Effects of Environment Control System Operation on Ozone Retention Inside Airplane Cabin

High concentration ozone presented at airplane cruise altitudes will enter the cabin with bleed air and threaten occupants’ heath. While current airworthiness standards have regulated the maximum level of ozone permitted, there still is a lack of a thorough understanding of the whole process which affects ozone retention within the whole airplane, especially the influence of airplane environment control system (ECS) operation. We have proposed different analytical models to evaluate the ozone removal efficiency and to consider different flow conditions and deposition mechanisms, including Distributed Parameters Model (DPM) for ECS and steady analytical model for cabin. By taking Boeing model 747-400 as a sample, we found that ECS contributes to overall ozone retention only to a limited extend at under clean conditions. The effects will be enhanced by the chemical reaction between ozone and bleed air contaminants deposited inside ECS and change with the variations of operation conditions, especially the bleed air pressure.