Effect of channel size on mass transfer during liquid-liquid plug flow in small scale extractors
Effect of channel size on mass transfer during liquid-liquid plug flow in small scale extractors
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DOI：
10.1016/j.cej.2014.10.012
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发表时间：
2015-02-15
影响因子：
15.1
通讯作者：
Angeli, Panagiota
中科院分区：
文献类型：
--
作者：
Tsaoulidis, Dimitrios;Angeli, Panagiota
本文研究了管道尺寸对内径0.5 ~ 2mm的毛细管液-液塞流传质特性的影响。研究了在不同停留时间、分散相分数和混合速度下，硝酸溶液中{UO2}（2+）离子萃取成与乏核燃料后处理相关的TBP/IL混合物。随着通道尺寸的减小，萃取效率提高。对于给定的通道长度和所有通道尺寸，混合物速度的增加会降低萃取效率。各通道的总传质系数（k(L)alpha）在0.049 ~ 0.29 s（-1）之间变化，随通道尺寸的增大而减小。k(L) α沿提取通道的演化在各通道尺度下均呈减小趋势。将实验得到的传质系数与文献中已有的液-液和气-液分段流模型进行了比较。结果与液-液体系的经验相关关系吻合较好。建立了一个有限元模型，求解了两个阶段通道内的速度场和浓度场，该模型考虑了在进口和出口具有周期性边界条件的单元槽（一个塞和一个段塞）。该模型利用塞流几何特性的实验数据，较好地预测了实验测量的萃取效率（平均相对误差为11%）。(C) 2014年作者。Elsevier B.V.出版
In this paper the effect of channel size on the mass transfer characteristics of liquid-liquid plug flow was investigated for capillaries with internal diameter ranging from 0.5 to 2 mm. The extraction of {UO2}(2+) ions from nitric acid solutions into TBP/IL mixtures, relevant to spent nuclear fuel reprocessing, was studied for different residence times, dispersed phase fractions, and mixture velocities. It was found that extraction efficiencies increased as the channel size decreased. For a given channel length and for all channel sizes, an increase in mixture velocity decreased the extraction efficiency. The overall mass transfer coefficients (k(L)alpha) for all channels varied between 0.049 and 0.29 s(-1) and decreased as the channel size increased. The evolution of the k(L)alpha along the extraction channel showed a decreasing trend for all the channel sizes. The experimentally obtained mass transfer coefficients were compared with existing models for liquid-liquid and gas-liquid segmented flows from the literature. The results showed good agreement with the empirical correlation proposed for a liquid-liquid system. A finite element model was developed that solved the velocity and concentration fields in the channel for both phases considering a unit cell (one plug and one slug) with periodic boundary conditions at the inlet and the outlet. The model used experimental data for the geometric characteristics of the plug flow and predicted reasonably well the experimentally measured extraction efficiencies (with mean relative error of 11%). (C) 2014 The Authors. Published by Elsevier B.V.