Concentration Measurement Of CO And H₂O In Flame Using Tunable Diode Laser Absorption Spectroscopy

Combustion is a complex reaction process in which chemical and physical changes are coupled.Monitoring the concentration and temperature of gas components during combustion helps to provide important data support for the optimal design of the burner and improved combustion systems.As a non-intrusive detection technology,tunable diode laser absorption spectroscopy technology has the characteristics of high sensitivity,fast response,strong anti-interference ability.The application of this technique to the measurement of temperature and concentration in flames is of great guiding significance for the study of the mechanism of combustion flame and practical engineering applications.Firstly,the combustion measurement technology was summarized.The basic principles and corresponding technical methods of tunable diode laser absorption spectroscopy were introduced.According to the principle of spectral line selection,four spectral lines near 7154 cm^-1 and7153 cm^-1 were selected for temperature and concentration measurement of H₂O,and the spectral line near 4343 cm^-1 was selected for CO concentration measurement.The accuracy of CO concentration measurement was verified using a high temperature tube furnace system.The results showed that the peak error of CO concentration?1%¹0%?was less than 8%.Then the concentration and temperature of CO and H₂O in methane air premixed plane flame were measured under different equivalence ratios.The feasibility and accuracy of temperature measurement of selected H₂O line were verified by thermocouple temperature measurement system.The peak error between the temperature measurement result of laser spectroscopy and the temperature measurement result of thermocouple was less than 5.3%.In addition,the concentration of gas components under CO₂ and N₂ dilutions was measured,focusing on the effects of CO₂ dilution on CO and H₂O concentrations.In order to further explore the reaction mechanism of CO₂ diluent,the chemical kinetics analysis of the premixed flame was carried out by using the Chemkin software package combined with the GRI3.0 reaction mechanism.The CO concentration,H₂O concentration and flame temperature were calculated separately and compared with the experimental values.The trend of concentration changes was basically the same,which verified the reliability of the reaction mechanism and experimental measurement results.The sensitivity analysis was used to further analyze the CO₂ dilution to H₂O and CO concentration from the mechanism.