Electrochimica Acta 79 (2012) 57–66 Contents lists available at SciVerse ScienceDirect Electrochimica Acta jou rn al hom epa ge: www.elsevier.com/locate/electacta Numerical simulation of flow electrolysers: Effect of obstacles Pragati Shukla a,d , K.K. Singh b,∗ , P.K. Tewari c,d , P.K. Gupta a a Alkali Metal Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India b Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India c Desalination Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India d Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India a r t i c l e i n f o Article history: Received 7 March 2012 Received in revised form 15 June 2012 Accepted 15 June 2012 Available online 23 June 2012 Keywords: Nernst–Planck Electrolyser Electroneutral bulk Current density a b s t r a c t This study aims at understanding the role the velocity profile can play in affecting the performance of the electorneutral bulk of a continuous flow electrolyser. Numerical simulations have been carried out by solving Navier–Stokes (NS) equations together with the Nernst–Planck (NP) equations. Performance of different geometries in which velocity profile has been altered by putting different types of obstacles has been evaluated. Performance of electrolysers having moving cathode has also been evaluated. Role played by inlet channel has also been investigated. The results obtained for different geometries suggest that it is possible to enhance the performance of the electroneutral bulk by putting obstacles in the flow path but this enhancement may not be very significant. An electrolyser with the cathode moving co-currently with the electrolyte is found to perform better than an electrolyser with cathode moving counter-currently with the electrolyte. Performance of an electrolyser with the inlet channel is found to be better than an electrolyser without inlet channel. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Flow electrolyser finds several applications in industry. They are used for production of metals and synthesis of chemicals such as sodium chlorate, potassium chlorate and sodium hydroxide. They are used to produce gases like chlorine for industrial appli- cations and oxygen for spacecraft and submarines. They can be used for production of hydrogen as source of electrical energy. Cleaning and preservation of old artifacts, electrolytic refining of metals, electrolytic winning of metals, alkaline water electrolysis, anodization, electrometallurgy, electroplating, electrolytic etching of metal surfaces are other industrial applications of flow elec- trolysers. Several studies on flow electrolysers have been reported in literature. Jansson [1] studied flow field in a rotating elec- trolyser. Sioda [2,3] studied electric potential distribution within porous electrodes in flow electrolysers. Blaedel and Wang [4] stud- ied flow-through electrolysers having an electrode composed of reticulated vitreous carbon disks. There are experimental stud- ies aimed at finding mass transfer coefficients or correlations for Sherwood number for flow electrolysers [5–11]. Byrne et al. [12] carried out numerical simulation for a chlorate cell. Qian et al. [13] solved Navier–Stokes and Nernst–Planck equations for simulat- ing an electrochemical reactor having redox electrolyte. Ipek [14] reported numerical simulation for electrolytic pickling of stainless ∗ Corresponding author. E-mail address: kksingh@barc.gov.in (K.K. Singh). steel. Lu et al. [15] developed a steady state numerical model for multi ion parallel electrodes to investigate the concentration and electric distribution in the process of salt water electrolysis under forced convection. Navier–Stokes and Nernst–Planck equations were solved using finite element technique. Effects of inlet velocity and the electrode current on the concentration distribution were investigated. Borg et al. [16] have performed numerical studies for spatial evolution of the ionic concentration of an electrolyte in an isothermal electrochemical cell having a porous separator between electrodes. Kawai et al. [17] carried out numerical simulation of electrolyte flow in a CuSO 4 aqueous electrolyte solution acidi- fied with an excess amount of H 2 SO 4 . Qin and Bau [18] reported coupled solutions of Nernst–Planck, Navier–Stokes and Maxwell’s equations to simulate the MHD (magneto hydrodynamic) flow. Though there have been several studies on flow electrolysers, the effect of flow patterns on the performance of an electrolyser, has not been reported so far. The flux of an ionic species in an electrol- yser consists of three components: electrophoretic flux, convective flux, diffusive flux. In principle, the flux will be a function of veloc- ity field and hence the velocity field should affect the performance of an electrolyser. The objective of this work is to numerically investigate whether the performance of the electroneutral bulk of an electrolyser can be improved by altering the velocity field by putting some obstacles in the flow path of an electrolyte. Compu- tational approach used in the simulations has been validated with the results reported in an earlier study [15]. It may be noted that this study concerns only the electroneutral bulk of the electrolyser. 0013-4686/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2012.06.047