Purification of Bioethanol Using Microbubbles Generated by Fluidic Oscillation: A Dynamical Evaporation Model
Purification of Bioethanol Using Microbubbles Generated by Fluidic Oscillation: A Dynamical Evaporation Model
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DOI：
10.1021/acs.iecr.6b01666
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发表时间：
2016-12-21
影响因子：
4.2
通讯作者：
Zimmerman, William B.
中科院分区：
文献类型：
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作者：
Abdulrazzaq, Nada N.;Al-Sabbagh, Baseem H.;Zimmerman, William B.
开发了浸入乙醇-水混合物液体中的单个气体微泡的计算模型并进行了数值求解。这补充了早期的二元蒸馏实验，其中乙醇-水混合物被热空气微泡汽提，达到约 98% vol。从共沸混合物中提取乙醇。所提出的模型是使用伽辽金有限元方法开发的，以预测气体微泡的温度和蒸汽含量作为其在液相中的停留时间的函数。该模型采用了一种新颖的速率定律，该定律在与 10(-3)s 微泡内部混合相关的时间尺度上演化。单个气泡的模型预测与现有的实验数据非常一致，表明微泡状态中乙醇与水的比率高于预期比率，这与所有初始气泡温度和所考虑的所有液体乙醇摩尔分数以及在适合薄液体层的非常短的接触时间内的平衡理论一致。我们之前的实验表明，随着气泡槽内液体深度的减小，液体温度降低；随着液体深度的减小，出口气体温度升高；随着液体混合物深度的减小和空气微泡温度的升高，乙醇的汽提效率提高，所有这些都与计算模型的预测一致。
A computational model of a single gas microbubble immersed in a liquid of ethanol-water mixture is developed and solved numerically. This complements earlier binary distillation experiments in which the ethanol-water mixture is stripped by hot air microbubbles achieving around 98% vol. ethanol from the azeotropic mixture. The proposed model has been developed using Galerkin finite element methods to predict the temperature and vapor content of the gas microbubble as a function of its, residence time in the liquid phase. This model incorporates a-novel rate law that evolves on a time scale related to the internal mixing of microbubbles of 10(-3)s. The model predictions of a single bubble were shown to be in very good agreement with the existing experimental:data, demonstrating, that the ratio of ethanol:to water in the microbubble regime are higher than the expected ratios that would be consistent with equilibrium theory for all initial bubble temperatures and all liquid ethanol mole fractions considered and within the very short contact times appropriate for thin liquid layers. Our previous experiments showed a decrease in the liquid temperature with decreasing liquid depth in the bubble tank, an increase in the outlet gas temperature with decreasing liquid depth, and an improvement in the stripping efficiency of ethanol upon decreasing the depth of the liquid mixture and increasing the temperature of the air microbubbles, all of which are consistent with the predictions of the computational model.