Vehicle air cycle air conditioning system

An air cycle automotive air conditioning system for providing conditioned air to an automotive passenger compartment (20), comprising,

• an air compressor (10) to receive and compress ambient air,
• an air to air heat exchanger (18) to receive compressed air from said compressor (10) and cool it by heat exchange to the ambient,
• a water separator (16) to receive compressed, cooled air from said heat exchanger (18) and remove water therefrom,
• an expander (12) to receive compressed, cooled and dried air from said water separator (16) and expand it to a below freezing temperature, said expander (12) being operationally joined in tandem to said compressor (10) in order to recover work done by said expanding air back to said compressor (10),
• an air inlet valve (30) to selectively provide ambient air, or air from said passenger compartment (24), or a combination thereof, both to said compressor (10) and selectively to another destination
• an air mix temperature control valve (34) to receive both cold air from said expander (12) and a combination of warmer ambient air or passenger compartment air from said air inlet valve (30) and proportion the two air sources into a sufficient volume, mid temperature air flow to be sent to said passenger compartment (24),
• whereby said expander (12) may be run more efficiently to an air temperature below freezing, providing more recovered work to said compressor (10) while the cold air from said expander (12) can be mixed with other air to provide the necessary temperature and flow of air to said passenger compartment (24).