| Soot is an incomplete product of fuel combustion and an important factor that causes energy loss and environmental pollution.At the same time,smoke is also the culprit for most of the casualties caused by fire accidents.The smoke will cause a reduction in the visibility of the fire field and cause evacuation difficulties to people,soot particles can also be directly inhaled into the human respiratory tract,causing suffocation casualties.Therefore,the accurate determination of the soot content in the fuel combustion process,as well as the soot generation characteristics and influencing factors have important social application value to achieve a reduction of the soot emissions of the combustion process in order to improve energy efficiency,reduce environmental pollution,and reduce casualties in fire accidents.The fast and accurate acquisition of the soot content in the flame is a prerequisite for in-depth study of the soot formation characteristics and the method for controlling the amount of smoke emitted.Comprehensive comparison of existing soot detection methods,select the method of Light extinction(LE)with high accuracy and relatively low experimental cost as the basic technical means of this study,through the in-depth study of the solving algorithm of Light extinction method,based on the Matlab platform,a set of software programs for image processing and solving algorithm of Light extinction method are developed,and an Light extinction experiment platform is built independently to obtain four images of a laser flame image,a flame image,a laser image,and a background image as the original data for the calculation of the Light extinction method.In order to verify the reliability of the algorithm program and the experimental platform,the ethylene/air and propane/air laminar diffusion flames were used as experimental objects to carry out test experiments.The test results were compared with the literature results.The results showed that the flames of ethylene and propane The test results show a high consistency with the literature results.The peak relative error at different heights is basically controlled within 8.13%,and the main error comes from the flame root and the flame tip which highly affected by the flame morphology,in the middle of the flame.The peak relative error of the soot volume fraction at the same height in the radial direction is basically controlled within 3.84%.In summary,the Light extinction experimental platform and the self-programmed algorithm program constructed in this study have high reliability and applicability to the determination of soot content in hydrocarbon flames.In order to further discuss the influence of water vapor content on the soot generation characteristics in hydrocarbon flames,a set of atomization and humidification equipment was added to the Light extinction test system to conduct the determination of the soot concentrations of ethylene and propane flames under different water vapor contents.Through the experiment which conducted on 5 conditions of 0%,5%,8%,12% and 15% water vapor content,the results showed that: in the form of flame,an increase in water vapor content can lead to a darkening of the flame brightness and cause a stretching effect to the flame.In the soot content,the increase of water vapor content will cause the overall level of soot content in the flame to decrease,but the suppression effect will gradually decrease as the flame height increases.In addition,through the detailed discussions on the three effects of the temperature effect,oxygen dilution effect,and chemical reaction effect proposed by the former on the mechanism of the influence of steam on the soot generation characteristics of the flame,it was found that this conclusion has a high degree of applicability in the experimental results of this study.The applicability demonstrates the reliability of the conclusion and shows that the results of this experiment have high accuracy and applicability. |
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