On the estimation of the regime transition point in bubble columns

Using literature data of gas hold-up as a function of the superficial velocity from 16 different sources, a data bank of regime transition points was elaborated. It comprises 83 data related to a total of 20 systems, covering a wide range of physical properties and operating parameters, for both perforated and porous plate spargers. This data bank was employed to critically assess the quality of the predictions of the regime transition point given by available literature correlations. All correlations tested failed to provide a proper representation of the data bank, with rather high mean absolute deviations (always greater than 37%) and, in some cases, even physically inconsistent values were obtained. Thus, new empirical formulas were proposed for estimating the gas superficial velocity at the point of regime transition in bubble columns and the corresponding gas hold-up, whose mean absolute deviations were respectively equal to 17.7 and 21.1%.