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Development and application of the Surface Laser Induced Fluorescence technique.

机译：表面激光诱导荧光技术的发展与应用。

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摘要

The mechanisms that control the mass transfer of gases across the air-water interface are not well understood. Current models for air and water gas transfer have limited effectiveness because they are based on large scale bulk conditions and empirical estimates, yet the mechanisms that control the transfer are small scale. The Surface Laser Induced Fluorescence (SLIF) technique was developed and it provided measurement of small scale variation in mass transfer across the surface of the liquid. The SLIF technique was applied to study the relationship between atmospheric humidity and oxygen mass transfer across the air-water interface.;The Surface Laser Induced Fluorescence technique is based on the premise that variation of surface-imaged fluorescence intensity of a dissolved fluorescent probe corresponds to variation in the oxygen concentration below the surface because the oxygen acts as a quencher of the probe. A tank system was developed to create a known difference in the concentration gradient within the same SLIF image to demonstrate that the SLIF system detects variation in fluorescence related solely to variations in oxygen concentration. Image processing procedures were developed to remove uneven incident radiation. The SLIF system demonstrated large fluorescence intensity differences between water saturated with dissolved oxygen and water with low levels of dissolved oxygen.;The SLIF technique was applied to study oxygen mass transfer across flat air-water interfaces. The SLIF images were transformed into mapped estimates of the relative mass transfer rates and boundary layer thicknesses with high spatial resolution. The Surface Laser Induced Fluorescence technique identified mass transfer variations related to Rayleigh-Benard downwelling within flat air-water interface images and maps.;The effect of relative humidity on mass transfer across flat air-water interfaces was examined using the SLIF technique. It was shown that the relative humidity had an effect upon the presence, size, speed, and relative thickness of Rayleigh-Benard downwelling zones under flat air-water interfaces. It is theorized that Rayleigh-Benard circulations affect the mass transfer of gases across the interface by convective transport of oxygen rich liquid to downwelling zones from the surrounding liquid just below the air-water interface. The transport of oxygen rich liquid from this near-surface zone reduces the resistance to mass transfer across the interface for renewed areas but increases the mass transfer resistance across the downwelling zones.
机译：控制气体通过空气-水界面的质量转移的机制尚未充分了解。当前的空气和水煤气传输模型的有效性有限，因为它们基于大规模的总体条件和经验估计，但是控制传输的机制规模很小。研发了表面激光诱导荧光（SLIF）技术，该技术可测量液体表面传质的小尺度变化。应用SLIF技术研究大气湿度与氧气在空气-水界面上的传质之间的关系。表面激光诱导荧光技术的前提是溶解的荧光探针的表面成像荧光强度的变化对应于表面下氧气浓度的变化，因为氧气起探针的淬灭作用。开发了一个储罐系统，以在同一SLIF图像内在浓度梯度上产生已知差异，以证明SLIF系统检测到的荧光变化仅与氧浓度的变化有关。开发了图像处理程序以消除不均匀的入射辐射。 SLIF系统显示出溶解氧饱和的水和溶解氧水平低的水之间的荧光强度差异很大; SLIF技术用于研究在平坦的空气-水界面上的氧气质量传递。 SLIF图像被转换为​​具有较高空间分辨率的相对传质速率和边界层厚度的映射估计。表面激光诱导荧光技术在平坦的空气-水界面图像和地图中确定了与瑞利-贝纳德下沉有关的传质变化。使用SLIF技术检查了相对湿度对平坦的空气-水界面之间的传质的影响。结果表明，相对湿度对平坦的空气-水界面下的Rayleigh-Benard下降区的存在，大小，速度和相对厚度有影响。从理论上讲，瑞利-贝纳德循环通过将富氧液体从空气-水界面正下方的周围液体对流传输到下流区，影响了气体在界面上的传质。来自该近表面区域的富氧液体的输送降低了对新区域的整个界面上的传质阻力，但增加了向下流区上的传质阻力。

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  • 作者

    Donath, Gregory Wayne.;

  • 作者单位

    Auburn University.;

  • 授予单位 Auburn University.;
  • 学科 Engineering Chemical.;Engineering Marine and Ocean.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 430 p.
  • 总页数 430
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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