Electrokinetic energy conversion of electro-magneto-hydro-dynamic nanofluids through a microannulus under the time-periodic excitation

Guangpu Zhao,Yongjun Jian,Jiali Zhang,Zhiqiang Wang

doi:10.1007/s10483-021-2745-5

Abstract

In this work, the effects of externally applied axial pressure gradients and transverse magnetic fields on the electrokinetic energy conversion (EKEC) efficiency and the streaming potential of nanofluids through a microannulus are studied. The analytical solution for electro-magneto-hydro-dynamic (EMHD) flow is obtained under the condition of the Debye-Hückel linearization. Especially, Green’s function method is used to obtain the analytical solutions of the velocity field. The result shows that the velocity distribution is characterized by the dimensionless frequency Ω, the Hartmann number Ha, the volume fraction of the nanoparticles φ, the geometric radius ratio a, and the wall ζ potential ratio b. Moreover, the effects of three kinds of periodic excitations are compared and discussed. The results also show that the periodic excitation of the square waveform is more effective in increasing the streaming potential and the EKEC efficiency. It is worth noting that adjusting the wall ζ potential ratio and the geometric radius ratio can affect the streaming potential and the EKEC efficiency.

Highlights

With the tremendous progress of micro-electro-mechanical-systems (MEMS) and microfluidic technology, the research on it has become very hot, and a series of efforts have c The Author(s) 2021Guangpu ZHAO, Jiali ZHANG, Zhiqiang WANG, and Yongjun JIAN been made in many fields, such as chemical separation devices, heat exchange, micropumps, biomedical diagnosis, and lab-on-a-chip systems[1,2,3]
This can be explained that square waveform and triangular waveform can be superimposed to provide large amounts of mechanical energy to be converted into electrical energy, which makes the streaming potential increase, making the electrokinetic energy conversion (EKEC) efficiency increase significantly
The results show that the velocity distribution decreases with the increase in the volume fraction and frequency, and the streaming potential and the EKEC efficiency decrease

Summary

Introduction

In these applications, electric field, pressure gradient, magnetic field or their combination are usually used to drive fluid flow. Flow analysis in microchannels must consider the existence of EDL. This is due to the interaction between the charged wall and the ionized solution[9]. The Stren layer and the diffusion layer formed at the solid-liquid interface constitute an EDL

Methods

Results

Conclusion