Numerical And Experimental Study Of Premixed Combustor And Synthesis Of Carbon Nanotubes

Carbon nanotubes are a remarkable material with many appealing properties.However,there are few synthesis techniques capable of producing nanotubes in large quantities at low-cost.The combustion synthesis method of carbon nanotubes makes it possible to synthesize carbon nanotubes at low-cost,large scale,and in a continuous manner.In this paper,the influence of the structure of the premixed burner on the flame morphology was studied.The main factors affecting the synthesis of carbon nanotubes were analyzed,and the optimal conditions for the synthesis of carbon nanotubes were obtained.In this paper,numerical simulation method is used to calculate the burner model with different structures using COMSOL software.The burner with the optimal structure is used to synthesize carbon nanotubes;the premixed flame under different conditions is calculated by CHEMKIN software to obtain the optimal conditions for the synthesis of carbon nanotubes.At the same time,the calculated results are verified with the experimental data,which proves the rationality of the calculation results and provides predictive function for the combustion synthesis method of carbon nanotubes.The specific conclusions are as follows:?1?These three-dimensional burner model with 26mm,4.0mm,3.0mm,2.0mm,and 1.0mm inlet nozzle diameters was built using COMSOL software.The comparison of model calculation results shows that the optimal diameter of premixed burner copper disc nozzle is1.0mm.Under this structure,the quality of premixed flame is the highest,and the conditions such as temperature and reactant concentration in the same level are the most uniform..?2?In the burner model with a 1.0 mm inlet diameter,the influence of the equivalence ratio of acetylene and oxygen,the flow rate,the inert gas content,and the pressure on the combustion state were calculated.The process conditions for optimum flame morphology in the synthesis of carbon nanotubes are:pressure is 6000[Pa],reactant equivalent ratio is 1.4,inlet air flow is1.2*10^-5[m³/s],the inert gas is argon and the content of argon is 0.2.?3?Under the above-mentioned process conditions of optimum flame morphology,the concentration distributions of CO,H₂,C,OH,H,HCCO,HCO,CH₃ and other intermediate components on the axis are calculated by the CHEMKIN software,thereby the best sampling height is between12mm¹6mm.?4?The influence of flame morphology,equivalence ratio,inlet flow rate and inert gas content on the temperature of the synthesis process were studied through experiments,and the rationality of the three-dimensional combustion model is verified,and the optimal experimental process conditions and simulation analysis results is identical.Meanwhile,the experiments have shown that the catalyst is essential for the synthesis of carbon nanotubes.