和其他燃烧系统中用现有的方法测量。这些自由基的定量测量和LTC化学模型的发展将大大缩短LTC效益实现的时间。该计划的重点是证明腔增强磁光旋转（CEMOR），一种由德雷塞尔大学开发的高灵敏度和选择性激光诊断技术，可以应用于反应体系中HO2和RO2的原位测量。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质的选择性检测。在我们的实验室中，我们已经证明，CEMOR可以选择性地观察顺磁性物质，简化了在其他复杂混合物中的检测，我们还首次使用MOR和CEMOR在稀薄的预混甲烷/空气火焰中测量自由基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比MOR灵敏度的增加。下一步是使用CRDS和CEMOR在光解电池的受控环境中测量HO2，以生成高分辨率的吸收截面数据，并校准CEMOR技术，以用于随后在燃烧环境中进行定量测量的演示。将CEMOR应用于HO2和RO2自由基的原位测量将为低、中温燃烧系统的反应动力学提供新的见解。这将有助于下一代发动机系统的设计，使用这种反应机制，以实现提高效率和减少排放。这种新的测量能力也将在其他需要高灵敏度和选择性过氧自由基测量的领域（例如，大气化学）中发挥作用。采用低温燃烧技术的发动机设计的转变对社会的影响可能是巨大的，而这项研究将为实现这种转变提供一个重要的工具。因此，这项研究是适当的，也是必要的。该研究的教育影响将通过为学生提供在光学诊断和燃烧科学方面的培训机会，为他们提供为燃烧/能源社区做出贡献所需的技能。该项目将支持一名研究生研究助理，并期望一到两名本科生参与该项目，作为我们荣誉研究计划经验的一部分。在德雷塞尔大学现有成功项目的基础上，将特别关注吸引代表性不足的少数民族和女性学生。研究结果将以专业报告、档案出版物、网站条目和论文的形式呈现，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.