A new experimental method for characterizing boiling regimes of water in vertical milli-channels

Over the past few decades, high-performance heat-transfer devices have been studied for numerous applications. Boiling flow in such confined spaces induces high-frequency instabilities that directly influence performances. A small-scale water vaporizer with 10 mm-sized channels is experimentally over a wide range of vapor quality (0.05–1). The peculiarity setup transparent window allows high speed imaging boiling up to 5 bars. This work focuses on post-processing method based spatio-temporal diagrams. Hydrodynamics can be observed diagrams enabling understand mechanisms and regimes inside channels. Four are observed, namely bubbly, slug, churn annular flow. Diagrams also used estimate local mean void fraction time channels, quality, slip ratio flow-regime map. For qualities under %, bubbly predominant channel. higher qualities, if specific mass rate below 37 kg/s/m², only slug whereas larger rates.