Patent attributes
An air conditioning system is provided that includes first and second turbines and a compressor. The second turbine is in fluid communication with a pack outlet. A passage fluidly connects the first turbine and the pack outlet. A valve is associated with the passages and is movable between open and closed positions. In the open position, the valve permits flow through the passageway from the first turbine directly to the pack outlet thereby bypassing the second turbine and reducing the resistance to the flow through the system. The valve is opened at higher altitudes to change the typical series fluid connection between the turbines to a parallel fluid connection. In this configuration, the air conditioning system operates more efficiently using reduced air pressure provided to the system. Another valve is also opened to permit additional reduction in the air pressure required.