An investigation of the performance of compact heat exchangers for latent heat recovery from exhaust flue gases

An experimental and theoretical investigation of the utilization of finned tube compactheatexchanger for a heatrecovery steam generator (HRSG) to recover both sensible and latentheat is presented in this paper. The heat transfer and pressure drop characteristics of the fin-and-tube heatexchanger are theoretically studied. A correlation of the combined convection–condensation heat transfer is derived by using the heat and mass transfer analogy models. The experimental results have shown that the Colburn factor (j) and the friction factor (f) for humid air, simulating the exhaust of HRSG, are larger than those for dry air. It has been also found that the f factor difference between humid air and dry air decreases as the air side Reynolds number increases and both the f factor and the j factor for humid air increase with the increase of water vapour concentration. A scheme for the design of compactheatexchanger for HRSGs is presented.