Application research on controlled environmental pressure difference control based on variable air volume control

Pressure difference control is a core part of controlled environmental airflow control, providing robust safeguards to achieve directional airflow control objectives and enhance overall laboratory safety. Based on the factors such as airtightness characteristics of the envelope, pressurization control requirements, and fast disturbances, this study taking ordinary laboratories, standard cleanrooms, and airtight biosafety laboratories as examples, explores the applicability, influencing factors, and mitigation strategies of three pressure difference control methods including volumetric flow tracking control, direct pressure difference control, and cascade control under variable air volume (VAV) control, and the applicability of the air infiltration characteristic equation. The research shows that in ordinary laboratories and standard cleanrooms, airflow near intentional openings and gaps in the envelope approaches turbulent flow, with a flow exponent (n) value of 0.5. In contrast, in airtight laboratories, where the ratio of gap length to hydraulic diameter in the envelope is high, laminar flow predominates, with the flow exponent (n) value approaching 1.0.