Electrokinetic energy conversion of high pressure-driven flow with pressure-viscosity effect at high zeta potential

Abstract

In this study, the electrokinetic energy conversion efficiency is investigated theoretically in high pressure-driven flow with the pressure-viscosity effect. Calculations of the electrokinetic flow in a straight nanochannel are based on the Poisson-Boltzmann equation and modified fluid momentum equation. Once the viscosity of fluid is dependent on the pressure, the strongly non-linear governing equation should be solved simultaneously due to the unknown fluid viscosity. Thus, the domain perturbation method is used to solve the distributions of flow velocity and pressure. Based on obtained velocity and pressure, the maximum conversion efficiency is calculated by thermodynamic analysis. Results show the maximum efficiency increases with the decrease of salt concentration and the peak efficiency can be obtained at sufficiently low salt concentration. For a given salt concentration, the maximum efficiency decreases monotonously with the increase of pressure-viscosity coefficient. Besides, the maximum energy conversion efficiency of ignoring the pressure-viscosity effect is larger than that of considering the pressure-viscosity effect.