DESIGN, MODELING, AND TESTING OF A NOVEL ELASTOHYDRODYNAMIC SEAL FOR SUPERCRITICAL CO2 POWER CYCLES

Abstract

Effective sealing is a critical challenge in achieving the full potential of supercritical carbon dioxide (sCO2) power generation. Leakages from sCO2 cycles can reduce efficiency by up to 0.65%, underscoring the need for advanced sealing solutions. This study explores an elastohydrodynamic (EHD) seal as a promising option, designed to minimize leakage and wear under sCO2 conditions. A fluid-solid coupling model, based on finite element analysis and computational fluid dynamics, was developed and experimentally validated. Proof-of-concept tests were conducted on a 2-inch static shaft seal with pressures up to 1.2 MPa, using PTFE as the seal material. Both simulations and experiments revealed a quadratic leakage trend: leakage initially increased with pressure, peaked at about 6 g/s, and then declined to approximately 1.5 g/s at maximum pressure. The model proved efficient, converging in just 2 seconds, while providing insights into leakage rates, seal deformation, clearance pressure, and stress. In addition, a modified model was provided, which converged in less than 20 seconds with added accuracy. A parametric analysis further demonstrated the impact of key design factors on leakage, with results aligning with physical expectations. The proposed models could serve as a valuable design tool for EHD seals.