The present disclosure is directed to systems and methods generating power using supercritical CO2 in a Brayton cycle that incorporates a double-wall turboexpander that includes an inner chamber housing the turbine and an outer chamber that includes a thermal attenuator that reduces the outer chamber wall temperature of the turboexpander. An inner chamber wall separates the inner chamber and the outer chamber within the double-wall turboexpander. In supercritical CO2 applications, the double-wall turboexpander operates at elevated temperatures and elevated pressures. By maintaining the thermal attenuator the outer chamber at an elevated pressure, the differential pressure across the inner chamber wall is reduced, requiring less high-temperature alloy material in the construction of the double-wall turboexpander when compared to a conventional turboexpander. By reducing the operating temperature of the outer chamber wall, a less costly lower-temperature alloy may be used to provide structural strength to the double-wall turboexpander.
Jason C. Wikes