Investigation of two-phase flow regimes in square minichannels with different mixers created using additive technologies

•The Direct Light Processing method is adapted for production of minichannels of a given size and geometry.•The method of statistic characteristic analysis using a high-speed shadow method and automatic postprocessing has been developed.•Statistical characteristic of bubbles and slugs in Taylor flow have been analyzed.•The junction angle has a significant effect on the formation of flow regimes and Taylor bubbles. In this paper, the effect of the junction angle on the Taylor flow regime characteristics was investigated. Using the Direct Light Processing method, minichannel mixers with different liquid and gas junction angles (from 30° to 150°) relative to the minichannel axis were manufactured. An experimental study of the two-phase flow formation was carried out, where Milli-Q® water was used as a working liquid, and high purity nitrogen was used as a working gas. A method of two-phase flow characteristic analysis using a high-speed shadow technique and automatic postprocessing was developed. Two-phase flow regimes were investigated in a wide range of gas and liquid flow rates. Size distribution of gas bubbles and liquid slugs and the distribution of bubble velocities were analyzed. The mechanisms of Taylor bubble formation and their characteristics, depending on the junction angle, were investigated.