A Study on Dead Zone Relocation and Ventilation Efficiency Improvement via Local Temperature Control

This study investigates the formation of dead zones and ventilation inefficiency in a vertical laminar-flow cleanroom caused by heat-generating semiconductor equipment. Computational Fluid Dynamics (CFD) analysis was conducted on a university-scale cleanroom to evaluate airflow characteristics using air age, turbulence intensity, and ventilation efficiency as key performance indicators. The interaction between downward supply airflow and buoyancy-driven thermal plumes was found to destabilize laminar flow, resulting in localized stagnant regions. To address this issue, a localized temperature control strategy was proposed, in which the supply air temperature of fan filter units (FFUs) adjacent to dead zones was selectively reduced without altering the existing structural layout. Sensitivity analyses were performed to identify the most influential inlet locations and optimal cooling ranges. The results demonstrate that localized cooling generates a stabilizing downward buoyancy effect, effectively relocating and reducing dead zones while improving overall ventilation efficiency. Furthermore, an objective-function- based evaluation confirmed that the proposed strategy achieves significant airflow improvement with minimal additional energy consumption. This approach provides a practical and cost- effective solution for optimizing airflow management in existing semiconductor cleanrooms.