Cabin air compressor bypass for surge avoidance

An environmental control system for a vehicle comprising:

• a source of a first medium;
• a cabin air compressing device including a first compressor having a compressor inlet and a compressor outlet;
• a conduit fluidly coupling the source of the first medium to the compressor inlet, wherein the first medium provided to the compressor inlet is output at the compressor outlet as a compressed first medium;
• an environmental control system pack located downstream from and fluidly coupled to the compressor outlet, the environmental control system pack including a ram air circuit having at least one ram air heat exchanger and a thermodynamic device including a second compressor and a turbine operably coupled by a shaft;
• and
• another conduit for providing a second medium to the first compressor, the another conduit fluidly coupling an outlet of the at least one ram air heat exchanger and the compressor inlet;
• wherein a pressure of the second medium is greater than a pressure of the compressed first medium.