Analysis of Energy saving between Bleed Air and Bleed less Environmental Control Systems in a typical Aircraft

Abstract

Normally, the required quantity of hot air is drawn from an engine compressor for an Aircraft Environmental Control System (ECS). The present work aims to illustrate the energy saving that can be realized by using a bleed-less aircraft environment control system (ECS) that is powered by an auxiliary ram air compressor: This paper presents a direct comparison between the energy consumption of a conventional bleed air system and a bleed-less ECS. A conventional bleed air ECS system is first modeled using MATLAB and validated with results in the open literature. The system is modeled to match the temperature profile with that of an Airbus 320 during cruise conditions. Then, a bleed less system is modeled by modifying the bleed air system to use a ram-air compressor for the air intake as a bleed less ECS. Finally, the fuel mass penalties associated with each environment control system are calculated. The bleed air system incurs fuel penalties due to bleed air extraction, and additional drag due to the ram air intakes for the large heat exchanger ram-air scoops. Whereas the bleed-less system incurs penalties due to drag from the small ram-air intakes for the heat exchanger and the ram air compressor scoop and a dedicated electrical power system for the ram air compressor. It was found that the total fuel mass penalties calculated for the bleed less system are about 80% lesser compared to a conventional bleed air ECS without a dedicated electrical power system.