The contemporary gas turbine engine, developed in the 1940’s by Sir Frank Whittle (pictured), is still considered to be among the most efficient, external combustion engines. Today, there is a resurgent interest in power generation technology driven by humankind’s insatiable need for more power. A popular focus is to extend the Brayton Cycle, the thermodynamic basis for a gas turbine engine, to using CO2 in a closed Brayton Cycle. This is commonly referred to as a Supercritical CO2 (sCO2) system. As the name implies, the CO2 is at pressures above the critical point of CO2 or 1,070 psia. The highest pressure in the cycle can often be designed to be 4 times this pressure and operate at temperatures as high as 700°C at the inlet to the turbine.