Numerical prediction of pressure drop and flow characteristics of activated carbon and salt-water for flow-electrode capacitive mixing (F-CapMix)

Abstract

In flow-electrode capacitive mixing (F-CapMix), prediction of the flow characteristics and pressure drop of the flow-electrode is important as it pertains to both efficient charge percolation and electron transport of activated carbons in the flow-electrode, as well as the net power of F-CapMix. In this study, the flow characteristics and pressure drop of activated carbon and salt-water within the flow-electrode of F-CapMix are predicted by applying numerical simulations, when the channel depth for the flow-electrode is changed from 0.5 mm to 2.5 mm. The numerical simulation was validated by comparing the experimental results of pressure drop measurements of the flow-electrode. To analyze the variables related to electron transfer between the activated carbon and the current collector, the particle wall normal pressure was numerically calculated. As the channel depth for the flow-electrode decreased by 0.5 mm, the pressure exerted by the activated carbon particle on the wall increased by 32.92 % on average. Consequently, the power density of F-CapMix increased to 14.03 % owing to the elevated pressure at the wall. Predicting the behavior of activated carbon and the pressure drop through numerical simulation is a key step for the designing of the flow channel for the F-CapMix.