[The control efficacy of parallel flow push-pull ventilation systems on nitrogen tetroxide in high-bay spaces]

Objective: To investigate the rationality and effectiveness of using a parallel flow push-pull ventilation system to control nitrogen tetroxide gas in high-bay spaces. Methods: In May 2024, a nitrogen tetroxide-contaminated ignition test chamber at a research institute was selected as the study subject. Field investigations, environmental monitoring, computational fluid dynamics (CFD) simulations, and ventilation effectiveness evaluations were conducted to design a parallel flow push-pull ventilation system. The concentration changes of nitrogen tetroxide (measured as nitrogen dioxide) before and after the renovation were detected and compared, workplace toxicant control efficiency was calculated, and the ventilation system's performance was comprehensively assessed. Results: After the renovation, the overall airflow organization in the ignition test chamber and the breathing zone height exhibited a unidirectional southward flow. The time-weighted average concentration (C(TWA)) of nitrogen dioxide decreased from 8.53 to 1.45 mg/m(3). The short-term exposure concentration (C(STEL)) at 8 detection points in the test chamber decreased from 14.3-72.8 mg/m(3) to 3.2-9.8 mg/m(3). The control efficiency of nitrogen tetroxide at the position was all above 80% except for the detection point 1 directly facing the north gate of the test room. Conclusion: The parallel flow push-pull ventilation system can establish stable unidirectional laminar airflow in high-bay spaces, effectively resist ambient interfering airflow. It achieves efficient containment of nitrogen tetroxide gas while effectively protecting air quality in the work area, confirming its rationality and effectiveness in similar workplaces with highly toxic substance exposure.