Quantification of the mass transport in a two phase binary system at elevated pressures applying Raman spectroscopy: Pendant liquid solvent drop in a supercritical carbon dioxide environment
Quantification of the mass transport in a two phase binary system at elevated pressures applying Raman spectroscopy: Pendant liquid solvent drop in a supercritical carbon dioxide environment
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应用拉曼光谱对高压下两相二元系统中的质量传递进行量化：超临界二氧化碳环境中的悬垂液体溶剂滴
DOI：
10.1016/j.ijheatmasstransfer.2013.03.046
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发表时间：
2013
影响因子：
5.2
通讯作者：
A. Leipertz
中科院分区：
文献类型：
--
作者：
A. Braeuer;O.S. Knauer;J. Quino;A. Leipertz
本文研究了在低于混合物临界压力（MCP）的压力下，有机溶剂（S）和二氧化碳（CO2）之间的传质。丙酮和二甲基亚砜（DMSO）已被用作有机溶剂。混合物组成的配置文件已被测量通过液体溶剂滴悬垂在稳定的条件下，在加压CO2环境。液滴保持稳定的方法是，通过进料玻璃毛细管将一定量的液体进料到悬垂液滴中，同时从液滴蒸发到CO2环境中。供给到悬滴中的液体是纯有机溶剂或溶解有一些CO2的有机溶剂。应用光学拉曼谱线成像技术对混合物组成的分布进行了定量分析，并对各自涉及的传质机制进行了全面讨论。蒸发冷却被证明是占主导地位的温度变化的内部边缘的下降，而混合水被证明是次要的。通过将质量传递模型拟合到由质量分数组成曲线计算的DMSO浓度曲线，可以导出质量传递性质扩散系数D、Biot-number Bi和质量传递系数β。当丙酮被用作溶剂时，不可能形成稳定的液滴，从而不允许基于模型的质量传递的定量。
Mass transport between organic solvents (S) and carbon dioxide (CO2) has been investigated at pressures below the mixture critical pressure (MCP). Acetone and dimethyl sulfoxide (DMSO) have been used as organic solvents. Profiles of the mixture composition have been measured through liquid solvent drops pendant at steady conditions in a pressurized CO2environment. The drop has been kept steady by feeding exactly that amount of liquid through a feed glass capillary into the pendant drop that evaporated at the same time from the drop into the CO2environment. The liquid fed into the pendant drop has been either pure organic solvent or organic solvent with some CO2dissolved. Profiles of the mixture composition have been quantified applying an optical Raman line imaging technique and the respective involved mass transport mechanisms are discussed comprehensively. Evaporative cooling was shown to dominate the temperature change at the inner margin of the drop, while mixing enthalpies were shown to be of minor importance. By fitting a mass transport model to DMSO concentration profiles, calculated from the mass fraction composition profiles, the mass transport properties diffusivity D, Biot-number Bi and mass transfer coefficient β could be derived. When acetone has been used as solvent, no steady drops could be formed not allowing a model based quantification of the mass transport.