Experimental Measurement And Numerical Modeling Of Particle Deposition In The Environmental Control Systems Of Commercial Airliners

The environmental control system(ECS)of a commercial airplane supplies air to the cabin in order to maintain a safe,comfortable,and healthy environment for passengers and crew members.Because about half of the air supplied to the cabin is outside air,atmosphere particles could deposit in the ECS before entering the cabin.Severe air pollution and poor on-time performance of commercial flights in China may increase particle deposition in ground air-conditioning carts(GACs)and environmental control systems(ECSs).The deposited particles may interfere with GAC and ECS operation.In addition,particles that penetrate into an airplane cabin could adversely affect the health of passengers and crew members.Therefore,it is important to study the deposition of particles in GACs and ECSs.This investigation measured the PM2.5 particle concentrations and the quantities of particles of different sizes at the inlet and outlet of the GAC and ECS in an MD-82 airplane parked next to Tianjin Airport under different air quality index(AQI)values.The results showed that the PM2.5 mass concentration deposition in the GAC and ECS was 40-50%,with most of the deposition occurring in the ECS.For particles with a diameter of 5 ?m or larger,the deposition rate was greater than 90%.For particles with a diameter 0.5 ?m or less,the deposition rate was minimal.In addition,we measured particle mass and number concentration on commercial flights.The results indicated that particle concentrations were high when the airplanes were on ground.This investigation has developed a simplified geometric model for the ECS and an empirical model to calculate the particle deposition rates in the ECS for different particle sizes on the basis of a set of empirical equations from the literature.The model was used to predict particle deposition in five types of commercial airplanes(a regional jet,Boeing 737-800,Airbus 319,Airbus 320,and MD-82).The predicted results were compared with data measured in-flight or during operation on the ground and agreed well with the measured data.Both the simulated and measured results showed that almost all the large particles(dp ? 5.0 ?m)and 75% of small particles(dp=0.3-5.0 ?m)were deposited in the ECS.Most of the particle deposition occurred near the entrance to the ECS where the geometry was the most complex.