Liebherr is the only supplier in the industry who develops the air cycle machine in-house - thus being the expert in air cycle air conditioning.

Air cycle air conditioning systems work with air as cooling medium and are therefore totally environmentally benign.

The air cycle system is by far the air conditioning system that allows to reach the lowest life cycle cost (between 20% and 40% lower than traditional technologies) when considering the rail vehicle’s total operation lifetime (more than 30 years).

The systems operate either with an open loop or with a closed loop architecture., In any case they are based on the principle of expanding the air through a turbine to bring its temperature down.

In comparison with the closed systems that are now available on the market, the advantage of the open loop process is that in case of any minor air leakage which may develop in time, the system will continue to function with only a tiny reduction in cooling efficiency. The heat exchange with the air supplied into the passenger’s space continues independently and is separated from the air cooling process. The pen loop process offers the largest possible resistance to defects and the highest reliability with a smaller number of components.

Liebherr’s air cycle air conditioning systems consist of four main components only:

• Supply air fans for air movement,
• a motorized air cycle machine/turbine (the process air is expanded here and therefore cooled),
• a heat exchanger (the cooled air flows through it and is used to cool the warm outside air, the warm process air is compressed in the compressor and fed back to ambient)
• an electric heating system for heating the cold outside air when required by using resistive heating elements.

The system’s architecture is optimized for lowest internal pressure losses, light weight and high levels of efficiency.