Rational design of turbulence promoters in electrochemical reactors using numerical simulations of periodic sections

Abstract

This study presents a validated model for predicting fully developed incompressible flow in both laminar and turbulent conditions, with mass-transfer under limiting current conditions, in electrochemical reactors with periodic sections. The model significantly reduces computational costs and enables more efficient simulations. For the turbulent case, a more rigorous convection-diffusion equation is developed, and a new compact equation valid for periodic sections is proposed to replace the previously defined one, after identifying an unnecessary term. Various turbulence promoters, including cylindrical, rhomboidal, rectangular, spherical or octahedral shapes and expanded meshes, were evaluated to determine the most effective for enhancing the global mass-transfer coefficient or reducing the mass-transfer distribution. From the point of view of the global mass-transfer coefficient the best situation is achieved with a rhomboidal geometry, but the first three promoters just cited show a similar distribution of the local value. The study also concludes that certain turbulence promoter designs, such as square, oval, or cylindrical structures, produces a high-pressure drops, while others, like two displaced rhombuses or expanded metal, present a lower-pressure drops. Therefore, the selection of a turbulence promoter should be based on a balance between mass-transfer efficiency and economic considerations specific to each industrial process.