Enhancing power cycle efficiency for a supercritical Brayton cycle power system using tunable supercritical gas mixtures

A method, comprising:

• sensing at least one environmental condition pertaining to a supercritical Brayton cycle power generation system by a sensor;
• receiving in a processor first data from the sensor that senses the at least one environmental condition;
• computing a first desired critical temperature of a fluid that flows through the supercritical Brayton cycle power generation system based at least in part upon the first data from the sensor;
• causing the processor to compute a first composition of the fluid such that the fluid has the first desired critical temperature and adjusting at least one parameter of the fluid by an actuator that effects a composition modifier module to add or remove compounds or additives to the fluid to obtain the first composition;
• and
• operating the Brayton cycle power generation system with the fluid of the first composition computed by the processor;
• wherein the at least one environmental condition is selected from the group consisting of ambient temperature and barometric pressure;
• and
• wherein the fluid is at supercritical temperature and pressure.

A supercritical Brayton cycle power generation system, comprising:

• compressor means for compressing a fluid having a composition that travels through the supercritical Brayton cycle power generation system;
• turbine means that receives the fluid compressed by the compressor means and rotates a shaft;
• generator means that is coupled to the shaft and generates electric power based at least in part upon rotational velocity of the shaft;
• piping means for transporting the fluid between the turbine means and the compressor means;
• and
• heat rejection means for rejecting heat in the piping means at a temperature that is within 10% of the desired supercritical temperature of the fluid;
• wherein the environmental parameter is selected from a group consisting of ambient temperature and barometric pressure;
• and
• wherein the fluid is at supercritical temperature and pressure;
• an actuator to add or remove compounds or additives to the fluid;
• a processor that sends a signal to the actuator to add or remove compounds or additives to the fluid to modify the composition of the fluid during operation based at least in part upon a desired supercritical temperature of the fluid,
• a sensor for sensing ambient temperature or barometric pressure;
• wherein the system modifies the composition to obtain the desired supercritical temperature of the fluid based at least in part upon an environmental parameter sensed by the sensor, the composition comprising CO2 and an alkane.