Numerical simulation of reverse electrodialysis with ammonium bicarbonate

A closed-loop reverse electrodialysis (RED) system using thermolytic solution has drawn significant attention in a low-grade waste heat energy recovery. The closed-loop characteristic enable the system have merits such as no need of repetitive pretreatment cost and removal of locational constraint than open-loop RED with sea and river water. In this study, we presents the numerical simulation of RED using ammonium bicarbonate which is one of the promising solute. The permselectivity of ion exchange membrane was calculated from membrane potential with various concentration ratios. We found that the polarization and the power density curve using the computed permselectivity are similar to the experimental results. The RED performance with ammonium bicarbonate was validated according to various concentration combination and flow rate. The open circuit voltage (OCV) and power density fit well for a wide range of solution concentration and the various flow rate. Finally, the optimum value of net power density, which consider the pumping loss, was obtained in terms of the intermembrane distance and the concentration ratio by the net power density contour. Please click Additional Files below to see the full abstract

Power Generation with Thermolytic Reverse Electrodialysis for Low-Grade Waste Heat Recovery

Closed-loop reverse electrodialysis (RED) systems that use a thermolytic solution for low-grade waste heat recovery have attracted significant attention. They have several cost benefits, e.g., the absence of repetitive pretreatment and removal of locational constraints, when compared with open-loop RED systems using seawater and river water. This study presents a model of RED that uses ammonium bicarbonate, and this is a promising solution for closed-loop systems. The modified Planck-Henderson equation is used to calculate the ion exchange membrane potential. The calculation is based on the conductivity measurements as ionization carbonate electrochemical information has not been reported before this study. The solution resistance is experimentally determined. The experimentally obtained permselectivity is implemented into the model to predict the membrane potential more accurately. The results of the improved model are well matched with experimental results under results under various operating conditions of the RED system. In addition, in the model of this study, the net power density was characterized with the consideration of the pumping loss. The improved model predicts a maximum net power density of 0.84 W/m2 with an intermembrane distance of 0.1 mm, a flow rate of 3 mL/min, and a concentration ratio of 200 as optimum conditions. The results of the study are expected to improve our understanding of the ammonium bicarbonate-RED system and contribute to modeling studies using ammonium bicarbonate or certain other compounds for novel technologies of waste heat recovery

Quantification of Vortex Generation Due to Non-Equilibrium Electrokinetics at the Micro/Nanochannel Interface: Particle Tracking Velocimetry

We describe a quantitative study of vortex generation due to non-equilibrium electrokinetics near a micro/nanochannel interface. The microfluidic device is comprised of a microchannel with a set of nanochannels. These perm-selective nanochannels induce flow instability and thereby produce strong vortex generation. We performed tracking visualization of fluorescent microparticles to obtain velocity fields. Particle tracking enables the calculation of an averaged velocity field and the velocity fluctuations. We characterized the effect of applied voltages and electrolyte concentrations on vortex formation. The experimental results show that an increasing voltage or decreasing concentration results in a larger vortex region and a strong velocity fluctuation. We calculate the normalized velocity fluctuation—whose meaning is comparable to turbulent intensity—and we found that it is as high as 0.12. This value is indicative of very efficient mixing, albeit with a small Reynolds number

Transdermal iontophoresis patch with reverse electrodialysis

Reverse electrodialysis (RED) technology generates energy from the salinity gradient by contacting waters with different salinity. Herein, we develop the disposable skin patch using this eco-friendly energy. The current density, which can be controlled easily without special circuit, is enough to iontophoretic drug delivery. In vitro study, this iontophoretic system enhanced the transdermal delivery of peptide, which is difficult to penetrate the skin barrier by simple diffusion. We design the disposable iontophoretic skin patch using RED system and suggest this patch can be apply on new cosmetic patch or disposable drug patch