Thermal safety assessment of self-decomposing reactive substances in microchannel transport process: a case of AADE
摘要
During the hazardous synthesis process upgrade, microchannel reactors are replacing batch reactors due to their superior heat and mass transfer. However, the thermal safety of self-decomposing substances in microchannels remains unclear. This study investigates cyclic S-shaped microchannels and Azobenzene-4,4'-dicarboxylic Acid Dimethyl Ester (AADE) particles. A thermal decomposition kinetic model (Sestak–Berggren) was established, showing an average heat release of 853.9 kJ kg−1, a minimum activation energy of 78.6 kJ mol−1, and a thermal runaway temperature of 480 K. The model was coupled with FLUENT-DDPM for numerical simulation. Results indicate that at elbows, local resistance increases, causing particle velocity drops, aggregation, and collision. The most significant temperature rise occurs between monitoring points 5 and 8, indicating low heat exchange efficiency. Decreasing mass flow rate reduces flow inertia, enhances viscous and two-phase coupling effects, leading to flow instability, periodic sliding, and oscillations in velocity and temperature fields. Under conditions of N = 15, M = 1.62 × 10−5 kg s−1, and v0 ≥ 1.8 m s−1, the internal temperature remains below 470 K, well under the thermal runaway threshold. These findings provide guidance for the reaction and transport processes of self-decomposing reactive materials in microchannels.