The efficiency of fluid separation processes can be enhanced by the application of sandwich packings (SPs). They consist of two alternating layers of industrially available standard packings with different specific surface areas, one with lower (the so-called holdup layer, HL) and another with higher (the so-called de-entrainment layer, DL) capacity. SPs are typically used at operating conditions between the flooding points of HL and DL. Above the HL, a froth sub-layer is formed, which reveals high separation efficiency due to intensified phase contact. In a collaborative project, the effects of the individual flow regimes on fluid dynamics and mass transfer are being investigated, both experimentally and theoretically. In order to identify the impact of the individual flow regimes, experiments in an absorption/desorption plant are supplemented by flow imaging measurements. This paper focuses on a rate-based model, in which the heterogeneous flow patterns in SPs are considered via appropriate correlations. In order to validate this model, we measured CO2 absorption characteristics under the influence of different operating and design parameters and compared them with the simulation results.