Modeling of conjugate conduction and heat and mass convection in tube-fin exchangers

Purpose - The purpose of this paper is to examine the modeling of simultaneous heat and mass transfer under dehumidifying conditions. Moist air cooling in tube-fin exchangers is investigated using a finite element technique. Design/methodology/approach - The model requires the solution of a conjugate problem, since interface temperatures must be calculated at the same time as temperature distributions in adjacent fluid and solid regions. The energy equation is solved in the whole domain, including the solid region, and the latent heat flux on the surfaces where condensation takes place is taken into account by means of an additional internal boundary condition. Findings - Thermal performances for different Reynolds numbers of a typical two-row tube-fin exchanger are numerically analysed, for both in-line and staggered arrangements of tubes. The results justify the great importance that the ratio between latent and overall rates of heat transfer has in the design of compact heat exchangers. Practical implications - In this work, the capabilities of the proposed methodology to deal with industrial applications in the field of compact exchangers are outlined. Originality/value - The paper presents an effective approach to the solution of conjugate conduction and convection problems with simultaneous heat and mass transfer. The formulation is completely general, even if the finite element method is used in the calculations.