Cool Pool Diffusion Flames

大多数为陆地、空中和海上运输提供动力的发动机热效率低，并且消耗不可再生燃料。一种新发现的火焰，被称为冷扩散火焰，可以大大提高这些效率——从30%以上提高到60%——并加速可再生燃料的采用。这些火焰还可以提高对野火蔓延和阴燃机制的理解。2012年，在国际空间站上发现了冷却扩散火焰。与传统火焰的2000 K相比，它们的温度异常低，在500 - 1000 K之间。他们的发现已经提高了对点火的理解，但由于所需实验设施的高成本和复杂性，进一步的进展受到阻碍。该项目将通过开发一种以冷焰模式燃烧燃料池的新型设施来降低这一成本。它还将通过进行详细的测量并将其与计算模拟进行比较，提高对冷扩散火焰的理解。该项目的第一个目标是开发新的方法来观察由加热天花板包围的液体燃料池上方的冷却扩散火焰。这将使任何实验室都能以低廉的成本建造这样的设备。将考虑许多液体燃料，包括纯碳氢化合物、传统运输燃料和可再生生物衍生燃料。目前尚不清楚这些燃料中的哪一种可以在空气中以冷扩散火焰的形式燃烧，以及在何种温度和混合馏分下燃烧。也不知道它们是否可以支持稍热的火焰，称为热扩散火焰，以及它们是否可以在没有外部热源的情况下存在。第二个目标将是表征火焰的细节，即火焰的温度，成分，燃烧速率和排放量。第三个目标是使用Cantera软件使用各种化学动力学模型进行自燃模拟，并将预测结果与测量结果进行比较。这些模拟将填补测量中的空白，并有助于评估和开发冷火焰化学模型。该项目的广泛影响包括提高发动机效率，增加可再生燃料的使用，并涉及来自不同背景的研究生和本科生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Most of the engines that power land, air, and sea transportation have low thermal efficiencies and consume nonrenewable fuels. A newly discovered class of flames, called cool diffusion flames, could contribute to dramatic increases in these efficiencies – from upper thirties to sixty per cent – and accelerate the adoption of renewable fuels. These flames could also improve the understanding of wildland fire spread and smoldering mechanisms. Cool diffusion flames were discovered in 2012 aboard the International Space Station. They have unusually low temperatures between 500 – 1000 K, compared to 2000 K for traditional flames. Their discovery has already resulted in an improved understanding of ignition, but further progress has been impeded by the high cost and complexity of the experimental facilities required. This project will reduce this cost by developing a novel facility that burns fuel pools in cool flame mode. It will also improve the understanding of cool diffusion flames by performing detailed measurements and comparing them with computational simulations.The first objective of this project is to develop new ways to observe cool diffusion flames above pools of liquid fuels bounded above by a heated ceiling. This will enable any laboratory to build such a facility inexpensively. Many liquid fuels will be considered, including pure hydrocarbons, traditional transportation fuels, and renewable bio-derived fuels. It is unknown which of these fuels can burn in air as cool diffusion flames, and at what temperatures and mixture fractions. It is also unknown whether they may support slightly hotter flames, called warm diffusion flames, and whether they can exist without an external heat source. The second objective will be to characterize the flame details, namely, the flame temperatures, compositions, burning rates, and emissions. The third objective will be to perform autoignition simulations with Cantera software using various chemical kinetics models and to compare the predictions with the measurements. These simulations will fill gaps in the measurements and help evaluate and develop models of cool flame chemistry. The broader impacts of this project include improving engine efficiency, increasing the use of renewable fuels, and involving graduate students and undergraduates from diverse backgrounds.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.