Heat and mass transfer in laminar falling film absorption: A compact analytical model

Abstract

Absorption process plays a significant role in numerous industrial applications. Several analytical solutions have been proposed for the absorption process to calculate heat and mass transfer rates in falling film absorbers. However, the existing analytical solutions are either complex or do not consider the initial and boundary conditions at the entrance region and/or are not accurate enough. In this study, a new analytical solution for non-volatile absorbents is presented using the Laplace transform method by proposing a new velocity profile for falling films. Moreover, for the first time, compact relationships are proposed to calculate the heat and mass transfer rates in the falling film absorption process for four common absorber geometries, including: (i) inclined plates; (ii) tube bundles absorbers; (iii) vertical tubes; and (iv) coil type absorbers. The proposed compact relationships are validated with experimental data collected by others with reasonable accuracy. Furthermore, a parametric study is conducted to investigate the impact of input parameters on the absorption rate of falling film on an inclined plate. It is observed that the concentration of inlet solution is the most effective parameter and the solution mass flow rate has the least impact.