An airplane is provided. The airplane includes a pressurized volume and an air conditioning system. The pressurized volume provides a first medium. The air conditioning system includes a heat exchanger and a compressor. The heat exchanger transfers heat from a second medium to the first medium. The compressor receives the second medium. The compressor is upstream of the heat exchanger in a flow path of the second medium.

An air conditioning system for an aircraft is provided. The air conditioning system includes a first rotating component and a second rotating component. The first rotating component includes a compressor and a turbine. The compressor pressurizes a first medium. The first turbine receives a mixture of a second medium and a pressurized form of the first medium. The second rotating component includes a fan.

An airplane is provided. The airplane includes a first medium, a second medium, and an air conditioning. The air conditioning system includes a first turbine, a compressor, and a mixing point. The compressor is located upstream of the turbine in a flow path of the first medium. The mixing point is a location at which the first medium mixes with the second medium. The mixing point is downstream of the compressor and upstream of the turbine.

An airplane is provided. The airplane includes a pressurized volume and an air conditioning system. The air conditioning system includes a compressor configured to receive a flow of a first medium, a turbine downstream of the compressor in a flow path of the first medium, a first valve that diverts the flow of the first medium around the turbine, a second valve that provides a second medium to the turbine, and a third valve downstream of the turbine that directs an outlet flow of the turbine towards the pressurized volume and that directs the outlet flow of the turbine away from the pressurized volume.

An air cycle machine for an environmental control system for an aircraft is provided. The air cycle machine includes a compressor configured to compress a first medium, a turbine configured to receive second medium, a mixing point downstream of the compressor and downstream of the turbine; and a shaft mechanically coupling the compressor and the turbine.

An airplane is provided. The airplane includes a compressing device. The compressing device includes a turbine with a first inlet and a second inlet. The turbine provides energy by expanding mediums. The first inlet is configured to receive a first medium of the mediums. The second inlet is configured to receive a second medium of the mediums. The compressing device includes a compressor and a motor. The compressor receives a first energy derived from the first and second mediums being expanded across the turbine during a first mode of the compressing device, receives a second energy derived from the first medium being expanded across the turbine during a second mode of the compressing device, and compresses the second medium in accordance with the first mode or the second mode. The motor provides a supplementary energy to the compressor

An airplane is provided. The airplane includes a compressing device including a turbine and a compressor. The turbine includes first and second inlets and provides energy by expanding one or more mediums. The first inlet is receives a first medium of the one or more mediums. The second inlet receives a second medium of the one or more mediums. The compressor receives a first energy derived from the first and second mediums being expanded across the turbine during a first mode of the compressing device, receives a second energy derived from the first medium being expanded across the turbine during a second mode of the compressing device, and compresses the second medium in accordance with the first mode or the second mode.

An airplane is provided. The airplane includes a first medium at a first pressure, a second medium at a second pressure, a third medium at a third pressure; and an air conditioning system. The air conditioning system includes a compressor, a first heat exchanger configured to transfer heat from the first medium to the third medium, a second heat exchanger configured to reject heat from the first medium, a third heat exchanger configured to reject heat from the second medium, a first turbine configured to receive the first medium, and a second turbine configured to receive the second medium.

An air cycle machine is provided. The air cycle machine can be included an environmental control system of an aircraft. The air cycle machine can include a turbine comprising a plurality of inlet gas flow paths, a compressor driven by the turbine from a shaft, and a fan driven by the turbine from the shaft.

An airplane is provided. The airplane includes a pressurized medium, a turbine, and a valve. The turbine includes at least one nozzle. The valve is located upstream of the turbine. The valve provides the pressurized medium to the at least one nozzle of the turbine according to an operational mode.