Elasto-Hydrodynamic Seal for sCO2 Applications

Supercritical CO2 (sCO2) power cycles are superior over traditional water based, air-breathing, direct-fired, open Brayton cycles or indirect-fired, closed Rankine cycles in terms of efficiency and equipment size. They hold great potential in fossil fuel power plants, nuclear power production, solar power, geothermal power, and ship propulsion. To unlock the potential of sCO2 power cycles, technology readiness must be demonstrated on the scale of 10 – 600 MWe and at sCO2temperatures and pressures of 350 – 700 ºC and 20 – 35 MPa for nuclear industries. Amongst many challenges at the component level, the lack of suitable shaft seals for sCO2 operating conditions needs to be addressed for DOE’s next generation nuclear turbine and compressor development. We propose a proprietary Elasto-Hydrodynamic (EHD) high-pressure, high temperature, and scalable shaft seal for sCO2 turbomachinery in this STTR Phase I. The EHD seal for aircraft engine sealing has the following benefits to the sCO2 turbomachinery: Low Leakage. The self-regulated minimum clearance throttles the sCO2 leaking flow and improves cycle efficiency. Minimum Wear. The primary EHD seal operates on non-contact conditions. The startup seal only contacts the rotor at the startup and disengages from the rotor after startup. Smoother and Faster Startup. Unlike clearance-type seals, the startup seal addition provides a smooth transition from cold start to operation condition. Low Cost. Simple structure results in low seal cost and minimal wear saves maintenance cost. No Stress Concentration. EHD seal design eliminates sharp angle and stress concentration. In this STTR Ultool will conduct the development of the EHD seal for sCO2 turbomachinery, which will advance sCO2 seal TRL for support DOE sCO2 Power Cycle Program. Phase I will establish the boundaries and opportunities of the proposed EHD seal for sCO2 turbomachinery; prove the feasibility of sCO2 EHD seal through tests; and prepare the design criteria to be implemented in the Phase II prototype and beyond for full-scale commercialization.