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首页> 外文期刊>Combustion and Flame >Ozone assisted cool flame combustion of sub-millimeter sized n-alkane droplets at atmospheric and higher pressure
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Ozone assisted cool flame combustion of sub-millimeter sized n-alkane droplets at atmospheric and higher pressure

机译：臭氧在大气压和高压下辅助亚毫米大小正构烷烃液滴的冷焰燃烧

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摘要

Cool flame combustion of individual and isolated sub-millimeter sizedn-heptane (n-C7H16) andn-decane (n-C10H22) droplets are computationally investigated for atmospheric and higher operating pressure (25 atm) conditions with varying levels of ozone (O3) mole fractions in the surroundings. A sphero-symmetric, one-dimensional, transient, droplet combustion model is utilized, employing reduced versions of detailed chemical kinetic models for the fuel species and an appended ozone reaction subset. Comprehensive parametric computations show that the regime of the cool flame burning mode and the transition from cool to hot flames are sensitive to the changes of O3loading, pressure, diluent variation, the strength of initiation source, and the influence of fuel vapor pressure at the ambient condition. For both fuels and over a range of O3concentrations in the ambient, sustained cool flame burning can be directly produced, even for sub-millimeter sized droplets. Over some range of O3concentrations, operating pressure, and drop diameter, a self-sustaining, continuous cool flame burn can be produced without incurring a hot flame transition. For sufficiently high O3concentrations, combustion initiation is always followed by a hot flame transition. Fuel volatility is also shown to be important for initiation and transition to cool flame and hot flame initiation. For fuels having a flash point lower than the ambient temperature (e.g.n-heptane), atomic O radicals formed by O3decomposition react with the partially premixed, flammable gas phase near the droplet surface, leading to OH radicals, water production, and heat that auto-thermally accelerates the combustion initiation process. For fuels with flashpoints higher than the ambient temperature (e.g.n-decane), the reaction progress is limited by the local fuel vapor concentration and the necessity to heat the droplet surface to sufficiently high temperatures to produce locally flammable conditions. As a result, the initial transient for establishing either cool flame or hot flame transition is significantly longer for high flash point fuels. The transition of locally partially premixed reaction to diffusive burning conditions is more evident for high flash point conditions.
机译：在大气和更高工作压力（25 atm）条件下，随着臭氧（O3）摩尔浓度的变化，对单个和隔离的亚毫米大小的正庚烷（n-C7H16）和正癸烷（n-C10H22）小滴的冷火焰燃烧进行了计算研究周围的环境。利用了球对称的一维瞬态液滴燃烧模型，对燃料种类和附加的臭氧反应子集采用简化的详细化学动力学模型。全面的参数计算表明，冷火焰燃烧模式的状态以及从冷火焰到热火焰的过渡对O3负荷的变化，压力，稀释剂变化，引发源的强度以及周围环境中燃料蒸气压的影响均敏感。健康）状况。对于燃料和环境中超过一定范围的O3浓度，即使对于亚毫米大小的液滴，也可以直接产生持续的冷火焰燃烧。在一定范围的O3浓度，工作压力和液滴直径范围内，可以产生自持的，连续的冷火焰燃烧，而不会引起热火焰过渡。对于足够高的O3浓度，始终在燃烧开始之后进行热火焰过渡。燃料挥发性也被证明对于引发和过渡到冷火焰和热火焰引发很重要。对于闪点低于环境温度的燃料（例如，庚烷），由O3分解形成的原子O自由基与液滴表面附近的部分预混合易燃气相反应，导致OH自由基，水产生和自动产生的热量。热加速燃烧的起始过程。对于具有高于环境温度的闪点的燃料（例如正癸烷），反应进程受局部燃料蒸气浓度和将液滴表面加热至足够高的温度以产生局部可燃条件的限制。结果，对于高闪点燃料，用于建立冷火焰或热火焰过渡的初始过渡明显更长。对于高闪点条件，局部部分预混合反应向扩散燃烧条件的转变更为明显。

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  • 来源
    《Combustion and Flame》 |2018年第9期|220-231|共12页
  • 作者

    Fahd E. Alam; Sang Hee Won; Frederick L. Dryer; Tanvir I. Farouk;

  • 作者单位

    Department of Mechanical Engineering, University of South Carolina;

    Department of Mechanical Engineering, University of South Carolina;

    Department of Mechanical Engineering, University of South Carolina,Department of Mechanical and Aerospace Engineering, Princeton University;

    Department of Mechanical Engineering, University of South Carolina;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    n-Alkane; Cool flame; Droplet combustion; Ozone; Flashpoint temperature;

    机译：正构烷烃;凉爽的火焰;小滴燃烧;臭氧;闪点温度;

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