V‐shaped pressure drop curve of microbubble swarm flow in a microchannel

Abstract Precise prediction of the pressure drop in a gas–liquid microreactor is significant for reactor design; however, the understanding on the pressure drop in the microbubble swarm flow in microreactors is limited. Accordingly, this is the first study in which the rules for the pressure drop in the microbubble swarm flow over a wide range of void fractions are investigated. At a given gas flow rate, the pressure drop first decreases with the liquid flow rate and then gradually increases and almost occurs at a void fraction of 0.20; this is named as the V‐shaped pressure drop curve of microbubble swarm flow. In addition, the microbubble size, specific surface area, and void fraction are tested to reveal the mechanism underlying this new phenomenon. Finally, the two regions of separated and homogeneous flows are divided, and semi‐empirical prediction models are developed to quantify the pressure drop in the microbubble swarm flow.