Basic Operations of a Typical Air Cycle Systems
Air cycle machines are not a new technology. At the beginning of the 19th century Air cycle systems used for providing chilling on ships and for food producers and retailers to provide cooling for their food stores. So those days these kinds of air cycle machines were available from companies such as J&E Hall. From the development of the aircrafts people start building pressurised aircraft. So that Air cycle systems approached to aircrafts to provides fresh, temperature-controlled air to an airplane cabin. Air Cycle systems develop in many ways. Present Air cycle systems mainly divided in to 3 types, those are Turbo-compressor air cycle system, Brake turbine air cycle system and Turbo-fan air cycle system. These systems have some differences in circulation and standard for providing air to a cabin and have many other benefits, such as its reliability and environmental impact. For all machines operation engine bleed air will be the main source in normal operation.
The above picture shows an example for a typical turbo-compressor type air cycle machine. In this system the turbine and the compressor connected by a shaft it is supported by bearings. It means turbine driving a centrifugal compressor. The over view of this system is compressor receiving air through a pre cooler (primary heat exchanger) and there is another heat exchanger in between compressor and turbine it call inter cooler (secondary heat exchanger). Those heat exchangers are open to a ram air inlet from that it cools the air in the heat exchanger. The way it works is the bleed air from the engine first enter to the pre cooler then it moves to the compressor section. In compressor the air passing through the diffuser ring. It will increase the temperature and energy in air. Again its go through the inter cooler and it’s enter to the turbine. In the turbine the air directed to the