Heat Transfer and Pressure Drop Characteristics of Segmented Finned Tube Assembly in Circumferential Layout

摘要

Heat transfer and pressure drop characteristics of finned tube bundle arranged in circumferential layout have been analysed using the general purpose CFD code Star CD. The general practice followed in the process design of the heat exchangers having this layout of finned tube bundle is to calculate the heat transfer and pressure drop coefficients based on the reported correlations for staggered layout of finned tube bundle with an approximated mean geometrical parameters of the circumferential layout applied. The CFD estimates have been compared against the coefficients calculated based on correlations. CFD estimated pressure drop and heat transfer coefficients are about 30% and 18% lower than those estimated based on the correlation with approximated geometrical parameters. Thus, the application of correlation for pressure drop calculation in the design of heat exchanger is conservative whereas the heat transfer correlations have to be applied with suitable uncertainty. Further analysis of the serrated fin configuration in the same layout shows that there is no enhancement in the pressure drop offered by this configuration over that of plain fin configuration. Enhancement possible in the heat transfer coefficient with serrated fins has been estimated to be 20% over that of plain fin configuration.