Effects of fluid slippage on pressure‐driven electrokinetic energy conversion in conical nanochannels

Abstract

The effects of fluid slippage on the pressure-driven electrokinetic energy conversion in conical nanochannels are systematically investigated in this paper. We present a multiphysical model that couples the Planck-Nernst-Poisson equations and the Navier-Stokes equation with a Navier slip condition to fulfill this purpose. We systematically look into the variation of various performance indicators of electrokinetic energy conversion, for example, streaming current, streaming potential, generation power, energy conversion efficiency, regulation parameter, and enchantment ratio, with the conicity of nanochannels and the slip length for two pressure differences of the same magnitude but opposite directions. Particularly, enhancement ratios related to streaming current, streaming potential, generation power, and energy conversion efficiency are defined to comprehensively measure the enhancement of the performance of electrokinetic energy conversion due to the slip length. The results demonstrate that a combination of large slip length and small conicity enhances the electrokinetic energy conversion performance significantly. Furthermore, the fluid slippageinduced enhancement of the electrokinetic energy conversion in the backward pressure difference mode is stronger than that in the forward pressure difference mode. Our results provide design and operation guidelines for pressure-driven electrokinetic energy conversion devices.

Energy harvesting from water streaming at charged surface

“…Similar or even higher efficiencies were predicted in simulations by calculating the figure of merit, with consideration of slip length under the fixed surface charge [125, 188]. Other effects, such as inhomogeneity of slipping surface [189], the geometry of channels [190, 191], short channel effect [150], ion types [192], access resistance [149], and microchannels array [151], were considered other effects that might impact the efficiency and output power.…”