A simplified linear coupled heat and mass transfer model for counter-flow absorbers is validated by comparing its predictions with those of a numerical turbulent flow model. The simplified model]ends itself to the formulation of a mass transfer effectiveness and a heat transfer effectiveness for counter-flow absorbers. The effectiveness is relatively insensitive to variations in the operating conditions of the absorber and depends mainly on the number of transfer units (NTU) and the capacity ratio. Available experimental data on a vertical tube absorber are analyzed using the simplified model to obtain heat and mass transfer correlations. (c) 2006 Elsevier Ltd. All rights reserved.