Aircraft environmental control system

An environmental control system of an aircraft comprising:

• a plurality of inlets for receiving a plurality of mediums including a first medium and a second medium;
• an outlet for delivering a conditioned form of the second medium to at least one load of the aircraft;
• a ram air circuit including a ram air shell having at least one heat exchanger positioned therein;
• a dehumidification system arranged in fluid communication with the ram air circuit;
• and
• a compression device arranged in fluid communication with the ram air circuit and the dehumidification system, the compression device including a compressor and a plurality of turbines including a first turbine and a second turbine operably coupled by a shaft, wherein an outlet of the first turbine is directly coupled to an inlet of the second turbine, such that the first medium is provided to the first turbine and the second turbine in series and an outlet of the second turbine is fluidly coupled to the ram air circuit such that the first medium output from the second turbine is exhausted into the ram air circuit.