Thermal Performance Characterization of Dry Gas Seals in a Supercritical Carbon Dioxide Compressor

Abstract Commercially available dry gas seals (DGSs) are the seal-of-choice for shaft-end sealing locations in compressors used in the oil and gas industry and supercritical carbon dioxide (sCO2) power cycles. The DGS’s reliability is tied to how well the 2–7 µm gas/supercritical fluid film is sustained under varying pressure, thermal, and speed conditions. Recent sCO2 turbomachinery development efforts have experienced a couple of catastrophic DGS failures at the compressor shaft-end locations. A suspected root cause of these DGS failures is thermal deformations caused by the excessive windage heating expected with the supercritical CO2 working fluid when the compressor operates at high pressures and high rotational speeds. In this work, the thermal behavior of the DGS operating in a typical sCO2 compressor is investigated. Specifically, test data are presented for a specially instrumented, commercially available DGS operating in the GE-SwRI sCO2 compressor operating under various mission points. The test data show higher than expected temperatures (about 190 °C) in the cavities surrounding the DGS, which provides useful insights to turbomachinery designers for designing seal cavities. Furthermore, the measured temperatures are compared with the predictions of a steady-state thermal model of the GE-SwRI sCO2 compressor. The thermal model uses a 1D flow advection network with cavity swirl solvers, windage, and heat transfer coefficients for sCO2 flow exchanging heat with the surrounding structure. The predictions of the thermal model match reasonably well with the measured temperature data, thereby providing validation to the novel sCO2 thermal modeling assumptions.