The Study On The Theory And Experiment Of Aerosol Particle Size Measurement Based On Light Scattering Method By Single Particle

Aerosol particles have significant influence on human health,society,environment and industrial production and other fields,the measurement and analysis of aerosol particle size have important implications on environmental quality monitoring,rating and pollutant control of super clean and high-tech processing workshop,scientific research and other fields.The method of aerosol particle size measurement based on light scattering by single particle is an important method for aerosol particle size measurement and particle counting.This widely-used method has the advantages of simple principle and structure,non-contact,wide measuring range and good real-time characteristics.However,theoretically speaking,this method is subjected to measurement errors due to the refractive index of the particles,.In this thesis,study focuses on this defect of the method,the influence of the refractive index on the measurement results under different light-receiving parameters is evaluated.By designing the appropriate light-receiving parameters,the influence of the refractive index on the measurement results can be reduced and the measurement error can be reduced.This thesis mainly completed the following work:1.The Mie scattering theory and its numerical calculation are introduced and studied,and the calculation programs of the scattering intensity and the radiant flux are written by the forward recursive algorithm,which lays the foundation for the subsequent quantitative evaluation and analysis of the influence of the refractive index.2.The composition of aerosol particles and their refractive index are investigated comprehensively.Taking common 13 kinds of particles in the atmosphere as the object of study,the F-D curves of 13 kinds of refractive indices under different light-receiving parameters are calculated.An evaluation standard based on the average relative error of measurement is presented,and the F-D curves of 13 kinds of refractive indices under different light-receiving parameters are analyzed according to the standard,and the quantization value of the influence of the refractive index on the measurement results under different light-receiving parameters is obtained.The results show that if the light-receiving structure is able to receive the radiant flux including the forward scattered light,the F-D curves of the 13 kinds of particles are close to each other,and the average relative error of measurement is small,the influence of refractive index on the measurement results is relatively small.3.Under the condition that the light-receiving parameters is θ=30° and β=29°,the gas path part,the optical part and the signal collecting part are designed,and particle size measurement experimental system of light scattering by single particle is set up.Based on the system,the experimental system was calibrated by PSL standard particles,and the calibration curve is obtained,the accuracy of the calibration curve is verified by using additional PSL standard particles.Finally,the measurement software based on Lab VIEW is written,and the size of unknown particles is measured in real time,and the particle size distribution of unknown particles is obtained so that the feasibility of the experimental system for measurement is verified.