Experimental study of a bimolecular reaction in Poiseuille Flow
Experimental study of a bimolecular reaction in Poiseuille Flow
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DOI：
10.1029/98wr01649
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发表时间：
1998-08
影响因子：
5.4
通讯作者：
V. Kapoor;C. Jafvert;D. Lyn
中科院分区：
文献类型：
--
作者：
V. Kapoor;C. Jafvert;D. Lyn
本文用分光光度计对层流中的双分子化学反应（反应物1+反应物2 →产物）进行了实验观察。反应速率（rm）遵循二级速率定律;即，rm = к C1 C2，其中cm（m=1，2）是反应物浓度。通过使用停流技术在完全混合的间歇式反应器中监测反应动力学来独立地估计反应速率常数K。在反应输运实验中，反应物被引入管中，并且最初由尖锐的界面分离。流体速度在管道横截面上的变化导致反应物的浓度围绕其横截面平均值（c <$m）变化。浓度（c′m）的这些空间变化影响总反应速率。横截面平均反应速率由下式给出，其中是偏析强度。实验观察到的突破浓度的产品是在协议的数值模型，占偏析强度的影响。忽略偏析强度的影响，预测的产品浓度大大超过实验观察。这表明，对于最初不重叠的反应物，偏析强度为负（s < 0），流动系统中的总化学转化速率可能与用平均浓度代替反应速率所暗示的显著不同。
A bimolecular chemical reaction (reactantl + reactant2 → products) in laminar Poiseuille flow is experimentally observed using a spectrophotometer. The reaction rate (rm) follows the second‐order rate law; that is, rm = кC1C2, where cm(m=1, 2) are the reactant concentrations. The reaction rate constant к is independently estimated by monitoring the reaction kinetics in a completely mixed batch reactor using the stopped‐flow technique. In the reactive transport experiments, the reactants are introduced in a tube and are initially separated by a sharp interface. The variation of the fluid velocity over the cross section of the tube causes the concentrations of the reactants to vary around their cross‐sectional average values (c¯m). These spatial variations in the concentrations (c′m) influence the overall reaction rate. The cross‐sectional average reaction rate is given by , where is the segregation intensity. The experimentally observed breakthrough concentration of the product is in agreement with a numerical model that accounts for the effects of the segregation intensity. On ignoring the influence of the segregation intensity, the predicted product concentration substantially exceeds the experimental observations. This shows that for initially non‐overlapping reactants the segregation intensity is negative (s < 0) and that the overall chemical transformation rate in flowing systems can be significantly different from that implied by substituting the mean concentrations in the expression for the reaction rate.