Experimental Study On The Ethylene/air Diffusion Flame Based On Near-infrared Emission Spectrometry Measurement

Soot is produced in fuel-rich parts of flames as a result of incomplete combustion of fossil fuels, which will reduce energy efficiency and increase environment pollution as an inefficient energy. So soot has a great impact on human health, environment pollution and industrial applications. Developing soot measurement techniques is important to the research of processing of soot formation and burnout and the validation of soot formation models.The technique for determination of soot temperature and soot volume fraction based on flame emission spectra has been pained extensive attention in recent years, while the near-infrared emission spectrometry measurements of flames are rare. A technique for determination of soot temperature and soot volume fraction based on near-infrared emission spectra information is developed in axisymmetric laminar diffusion flames. Firstly the spectrum radiation model of axisymmetric flame is established, then introduce the Abel inversion to calculate the soot temperature and the soot concentration. At last, provide some data, make analog calculation, rebuild the result in 900-1900nm, 1000-1700nm, 1200-1650nm wavelength bounds, the result is very approximate to the date which we provided; and the rebuild in different noise condition, we also can obtain the ideal result at SNR=200.Measurements are carried out on an axisymmetric ethylene/air diffusion flame using near-infrared spectrometry to obtain line-of-sight emission spectra at five heights of flame. The radiation intensity profiles are obtained using the calibration factor calibrated from blackbody furnace, and then processed a series of data processing such as filter, polynomial fitting and symmetry. The distribution of temperature and soot volume fraction at five heights will be reconstructed. The soot volume fraction at the center of lower part of flame is close to zero, and increase to the peak value at the height of 30mm, and then decrease with the increasing of flame height. The range of soot temperature is 1500~1800K, and that of the soot volume fraction is 0~4.5ppm,which agree well with the results of literature.