Mass-transfer characterization in a parallel-plate electrochemical reactor with convergent flow

• Published in: Electrochimica acta 2013-12, Vol.113, p.575-582
• Main Authors: Colli, A.N., Bisang, J.M.
• Format: Article
• Language: English
• Subjects: Computational fluid dynamics; Convergent flow; Cross sections; Current distribution; Fluid flow; Laminar flow; Mass-transfer coefficient; Mathematical models; Parallel-plate electrodes; Reactors; Reduction; Reynolds number
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2013.10.005

•A convergent laminar flow enhances and becomes more uniform the mass-transfer rate.•The mass-transfer rate is increased under convergent turbulent flow conditions.•The mass-transfer rate under convergent laminar flow can be theoretically predicted.•A convergent duct improves the reactor behaviour and the concept is easily applicable. A continuous reduction in the cross-section area is analysed as a means of improving mass-transfer in a parallel-plate electrochemical reactor. Experimental local mass-transfer coefficients along the electrode length are reported for different values of the convergent ratio and Reynolds numbers, using the reduction of ferricyanide as a test reaction. The Reynolds numbers evaluated at the reactor inlet range from 85 to 4600 with interelectrode gaps of 2 and 4mm. The convergent flow improves the mean mass-transfer coefficient by 10–60% and mass-transfer distribution under laminar flow conditions becomes more uniform. The experimental data under laminar flow conditions are compared with theoretical calculations obtained by a computational fluid dynamics software and also with an analytical simplified model. A suitable agreement is observed between both theoretical treatments and with the experimental results. The pressure drop across the reactor is reported and compared with theoretical predictions.