Improved liquid hold-up correlation for randomly packed towers

The state-of-the-art tools for the evaluation of the total liquid holdup in gas-liquid counter-current randomly dumped packed beds are critically eval uated by thoroughly interrogating a wide hydrodynamic database. This databa se, consisting of ca. 1,500 experiments on liquid hold-up below the floodin g point, represents an important portion of the non-proprietary information released in the literature since the 1930s. Providing access to diversifie d information, it is dedicated to embracing wide-ranging temperature and ga s density levels, and packing shapes extending from classical ones to moder n third generation packings. Furthermore, a total of eleven correlations on the total liquid hold-up extracted from the literature are cross-examined using the database. Many limitations regarding the level of accuracy and ge neralization come to light with this investigation. Artificial neural netwo rk modelling and dimensional analysis are then proposed to improve the accu racy in predicting the total liquid hold-up in the pre-loading and the load ing regions of packed beds. A combination of five dimensionless groups, com prising the liquid Reynolds (Re,), Froude (Fr,), and Ohnesorge (Oh,) number s as well as the gas Froude (Fr,) and Stokes (Sr,) numbers are used as the basis of the correlation. The correlation yields an absolute average relati ve error of ca. 14% for the whole database and remains in accordance with t rends reported in the Literature.