Characterization of hydrodynamic regimes in a bubble column

An experimental technique is developed to characterize the hydrodynamic regimes of a bubble column. This involves measurement and statistical analysis of temperature-history records of an element of the heat transfer surface immersed in the bubble column as a function of gas velocity. The data are taken in a 0.108m diameter bubble column for the nitrogen-water and nitrogen-Therminol systems at ambient conditions. The statistical functions computed at each gas velocity are the variance, autocorrelation function (acf), and the power spectral density function (psdf). The variations of variance and a mean frequency defined for the power spectral density data with gas velocity are found to characteristically represent the discrete bubbling, transitional and churn-turbulent regimes. It is shown that the experimentally observed characteristic variation of the overall heat transfer coefficient of an immersed surface in bubble column with gas velocity are in qualitative accord with the inferred hydrodynamic regime delineation information.