Clarence Lui

Recirculating Regenerative Environmental Control System

The rapid increase of liquid cooling demand from high-power and high-density avionics in military aircraft has been a challenge for aircraft cooling system designers. A number of state-of-the-art approaches were presented in SAE 2003-01-2399. This paper is a continuation of that discussion on the advancement of environmental-control-system design to meet the higher demands for liquid cooling. In this paper, another advanced environmental control system will be presented. The advanced system is one of a new generation of bootstrap air-cycle cooling systems. Similar to a traditional bootstrap air-cycle system, the advanced system is powered by high-pressure engine bleed air and uses ambient ram air and/or on-board fuel as a heat sink. However, unlike a typical air-cycle system, the advanced system maximizes usage of engine bleed pressure to form a recirculation flow path. It is also able to recover waste energy from electronics equipment, so as to maximize re-use of aircraft-generated energy to boost system efficiency. This new approach will significantly reduce bleed-air consumption and heat-sink demand, both of which are key parameters for energy-efficient aircraft design.