The research on More Electric Aircraft has the goal to optimize A/C by replacing conventional systems (e.g., hydraulic and pneumatic) by electric systems, for instance by replacing the bleed air system on the engine with an electrically driven blower system. The Rolls-Royce Trent 1000, currently being developed for the Boeing 787, has this feature, whereas the very similar Trent 1700 on the Airbus A350 will use the conventional system. We did develop a functional simulation which allows us to understand the impact of a bleed-less Aircraft: In current passenger aircraft the air-conditioning system is being run with bleed air. As the temperature of this bleed air is too high to be used for the air conditioning of the cabin, this air needs to be processed. To improve the profitability, the weight and the reliability a new air conditioning concept is being determined. Within this new concept the air conditioning of the cabin is being carried out through specific compressors/ engines.

Modeling of Bleed-less air-conditioning

In the aviation industry the definition of aircraft-systems takes place through a model-based approach, in which every subsystem is described by a mathematical and functional model. The goal of the project is to develop a simulation model for an A/C Air-Conditioning System.
This model allows us to

  • Analyze the relation to the connected systems (Water/Waste, Bleed Air, AFDX, ECS, Anti Icing)
  • Understand the impacts of advanced concepts like bleed-less A/C or More Electrical Aircraft

To be able to run this project, it is necessary to understand the impact of a bleed-less A/C concerning the appropriate control circuits which includes

  • Impact of bleed-air extraction and electrical power on the turbine thrust respectively and fuel consumption
  • Functionality of the „packs“, which are run by bleed-air
  • Air generation system in aircraft without bleed air
  • Control of the cabin pressure with the help of outlet-valves
  • Zonal temperature control achieved by admixing of hot „trim air“
  • Recirculation of cabin air through the filter and mixing unit


  • First version of simplified model including cabin is working
  • Pull up down case (38 to 24 C) and pull up case (-22 to 24 C) in 30 min has be successfully simulated
  • Detailed analysis of enthalpy loss for bleed air would provide more precise results concerning impact on fuel consumption
  • Modeling and Implementation of Bleed air Bleed Air Control System
  • Analysis of the influence of bleed-air consumption on the engine parameters in order to determine the benefit of bleed-less aircraft configurations
  • Bleed-less engines impact on systems and performance