Environmental Control Systems

Abstract

An aircraft environmental control system is tasked with maintaining on-board conditions suitable for equipment operation, and comfortable for vehicle occupants. This chapter covers systems in use today to provide environmental control on aircraft, with both open loop air cycle and closed loop vapor cycle systems described. The major environmental control system components and sub-systems are then considered in more detail. This includes humidity and pressure control components and principles of operation, ozone conversion performance, filtration of recycled cabin air, cold air units (bootstrap machines) operation and design, and the use of heat exchangers. Oxygen provision systems are also considered in the form of liquid oxygen (LOX) systems and on-board oxygen gas generation systems (OBOGGS). This chapter culminates by bring many of the aforementioned sub-systems and components together to present and describe an environmental control system that is typical of that used on many aircraft presently in-service.