Supercritical fluid systems

An aircraft power system comprising:

• at least one engine;
• and
• a supercritical fluid system comprising:
• a compressor;
• a turbine operably coupled to the compressor;
• a generator operably coupled to the turbine and configured to generate power;
• a primary working fluid flow path having a primary working fluid configured to pass through the compressor, a separator, the turbine, and back to the compressor;
• and
• a secondary working fluid flow path having a secondary working fluid configured to pass through the generator, the compressor, the separator, and back to the generator,
• wherein the primary working fluid and the secondary working fluid are compressed and mixed within the compressor to form a mixture of the two fluids, and
• wherein the separator is configured to separate the primary working fluid from the secondary working fluid from the mixture of the two fluids and direct the primary working fluid back to the turbine along the primary working fluid flow path and the secondary working fluid along the secondary working fluid flow path to the generator.