Global warming is a world-wide problem caused by the increasing concentration of CO2 and other products of combustion in the atmosphere. The world community is striving to stabilise, or even reduce, the output of CO2, and therefore every source of this greenhouse gas must be accounted for. The commercial aviation industry is in an especially unenviable position, as the present annual growth of 5% is greater than that of any other sector contributing to the world-wide CO2 output. It is necessary therefore to consider and investigate every considerable measure which would have the potential to reduce the atmospheric emission of CO2, or indeed aircraft fuel consumption in general.

One such measure is the development of more fuel efficient aircraft engines. Considerable progress has been made in this direction in the past;

however, the continual increase in the pressure ratio and combustor exit temperatures of gas turbine engines needed for improved fuel efficiency has been accompanied by an undesirable increase in the NOx emissions. The inter-cooled recuperative gas turbine offers the best possibility of solving the emissions problem, as it is designed to substantially lower fuel consumption at low pressure ratio. For this reason, the inter-cooled recuperative engine can simultaneously reduce both CO2 and NOx emissions.

The exhaust gas recuperator (hex), whose design and development was the content of this project, is one of the key components of the Inter-cooled Recuperative Aero-engine (IRA).