Fluorometric Measurement and Modeling of Droplet Temperature Changes in an Electrospray Plume
Fluorometric Measurement and Modeling of Droplet Temperature Changes in an Electrospray Plume
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DOI：
10.1021/ac402364g
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发表时间：
2014-01-07
影响因子：
7.4
通讯作者：
Cook, Kelsey D.
中科院分区：
文献类型：
--
作者：
Gibson, Stephen C.;Feigerle, Charles S.;Cook, Kelsey D.
用比例荧光法测量了电喷雾羽流中液滴温度的变化。在典型的操作条件下，液滴温度沿喷雾轴在前5.0 mm内下降约30 K，随后轻微（类似于2-3 K）再升温。采用扩散控制和表面控制蒸发模型拟合实验轴向分布（z轴）。两种模型都能很好地拟合喷雾冷却部分的实验数据（Pearson相关系数R >= 0.994），但表面控制模型需要不切实际的液滴半径值才能获得良好的拟合。在靠近发射器尖端的给定Z的横向剖面中，外围的温度比喷雾轴的温度低（3.0-10 K）。这一行为与预期的小液滴对喷雾外围的富集一致。在较长的轴向距离，横向剖面相对平坦。当液体流速较低时，液滴温度作为轴向位移的函数下降得更快，这可能是由于液滴尺寸和/或速度随流速的变化而变化。
The evolution of droplet temperatures in an electrospray plume was measured via ratiometric fluorescence. Under typical operating conditions, droplet temperatures decrease similar to 30 K over the first 5.0 mm along the spray axis, followed by a slight (similar to 2-3 K) rewarming. Experimental axial profiles (Z-axis) were fit by use of diffusion-controlled and surface-controlled evaporation models. Both models fit the experimental data well for the cooling portion of the spray (Pearson correlation coefficient R >= 0.994), but the surface-controlled model required unrealistic droplet radius values to obtain a good fit. In lateral profiles at a given Z near the emitter tip, temperatures are lower (by 3.0-10 K) in the periphery than on the spray axis. This behavior is consistent with the expected enrichment of the spray periphery with smaller droplets. At longer axial distances, lateral profiles were relatively flat. Droplet temperature as a function of axial displacement fell more rapidly at lower liquid flow rates, possibly attributable to changes in droplet size and/or velocity with flow rate.