Heat and Mass Transfer in Cocurrent Gas−Liquid Packed Beds. Analysis, Recommendations, and New Correlations

Abstract

Meticulous inspection of the literature has unveiled the weakness of several empirical methods for predicting the macroscopic mass- and heat-transfer characteristics relevant to gas−liquid cocurrent downflow and upflow packed-bed reactors. In response, using a wide experimental database consisting of 5279 measurements for trickle beds (downflow) and 1974 measurements for packed bubble columns (upflow), a set of reliable correlations has been recommended for the prediction of the gas−liquid interfacial area ( a gl ), the volumetric liquid- ( k l a ) and gas-side ( k g a ) mass-transfer coefficients, the wall (η e k lw ) and bed (η e k ls ) liquid−solid mass-transfer coefficients, the wall heat-transfer coefficient ( h w ), the bed effective radial thermal conductivity (λ e ), and the particle-to-fluid heat-transfer coefficient ( h p ). Some of these correlations are from the literature, and others have been developed by combining artificial neural networks and dimensional analysis. The accuracy of the proposed correlations surpasses by far the performances of the available methods sometimes by up to a 10-fold reduction in scatter. Notwithstanding the substantial reduction in scatter, these correlations have been thoroughly tested for phenomenological consistency and have been shown to restore the expected trends documented in the database.