A comprehensive experimental study of the premixed ethylene/oxygen/argon flame at 2.667 kPa with a stoichiometric equivalence ratio （Ф=1） was performed with the tunable synchrotron photoionization and molecular-bea...A comprehensive experimental study of the premixed ethylene/oxygen/argon flame at 2.667 kPa with a stoichiometric equivalence ratio （Ф=1） was performed with the tunable synchrotron photoionization and molecular-beam sampling mass spectrometry techniques. The isomers of most observed species in the flame were unambiguously identified by measurements of the photoionization etticiency spectra, e.g. C3H4, C2H4O and C4H4. The mole fraction profiles of species up to C7H8 were measured by scanning the burner position at the selected photon energies near ionization thresholds, and the flame temperature profile was obtained by using Pt/Pt-13%Rh thermocouple. Compared with the previous studies, a lot of new flame species： C3H2, C3H3, C3H5, C2H6O, C4H2, C4H4, C4H6, C3H4O, C3H6O, C3H8O, C5H6, C4H8O and C7H8, were observed. A series of free radicals in the flame are detected to be CH3, C2H3, C2H5, HCO, C3H3 and C3H5. Based on the experimental work, a reduced reaction mechanism was developed including 40 species and 223 reactions. Modeling and measurements agree well for the major species and most intermediates. A detailed kinetic model is desired for this flame.展开更多
Recently,plasma-assisted combustion has become a potentially applicable technology in many combustion scenarios.In this paper,a dielectric barrier discharge（DBD） plasma generator is designed to explore the effect of...Recently,plasma-assisted combustion has become a potentially applicable technology in many combustion scenarios.In this paper,a dielectric barrier discharge（DBD） plasma generator is designed to explore the effect of plasma on the CH4 oxidation process,and several properties of combustion are considered.First,in the presence or absence of plasma discharge,physical appearance of the flame is examined and analyzed.Second,the flame propagation velocity is calculated by the flame front extracted from the imaging data with the Bunsen burner method.Finally,the main molecular components and their intensity variation in the flame and the plasma zones are identified with an emission spectrograph to analyze the effect of active species on the combustion process.We also discuss the possible kinetic regime of plasma-assisted combustion.Experimental results imply that plasma discharge applied to the premixed CH_4/O_2/He mixture significantly raises the flame speed with equivalence ratios ranging from 0.85 to 1.10,with the flame speed improved by 17%to 35%.It can be seen that plasma can improve methane oxidation efficiency in the premixed fuel/oxidizer,especially at a low equivalence ratio.展开更多
Preparation of superfine magnesium hydroxide with the bittern and ammonia was studied. The properties of the products were analyzed by laser granularity, X-ray diffraction, scanning electron microscope, the limiting o...Preparation of superfine magnesium hydroxide with the bittern and ammonia was studied. The properties of the products were analyzed by laser granularity, X-ray diffraction, scanning electron microscope, the limiting oxygen index and the wetting angle measurements. The results show that the mean particle size of the magnesium hydroxide is about 230 nm with a platelet shape and the specific surface area is about 48 m2/g when the temperature is 55 ℃ , and the ammonia and bittern are instilled simultaneously during the reaction process. After the modification, the limiting oxygen index and physical chemistry performance of the magnesium hydroxide were examined. The results show that the contact angle of magnesium hydroxide is 132.5? and the limiting oxygen index is 31.5 %, indicating that the modified magnesium hydroxide is an effective flame retardant and can be applied as flame retardant additives of the macromolecule compounds such as plastic, synthetic rubber and synthetic fibre.展开更多
Used as flame returdant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, ...Used as flame returdant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame- retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained ; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel patement.展开更多
The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder esc...The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder escape and rescue and harms heavily traffic safety.The common flame retardant system is used to modify the asphalt.Cone Calorimeter is adopted to evaluate the burning property of asphalt.The performance of the flame retardant is evaluated by limiting oxygen index and orthogonal design method.The paper analyzes the synergism of the asphalt and flame-retardant,and analyzes the effect of the flame on preventing the smoke to spread and demonstrates that the use of common flame retardants which is added into binder is good at reducing the flammability of the binder.This way can increase the safety of asphalt pavement when fire occurs in the tunnel.The study suggests that flame retardancy of asphalt can be evaluated by Limit Oxygen Index (LOI) and the flame retardancy property of asphalt has marked change according to the content of flame retardant.SB has perfect flame retardancy property,and ATH is better than MH in the effect of flame retardant.展开更多
基金Ⅵ. ACKN0WLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20473081 and No.20533040）, and Chinese Academy of Sciences. The authors are also thankful for the valuable help in the experimental work from Aigou Zhu. Fei Qi thanks the Combustion Research Facility of Sandia National Labs to provide a Chemkin program package for kinetic modeling study.
文摘A comprehensive experimental study of the premixed ethylene/oxygen/argon flame at 2.667 kPa with a stoichiometric equivalence ratio （Ф=1） was performed with the tunable synchrotron photoionization and molecular-beam sampling mass spectrometry techniques. The isomers of most observed species in the flame were unambiguously identified by measurements of the photoionization etticiency spectra, e.g. C3H4, C2H4O and C4H4. The mole fraction profiles of species up to C7H8 were measured by scanning the burner position at the selected photon energies near ionization thresholds, and the flame temperature profile was obtained by using Pt/Pt-13%Rh thermocouple. Compared with the previous studies, a lot of new flame species： C3H2, C3H3, C3H5, C2H6O, C4H2, C4H4, C4H6, C3H4O, C3H6O, C3H8O, C5H6, C4H8O and C7H8, were observed. A series of free radicals in the flame are detected to be CH3, C2H3, C2H5, HCO, C3H3 and C3H5. Based on the experimental work, a reduced reaction mechanism was developed including 40 species and 223 reactions. Modeling and measurements agree well for the major species and most intermediates. A detailed kinetic model is desired for this flame.
基金supported by the Fundamental Research Funds for the Central Universities of China(No.xjj2013086)Natural Science Basic Research Plan in Shaanxi Province of China(No.2014JQ7254)National Natural Science Foundation of China(No.51477135)
文摘Recently,plasma-assisted combustion has become a potentially applicable technology in many combustion scenarios.In this paper,a dielectric barrier discharge（DBD） plasma generator is designed to explore the effect of plasma on the CH4 oxidation process,and several properties of combustion are considered.First,in the presence or absence of plasma discharge,physical appearance of the flame is examined and analyzed.Second,the flame propagation velocity is calculated by the flame front extracted from the imaging data with the Bunsen burner method.Finally,the main molecular components and their intensity variation in the flame and the plasma zones are identified with an emission spectrograph to analyze the effect of active species on the combustion process.We also discuss the possible kinetic regime of plasma-assisted combustion.Experimental results imply that plasma discharge applied to the premixed CH_4/O_2/He mixture significantly raises the flame speed with equivalence ratios ranging from 0.85 to 1.10,with the flame speed improved by 17%to 35%.It can be seen that plasma can improve methane oxidation efficiency in the premixed fuel/oxidizer,especially at a low equivalence ratio.
基金Project(2002-G-101) supported by the Key Program of Science and Technology of Qinghai Province, China
文摘Preparation of superfine magnesium hydroxide with the bittern and ammonia was studied. The properties of the products were analyzed by laser granularity, X-ray diffraction, scanning electron microscope, the limiting oxygen index and the wetting angle measurements. The results show that the mean particle size of the magnesium hydroxide is about 230 nm with a platelet shape and the specific surface area is about 48 m2/g when the temperature is 55 ℃ , and the ammonia and bittern are instilled simultaneously during the reaction process. After the modification, the limiting oxygen index and physical chemistry performance of the magnesium hydroxide were examined. The results show that the contact angle of magnesium hydroxide is 132.5? and the limiting oxygen index is 31.5 %, indicating that the modified magnesium hydroxide is an effective flame retardant and can be applied as flame retardant additives of the macromolecule compounds such as plastic, synthetic rubber and synthetic fibre.
文摘Used as flame returdant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame- retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained ; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel patement.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 50078057)Program for New Century Excellent Talents in University(Grant No. NCET-06-0340)
文摘The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder escape and rescue and harms heavily traffic safety.The common flame retardant system is used to modify the asphalt.Cone Calorimeter is adopted to evaluate the burning property of asphalt.The performance of the flame retardant is evaluated by limiting oxygen index and orthogonal design method.The paper analyzes the synergism of the asphalt and flame-retardant,and analyzes the effect of the flame on preventing the smoke to spread and demonstrates that the use of common flame retardants which is added into binder is good at reducing the flammability of the binder.This way can increase the safety of asphalt pavement when fire occurs in the tunnel.The study suggests that flame retardancy of asphalt can be evaluated by Limit Oxygen Index (LOI) and the flame retardancy property of asphalt has marked change according to the content of flame retardant.SB has perfect flame retardancy property,and ATH is better than MH in the effect of flame retardant.
