Experimental investigation on interfacial area concentration in narrow-channel steam-water flow based on printed circuit sensor

Abstract

Due to deficiency of void fraction measurement of steam-water flow in narrow channels, existing interfacial area concentration (IAC) models for narrow channels have mostly been developed based on air–water flow. The applicability of these models to steam-water flow remains uncertain. To address this deficiency, a ceramic-substrate printed circuit (CSPC) sensor is utilized to obtain the instantaneous interface topology of steam-water flow in a narrow rectangular channel. Experiments were conducted under pressures ranging from 0.2 to 0.9 MPa, covering flow patterns from bubbly to annular flow. The average bubble shape, projected interfacial area concentration (PIAC), and projected interfacial length concentration (PILC) for bubbles of different sizes were comprehensively analyzed. The critical diameter separating distorted and cap bubbles, as utilized in existing IAC models, was verified from a statistical averaging perspective. Within the experimental conditions, PIAC and PILC showed no significant variation under different pressures. The case-averaged PIAC and PILC of steam-water flow and air–water flow exhibited good agreement within the same channel geometry, although some divergence was observed for bubbles of different sizes. Among the existing IAC correlations, the Yang-Xiong model demonstrated the best performance in predicting IAC compared to the present experimental data. The relative error of the total IAC was within ± 10 % for most cases and decreased with increasing void fraction.