US Patent 11851191 Aircraft environmental control system

An environmental control system of an aircraft includes a plurality of inlets for receiving a plurality of mediums including a first medium, a second medium, and a third medium and an outlet for delivering a conditioned flow of the second medium to one or more loads of the aircraft. At least one compressing device is arranged in in fluid communication with the plurality of inlets and the outlet. The at least one compressing device includes a four-wheel compressing device having a compressor and at least one turbine operably coupled via a shaft. In a first mode of operation, the compressor is driven by the first medium, and in a second mode of operation, the compressor is driven by the third medium.