| Based on the chemical reaction kinetics, this paper apply the thermal theory to solvethe thermal explosion problem of fireworks and firecrackers and obtain the criticalparameters of steady and non-steady state, including critical ambient temperature, thecenter critical temperature rise, temperature distribution, temperature history, thermalexplosion time to ignition and so on. Then it can be used to evaluate the thermal safety offireworks and firecrackers. The main research contents are as follows:Considering the variation of heat transfer coefficient, steady and non-steady statethermal explosion model of single cylindrical fireworks was established afterconsummation and the boundary conditions was simplified. Influence of variable heattransfer coefficient of fireworks and crackers on thermal explosion critical ambienttemperature and time to ignition was calculated and analyzed. Based on the Matlabplatform, the GUI calculation program was designed for thermal explosion calculation ofsingle cylinder fireworks and firecrackers, which realized the dimension and visualizationof thermal explosion calculation.Based on the theory of steady and non-steady state thermal explosion, the physicalthermal explosion model of battery and three-dimensional cylindrical mathematical steadyand non-steady state thermal explosion model of battery with inhomogeneous heat radiatingof lateral surface was established. By taking advantage of the theory of heat transfer, theboundary conditions were simplified and the equivalent Biot number of lateral surface wasobtained.The thermal explosion combination cylindrical three-dimensional steady and unsteadynumerical calculation method of partial differential equations was established based on theseven point difference method and homotopy continuation method. The Matlab numericalsolution procedure was compiled and the accuracy was verified by comparing thetwo-dimensional thermal explosion computational results with the literature values. Theeffects of the length to diameter ratio, Biot number and other parameters on the criticalityof thermal explosion model were studied based on the thermal explosion calculationprogram of battery (cylindrical combination fireworks and crackers). In addition, a kind ofbattery was carried out with the actual example calculation. The critical parameters ofcylindrical fireworks under different storage forms were obtained, including thermal explosion criterion, the center critical temperature rise, critical ambient temperature,temperature distribution, temperature history, thermal explosion time to ignition etc., andthe thermal safety of battery was analyzed.In this paper, the thermal explosion model of battery was established for the first timeand the problem of three dimensional cylindrical thermal explosion was solved to someextent. The numerical calculation method of three dimensional cylindrical thermalexplosion and the results of this paper lay the foundation for the research of thermal safetyof pyrotechnic products’ warehouse storage, provide basic data and theory guidance forsafety of fireworks and crackers in the production, use, storage and transportation. |
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