Residence time is a key parameter for the cyclones accompanied by heat and mass transfer or reaction process. The mean residence time of liquid phase in a gas-liquid cyclone was studied in a cold apparatus using the hold-up method. The results showed that the liquid residence times obviously decreased with the increase of the droplets loading

and less decreased with increasing inlet gas velocity. The main reason for the less effect of inlet velocity on the liquid residence time was that the gas-liquid interfacial shear stress was far less than the gravity of liquid film. A new model was developed to estimate the mean residence time of liquid phase in the gas-liquid cyclone based on a force balance on the liquid film. The predicted residence times were in good agreement overall with the measured values. However

the predicted residence times were higher than the measured values within the liquid film Reynolds number Rel < 1200. The relationship between the model deviation and flow pattern of liquid film was discussed.