Heat transfer coefficients in concentric annuli

Abstract

Paper presented to the 1st International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Kruger Park 8-10 April 2002.The geometric shape of a passage's cross-section has an effect on its convective heat transfer capabilities. For concentric annuli, as cross section, the diameter ratio of the annular space plays an important role. The purpose of this investigation was to find a correlation that will accurately predict heat transfer coefficients at the inner wall of smooth concentric annuli for the flow of water. Experiments were conducted on water under turbulent flow conditions for a wide range of diameter ratios. The Wilson plot method was used to determine the heat transfer coefficients from which a correlation was developed that could be used to predict the heat transfer coefficients. It was found that the correlation predicted Nusselt numbers accurately within 3% of measured values for diameter ratios between a= 1.7 and a= 5.1 and a Reynolds numbers range of 4 000 to 30 000.