Comparison of discharge mechanism of negative corona between hyperboloid and hemispherical electrodes

B X Lu,J J Zhu

doi:10.1063/1.5054171

Abstract

Electrostatic precipitators based on corona discharge are a research hotspot in recent years. It is of great significance to investigate the characteristics of corona discharge under different system parameters for improving the dust removal efficiency. In this manuscript, the continuity equations coupled with Poisson’s equation are solved by the finite element method (FEM) to explore the different mechanisms of the generation of Trichel pulses when hyperboloid and hemispherical electrodes are used in negative corona discharges for a needle-plate configuration under atmospheric pressure. The fitting curve of the Trichel pulse frequency versus systematic macro parameters, including the applied voltage, the needle tip radius and the needle-plate distance, are given and their mechanisms are analyzed. Subsequently, the features of the Trichel pulses of the hyperboloid electrode and the hemispherical electrode at similar power are compared. From precipitation point of view, the hemispherical electrode is obviously better than hyperboloid electrode.

Highlights

The simulation results for hyperboloid electrode satisfy the empirical formula of Trichel pulse frequency given by Lama and Gallo through experiment:[13] f
Simulation results of Trichel pulses for hyperboloid electrode had been given in several References 17, 20, for hemispherical electrode are seldom seen
In order to further compare the discharge characteristics between the hemispherical and hyperboloid electrodes in negative discharge, the same needle tip radius(250μm) and needle-plate distance(3.3mm) are adopted, and the power consumed by the discharge of two electrodes is approximately equal to each other by adjusting the voltage

Summary

INTRODUCTION

Corona discharge is self-maintained discharge in non-uniform electric field.[1,2,3,4] In recent years, with the increasingly serious air pollution, corona discharge has attracted broad attention for its application in atmospheric controlling.[5,6,7,8] In the needle-plate model, when a certain range of negative voltage is applied to the electrode with smaller curvature radius, a chain of regular pulses with short rising time and relatively long intervals can be observed, known as Trichel pulses.[9,10,11,12] Experiments[13,14,15,16] and numerical simulations[17,18,19,20,21] were carried out to study this issue these years. The shape of electrodes has significant influence on dust removal efficiency in electrostatic precipitators.[22,23,24] it is necessary to further explore the effects of electrode shape on discharge characteristics. In this manuscript, the relationships between Trichel pulse frequency and systematic macro parameters for both hyperboloid and hemispherical electrodes are studied respectively through numerical simulation. The discharge characteristics will be compared between the hyperboloid electrode and the hemispherical electrode under similar average power. Comparative study of discharge characteristics between hemispherical electrodes and hyperboloid electrodes has not yet been found in references

Physical model

Governing equations

RESULTS AND DISCUSSION

CONCLUSION