The Design Of Atmospheric PM2.5 Automatic Monitoring System Based On Laser Scattering

With the development of the process of industrialization,the air emissions of dust are also increasing,environmental problems what caused by dust pollution has become serious.In order to achieve the purpose of environmental protection,we need to concentration of the dust particles of plant emissions monitoring.Dust concentration measurement method currently a wide range of domestic,it can be roughly divided into two categories: the measurement and non-sampling method to measure the sampling-based approach.With the rapid development of science and technology,the advantages of the use of non-sampling method photovoltaic concentration measurement method has become increasingly pronounced.Non-sampling method is based on photoelectric light scattering principle method.The air dust particles aggregated in light of a certain intensity,its spatial fringe around its concentration to a certain ratio between the scattered light,and by measuring the scattered light collected photocurrent generated to measure the size of the dust concentration.This paper analyzes the hazards of air pollution,dust necessity test description,then introduces the application and development of optical dust test profiles,comparing several common airborne dust testing methods,on this basis,elaborated Mie scattering theory,to further theoretical derivation of the foundation.Second application Mie scattering theory,understand the impact of particle size,refractive index and the wavelength of the incident light intensity distribution of the scattered light is analyzed when small suspended particles in the air,the concentration is relatively low,relatively uniform,Rayleigh scattering formula is derived on the basis of the a theoretical concentration tested under certain conditions.According to this theory the appropriate choice of sensor,the dust concentration in the test system design,application of the system in differentconcentrations measured in the experimental chamber were measured with commercially available data of dust PM2.5 detector comparison,the proposed use of MATLAB and Linear Systems calibration.After calibration showed respirable air pollution index measured results and the market detector converted particulate matter(PM2.5)concentration values are in good agreement.Finally,the result of the calibration error is analyzed.This system use a semiconductor laser as the light source,use photodiode as a photoelectric receiver,use FPGA as the computer control measurement process,processing of the measurement results,with small size,light weight,easy operation,low power consumption.It can be widely used in industrial and mining enterprises in ambient air,the dust concentration in public places such as real-time monitoring.