Combined Image Processing and Equivalent Circuit Approach for the Diagnostic of Atmospheric Pressure DBD

Abstract

The framework of this paper is the study of gas treatments (NOx abatement) by dielectric barrier discharge (DBD) at atmospheric pressure. To investigate the impact of various solutions for electrical energy injection on the treatment process, two diagnostic methods are considered to evaluate the discharging ratio on the reactor surface: an image processing method and a DBD equivalent circuit analysis, both presented in this paper. For the image analysis, the discharge area is first translated into gray levels, then segmented using the Otsu’s method in order to perform the discharging ratio diagnostic. The equivalent circuit approach, derived from the classical Manley’s diagram analysis, includes the behavior of the part of the reactor in which no discharge is happening. The identification of its parameters is used to estimate the discharging ratio, which evaluates the percentage of the reactor surface covered by the discharge. Experimental results with specifically developed power supplies are presented: they show a good agreement between the two methods. To allow a quantitative comparison of the discharge uniformity according to the operating conditions, the statistical analysis of gray level distribution is performed: non-uniform discharges with intense energy channels are shown to be clearly distinguished from more diffuse ones.