A SELF-REGULATING FACE SEAL FOR sCO2 POWER GENERATION

In this study, a novel seal is presented and assessed for its performance. Specifically, this research addresses key challenges in advancing supercritical carbon dioxide (sCO₂₎ power generation, a critical technology for next-generation nuclear energy systems. As demand for microreactors increases, compact power conversion systems under 10 MWe are essential. At these scales, turbomachinery operates at speeds exceeding 40,000 rpm, requiring high-pressure, high-temperature shaft seals for sCO₂ Brayton cycles. To enable commercial deployment, seals must withstand temperatures up to 700 °C and pressures of 4,500 psi. This study proposes a novel, self-regulating shaft seal that could be optimized for such extreme conditions. Unlike conventional clearance seals, the proposed design minimizes leakage and wear while remaining scalable and cost-effective. Inspired by air and hydrostatic bearing principles, the seal offers a tailored solution for sCO₂ turbomachinery. A simulation framework was developed to evaluate seal performance under varying pressure differentials. Results reveal a non-linear leakage trend: leakage increases quadratically with pressure up to 53 g/s at 4.3 MPa, then decreases to 3 g/s at 9 MPa. This behavior contrasts with traditional seals, where leakage typically increases linearly with pressure, which is a disadvantage at high operating pressures. Given the potential for sCO₂ power cycles to improve thermal efficiency and reduce greenhouse gas emissions, the proposed seal design represents a promising step toward realizing the full potential of this transformative energy technology.