Study On Morphological And Optical Properties Of Fire Smoke Particle

Soot particles from burning of fuels are great harmful to the human’s health,atmospheric visibility,and global climate.Meanwhile,smoke particles are important characteristic parameters for early fire detection.Therefore,the research and analysis of the morphology and scale distribution of smoke has very important applied value to control environmental pollution,protect human health,and improve product quality.First,a series of experiment were conducted to investigate the morphology and scale distribution of smoke form kerosene,diesel,natural rubber(NR)latex foam,and betula crib at different sampling height,different fuel,and different residence time using a small scale experiment platform.The morphology of smoke was observed by scanning electron microscope(SEM).Then using the corresponding software graphics transaction in this work,the scale distribution of smoke was analyzed.Secondly,Based on the optical properties of smoke,we analyze the principle of the optical detecting.The results show that:The number of soot aggregates increase with the sampling heights.When sampling heights ware not greater than 1.0 m,a great deal of tar adhered on the surface of the sampling grid produced by the burning of the betula crib.The size and thickness of the coating layer decreased as the height increased;as a result,the small particles produced by the burning of the emulsion and diesel could be observed.When sampling heights are greater than 1.0 m,there was less tar adhering on the surface of smoke particles produced by the burning of the betula crib,and the smoke particles appeared as the height increased.A great deal of Ash adhered on the surface of the smoke from the burning of NR latex.It could be observed that the number of soot aggregates increased but it morphology tended to loose with increasing residence time,and the tap of different aggregates increased with increasing residence time.The scale of the primary particle of diesel and kerosene diameter of smoke is in the range of 50-70 nm;for the betula crib,the diameters of these primary particles were within 40-50 nm,which were smaller than those of diesel and kerosene;for the NR foam,the mean diameters of these primary particles were within 60-85 nm,which are larger than those of diesel and kerosene.When sampling height is 0.2 m,the size of soot primary particles tend to fluctuate with increasing residence time.When sampling height is 0.6 m,the size of soot primary particles tend to fluctuate with increasing residence time.The size of soot primary particles diameter of soot were increase with increasing residence time.Finally,the principle and method of optical measurement of the soot particle have been conducted based on the data obtained.The analysis results show that: The soot particle of diesel and betula crib conform to the condition of irrelated scattering,while NR foam reacted against that.Based on the Law of Lambert-Beer and Mie theory,this paper discusses the calculation of the extinction efficiency.The experimental results suggest that the difference of extinction efficiency and scattering efficiency increases as the size of soot primary particles increases,under the condition that the wavelength of incident light is not changed.