Prediction Method of Steady Concentration of Passive Contaminant in Ventilation System with Air Recirculation: Contaminant released in the air duct

School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China

^* Corresponding author: shaoxl@ustb.edu.cn

Abstract

When the hazardous substances are released in the air duct of the ventilation system, they are transported into the room through the supply air inlets, causing harm to indoor personnel. In the ventilation system with air recirculation, the contaminant entering the room is recirculated to the ventilation system through the return air outlet, and then affects the contaminant concentration in supply air, making it difficult to be determined. In this work, a method is proposed to predict the steady concentration of passive contaminant when the contaminant is released in the air duct. The method is based on the fixed flow field in the room. The lumped parameter method is utilized to establish the relationship between the concentrations of contaminant in the inlet and outlet for each air duct and the air handling unit. The linear superposition relationship based on the accessibility index is adopted for the steady concentration at an arbitrary position in the room. The proposed method is compared with the prediction with the lumped parameter method in the room. It can rapidly predict the contaminant distributions in all the rooms supplied by the ventilation system with air recirculation.