Investigation of the void fraction–quality correlations for two-phase hydrogen flow based on the capacitive void fraction measurement

The void fraction and vapor quality are important parameters for characterizing the gas–liquid two-phase flow. However, neither an established void fraction measurement method nor a verified void fraction – vapor quality interconversion model is available for the two-phase hydrogen flow. The object of this study is the development of a void fraction measurement technique and the investigation of the void fraction–quality correlations. A capacitive void fraction sensor was developed using the electric field analysis (EFA) and design of experiment (DOE), and it was applied in a boiling hydrogen experimental facility. The experimental conditions were as follows: the inner diameter of the heating pipe was 15 mm, the mass flux was ranged from 50 to 110 kg/m²s, and the static pressure was ranged from 250 to 300 kPaA. Further, the correlation between the thermal equilibrium quality (χ_ac=− 0.03–0.14) and void fraction (α = 0–70%) was compared with that obtained in previously proposed models, and the void fraction – actual quality – thermal equilibrium quality interconversion models applicable to the boiling hydrogen flow were investigated. It was observed that the combination of the Sekoguchi model for thermal equilibrium quality – actual quality conversion and the Steiner drift-flux model for actual quality – void fraction conversion agreed well with the experimental results.