The Research And Development Of Particulate Mass Concentration Sensor Based On Light Scattering Method

Rapid and accurate detection of the mass concentration particles in the running gas has a very important practical significance. The traditional filter weighing method has its limitation. This paper does the research on Light scattering method particle to detect mass concentration of population.Then, this paper introduce the actual object we made.The main tasks are as follows:Firstly, the theoretical research and MATLAB simulation. Basing on the optical equivalent spherical particle diameter, the paper conducts the particles flux modeling formulas. So We can obtain the linear theory about mass concentration of the particles and Luminous flux.Secondly, this paper should finish the optical structural design of sensor. This paper begins to determine the lighting source selection,the size of the photosensitive area, the photodiode selection, the design of light trap. All this work is based on the above theoretical research and with the help of relevant literature.Last, this paper finish assembling the sensor.Thirdly, this paper finishes a weak signal processing circuit design and makes the actual object. First, we make the model of lock-in amplifier.This paper starts to design and make the preamplifier circuit, fourth-order band pass filters, multipliers and phase locked loop demodulation circuit and a light source drive circuit. Then, this paper does some circuit simulations of above circuit.Fourthly, experimental data processing and measuring the performance of the sensor. And this paper mainly completes the particle generator test, temperature compensation, the sensor calibration. So, this paper determines the mass concentration conversion coefficient K, the minimum measured concentration, the minimum effective concentration of the resolution, the maximum measuring range, and based on above work,this paper does the absolute error analysis and the relative error analysis.