Fire Smoke Propagation in Integrated Circuit Manufacturing Facilities under Coupling Effects of Mechanical Smoke Exhaust and Clean Air Supply Systems

Integrated circuit (IC) manufacturing facilities, with their large spaces, high clearances, and unique vertical airflow structures, exhibit distinct fire smoke propagation mechanisms. This study employs Fire Dynamics Simulator (FDS) for numerical simulations based on experimental data from a cone calorimeter (CONE) and thermal property parameters from the Handbook of Plastics, Elastomers, and Composites. It investigates the coupled interaction between mechanical smoke exhaust and clean air supply systems under different operational sequences. Four scenarios were simulated to analyze smoke spread, temperature, CO concentration, and visibility in the vertically connected Cleanroom and Sub-Fab layers. Results indicate that delayed or continuous air supply introduces strong inertial forces, disrupting natural smoke stratification, destabilizing smoke in remote zones, and facilitating its descent into lower spaces, where localized accumulations of toxic gases form in corners. Although the global Richardson number (Ri>140) suggests buoyancy dominance, persistent airflow enhances local inertia, reducing the Smoke Stratification Index (SSI) to 0.003 in far-fire areas and generating corner CO peaks of 5×10 ^-4 mol/mol. A risk transfer mechanism is identified: while continuous air supply delays hazard development in the Cleanroom, it exacerbates toxic gas accumulation in the Sub-Fab and accelerates visibility loss, significantly shortening available safe egress time. These findings provide critical support for performance-based design and ventilation interlock optimization in semiconductor facilities.