Study of Aldehydes, Carbon Monoxide, and Particulate Contaminants Generated in Bleed-Air Simulator

Abstract

Air travelers breathe a blend of recirculated cabin air and outside air known as bleed air that has been compressed by the aircraft’s engines. Occasionally, engine oil leaks into bleed air, resulting in various chemical contaminants entering the aircraft cabin. Determining the chemicals produced and the oil particle size distribution when bleed air becomes contaminated with engine oil is very important to evaluate potential adverse health effects and to design a sensing system to detect bleed-air contamination in real time. In this research, the type and concentration of different chemicals as well as the number and size distribution of particles were determined for various bleed-air temperatures and pressures generated by a bleed-air simulator. Different aldehydes were formed, and concentrations increased with increasing pressure (200–480 kPa) and temperature (185–310°C). However, at a pressure of 690 kPa, temperature had only minor effects. Carbon-monoxide concentration increased with both increasing pressure and temperature across all temperatures and pressures evaluated. The oil particles produced had their maximum size but minimum number concentration at the minimum bleed-air temperature evaluated, and they had their maximum number concentration in the size of roughly at the maximum temperature and pressure point.