An Innovative Elasto-Hydrodynamic Seal Concept for Supercritical CO₂ Power Cycles

Supercritical CO₂ (sCO₂) power cycles are promising next generation power technologies, holding a 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 sCO₂ temperatures and pressures of 350–700 °C and 20–30 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 the next generation nuclear turbine and compressor development. In this study, we propose a novel Elasto-Hydrodynamic (EHD) high-pressure, high temperature, and scalable shaft seal for sCO₂ turbomachinery that offers low leakage, minimal wear, low cost, and no stress concentration. The focus in this paper was to conduct a proof-of-concept study with the help of physics-based computer simulations. The results showed that the proof-of-concept study was successfully demonstrated, warranting further investigation. Particularly, it was interesting to note the quadratic form of the leakage rate, making its peak of $m˙$ = 0.075 kg/s at P_in = 15 MPa and then decaying to less than $m˙$ = 0.040 kg/s at P_in = 30 MPa, suggesting that the proposed seal design could be tailored further to become a potential candidate for the shaft seal problems in sCO₂ turbomachinery.