Modeling of a Novel Elastohydrodynamic Seal for sCO2 Power Cycles With Experimental Verification

Abstract Effective sealing remains to be one of the technological challenges at the subcomponent level for supercritical carbon dioxide (sCO2) power generation to be practical. Leakages from sCO2 power cycles can lower cycle efficiencies by up to 0.65%. Therefore, to fully harness the benefits of sCO2 power generation; this leakage must be addressed through engineering of efficient sealing technology. To this end, we propose an elastohydrodynamic (EHD) seal as a potentially effective solution that can operate at sCO2 conditions with minimal leakage and wear. In this study, an FEA/CFD based fluid-solid coupling modeling approach was presented with experimental verification. For proof-of-concept purposes, the tests were performed on a 2” static shaft seal and with pressures up to 1.2 MPa using PTFE as the seal material. Both the test and simulation results exhibited a quadratic leakage trend. The leakage rate first increased with increasing pressures, then made its peak of about 6 g/s in mid-pressure range, then started to drop to lower values of about 1.5 g/s as the pressure reached the maximum operating pressure. The proposed model was demonstrated to be a quick and handy tool to determine the design space of the EHD seals with minimal computational time. The simulation was converged in only 2 s. Yet, the proposed model could provide data regarding the leakage rate, seal deformation, pressure in the clearance, and stress on the seal, and thus, could serve as a design guide for the EHD seals.