Development of an innovative Aerosol Sensor based on electrical charge measurement to assess collection efficiency. (ECS)

Abstract

Introduction: Improving the filtration efficiency of electrostatic precipitators requires an understanding of the physical phenomena involved in their operation. Numerical methods have also enabled significant progress to be made in the sizing and general architecture of any filtration system. However, the operation of these filters is not always stable, and fluctuations in filtration efficiency frequently occur, necessitating the implementation of a monitoring system and permanent quantification of discharge concentrations [1-2]. Consequently, the detection, sampling and counting of these particles using precise instruments are of paramount importance in preserving air quality [3]. Most of these instruments, currently indispensable to any filtration process, operate intermittently and can only analyze a puncture of the total polluted flow.

Objective: The detection and measurement of airborne solid or liquid aerosol particles with aerodynamic diameters between 1 nm and 100 μm has become an important topic in air pollution monitoring and source characterization. In recent years, there has been considerable interest in submicron aerosol particles, defined as suspended aerosol particles with aerodynamic diameters of less than 2.5 μm, for two main reasons. Firstly, these particles have been associated with adverse health effects in areas of high concentration, and secondly, aerosols are believed to have a significant influence on atmospheric quality, local and global climate and processes in various industries such as food, pharmaceutical and medical, electronics and semiconductor [4]. To this end, aerosol particle instruments have been developed to monitor indoor and outdoor aerosols in the pollution and process control industries [5-6]. A number of commercial instruments are available, using various methods to detect and measure the size distribution and number or mass concentration of particles. Available instruments include a Palas Model Welas-1000 granulometer based on the use of a white light source [7], a Scanning Mobility Particle Analyzer (SMPS) using the electrical mobility of particles [8], a condensation particle counter (CPC) using particle growth and optical properties [9-10], an electrical aerosol detector (EAD) using the electrostatic charge measurement technique [11] and an electrical low-pressure impactor (ELPI) using particle inertial impact under low pressure [12]. These commercial instruments are widely used

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Abstract

to measure airborne ultrafine particles and provide high-resolution measurements, but they are very expensive and large in size. The present manuscript is structured around three chapters. In the first chapter, we present a literature review on electrostatic precipitation as an air pollution control tool and the applications of discharges for particle charging and collection, taking care to recall pollution vectors and air pollution control techniques, before going into detail on what electrostatic precipitation encompasses by reviewing the processes involved upstream, during and downstream of the phenomenon. The second chapter focuses on the detailed description and definition of the characteristics of the various device components, as well as the measurement protocols and techniques used for the different experimental rigs. Finally, the third chapter looks at a new aerosol presence detection system that detects particles suspended inside a capacitive electrostatic sensor (ECS) connected to a sensitive electrometer, in order to assess the collection efficiency of precipitators. We conclude with some conclusions and prospects.