A two-dimensional two-fluid numerical model is developed for the prediction of two-phase flow thermal-hydraulics on the shell side of the kettle reboiler. The two-phase flow around tubes in the bundle is modeled with the porous media approach. A closure law for the vapour-liquid interfacial friction is based on modified pipe two-phase flow correlations. The tube bundle flow resistance is calculated by applying to each phase stream the correlations for the pressure drop in a single phase flow across tube bundles and by taking into account the separate contribution of each phase to the total pressure drop. Physically based boundary conditions for the velocity field at the two-phase mixture swell level are stated. The system of governing equations is solved numerically with the finite volume approach for two-phase flow built in the commercial computer program. Simulations are performed for available conditions of performed physical experiments. In comparison to the previous kettle reboiler two-dimensional modeling approaches, here presented model is original regarding the applied closure laws for the interfacial friction and bundle flow resistance, as well as applied boundary conditions for the modeling of two-phase mixture free surface. Also, regarding the previous published results, here obtained numerical results are compared with the available measured data of void fraction within the tube bundle and acceptable agreement is shown. (c) 2005 Elsevier Ltd. All rights reserved.