The effects of particle properties, void fraction, and surface tension on the trickle-bubbly flow regime transition in trickle bed reactors

•Trickle-bubbly flow regime transition depends strongly on void fraction, particle shape, and surface tension.•Transition was observed to be relatively independent of gas velocity for all cases.•Applicability of extending existing models for the trickle-pulsing transition is reviewed.•Correlation developed in this work provides accurate prediction of experimental results.