Study On Pyrolysis Kinetics And Radial One-Dimensional Thermal Expansion Of Flame-Retardant Cables

Electricity servers as the driven momentum of the age of artificial intelligence.As the carrier of electricity,the cable has greatly covered all kinds of industries from data communication to rail traffic.However,cable may always correspond to fire hazard due to direct connection to power and the combustibility of the made-up polymers.The retardant technology increasingly improves,but the practical fire resource is very complex and often characterized as high and transient heat flux.In such condition,the fire behavior of the cable is often ignored.Previous study focused on the experimental behavior of cable under constant heat flux and the systematic mechanism and controlling equations has not been built.In this paper,the fire response behavior is studied from view of both micro and macro.Firstly,TGA is conducted for PVC and XLPE at 6 different heating rate in both N2 and Air atmosphere.Then,various kinetic fitting method is applied to obtain kinetic triplets.Finally,a pyrolysis model of radial one-dimensional porous solid materials suitable for cable column structures was developed.Based on the density difference between reactants and solid products,a theoretical model for simulating the overall expansion characteristics of materials was establishedThe kinetic fitting of TGA shows that the fitting results corresponding to kinetic fitting triplets by Single-Scan method agree well with experimental curves.However,the fitting triplets obtained in different heating rates present obvious kinetic compensation effects.Multi-Scan method can relatively reduce KCE,but the fitting curves cannot agree very well with experimental data.Therefore,a new model that kinetic triplets linearly changes with heating rate is proposed.The fitting results show that the new model combines the advantages of both single and multi-scan method and ensure reliable kinetic parameters.Finally,the kinetic dynamic,macro heat transfer and mass transfer is combined to build radical one-dimension pyrolysis-heat transfer-swelling model 1.It's found that the reaction model based on TGA cannot simultaneously fit well with experimental temperature filed,mass loss and swelling progress.Therefore,the variable density of PVC is introduced to partially modify the defects of the reaction model.Numerical results show that the temperature filed and mass loss can be well predicted by modified model.The overall trend of complex and irregular swelling progress can be reflected.