A mathematical model of forced convection condensation of steam on smooth horizontal tubes and tube bundles in the presence of noncondensables

Abstract

This paper presents a description and the results of verification of an unsteady model for forced convection condensation on a smooth single horizontal tube in the presence of noncondensables. The external flow is described by the two-dimensional (2D) unsteady Navier–Stokes equations for a laminar regime or by the unsteady Reynolds-averaged Navier–Stokes (URANS) equations for a turbulent regime, and the condensate film is considered using a one-dimensional model. Details of the numerical implementation of the developed algorithm are described. The available literature data were employed to verify the proposed model for forced convection condensation for an arbitrary flow direction of vapour with and without noncondensables. The numerical results are in good agreement with the published experimental data. In the proposed model, condensation influences the air-vapour mixture flow only through the boundary condition; therefore, this model can be easily implemented using different computational fluid dynamics (CFD) codes (in this work, an “in-house” CFD code ANES) for modelling more complex configurations, like tube bundles. Results for condensation on five tubes in a tube bundle are also presented in this work. The influence of mutual irrigation of pipes by drops coming off was also approximated.