General prediction models for void fraction and specific surface area of gas-liquid microflows

The flow characteristics of void fraction and specific surface area are important to predict the mass transfer and reaction performances in gas-liquid microreactors. However, the models and trends for the two parameters in different flow patterns remain ununified and insufficient. Accordingly, this work first time studies the void fraction and specific surface area in a very wide flow pattern range (Taylor, short bubble, bubbly, and bubble swarm flow). The results show that at the same gas-liquid flow rates, the void fraction decreases with bubble size in Taylor and short bubble flow but is totally opposite in bubbly and bubble swarm flow. Importantly, the variation of specific surface area with bubble size is independent of the flow pattern and decreases with bubble size. Finally, based on bubble size, two general models for the two parameters are developed. This work provides a new direction for the unification of flow characteristics.