A multiphase approach for pyrolysis modelling of polymeric materials

Abstract

In this study, a multiphase pyrolysis model has been proposed under the large eddy simulation (LES) framework incorporating moving boundary surface tracking, char formation, and detailed chemical kinetics combustion modelling. The proposed numerical model was applied to simulate the cone calorimeter test of two kinds of materials: (i) pinewood (charring) and (ii) low-density polyethylene (non-charring). Using a cone calorimeter setup, good agreement has been achieved between the computational and the experimental results. The model is capable of predicting the formation of the char layer and thus replicating the flame suppressing thermal and barrier effects. Furthermore, with the application of detailed chemical kinetics, the fire model was able to aptly predict the generation of asphyxiant gas such as CO/CO2 during the burning process. However, the pinewood experiments showed significant CO/CO2 emissions post flame extinguishment attributed to char oxidation effects, which were not considered by the fire model. Despite the limitation, the fully coupled LES model proposed in this study was capable of predicting the fluid mechanics and heat transfer for the turbulent reacting flow, solid-phase decomposition, and gaseous products under flaming conditions. In the future, it can be further extended to include char oxidation mechanisms to improve predictions for charring materials. Keywordspyrolysis char formation detailed chemistry large eddy simulation (LES)

ReaxFF Molecular Dynamics Study on the Microscopic Mechanism for Kerogen Pyrolysis

“…The energy minimization was performed using the conjugate gradient (CG) method. Then, the temperature of the system was controlled using the Nose–Hoover thermal bath method, with a damping coefficient of 100 fs . The simulation was conducted in the NVT ensemble, initially raising the temperature from 0 to 300 K at a rate of 10 K/ps.…”

“…Then, the temperature of the system was controlled using the Nose−Hoover thermal bath method, with a damping coefficient of 100 fs. 25 The simulation was conducted in the NVT ensemble, initially raising the temperature from 0 to 300 K at a rate of 10 K/ps. Once the desired temperature was raised to 300 K, the system equilibrated.…”

Experimental Investigation of the Pyrolysis of Synthetic Materials Exposed to External and Internal Fires

“…The authors of [34] study the pyrolysis phenomenon and investigate experimentally and numerically the combustion of polystyrene and its composites that include modified ammonia polyphosphate and grapheme. During the investigations, we determined the thermodynamics of synthetic materials including the reaction heat, specific heat capacity and the heat conduction that was additionally obtained by the measurement of rate at a mass loss during the tests performed using the conical calorimeter.…”