Convective Heat Transfer Coefficients in Concentric Annuli

Abstract

The geometric shape of a passage's cross-section has an effect on its convective heat transfer capabilities. For concentric annuli, the diameter ratio of the annular space plays an important role. The purpose of this study was to determine to what extent research has been done on convective heat transfer in smooth concentric annuli and, if possible, to improve on or contribute to existing theories. It was found that although various correlations exist, they are not in good agreement. For this study, experiments were conducted with a wide range of annular diameter ratios. The Wilson plot method was used to develop a convective heat transfer correlation for annular diameter ratios of 1.7 to 3.2. For Reynolds numbers (based on the hydraulic diameter), in the range of 4000 to 30000, the deduced correlation predicted Nusselt numbers accurately within 3% of experimental values.