Heat Transfer from Immersed Slender Bodies

Abstract

This article describes a simple, low-cost experiment which could be used as a good educational example for students, combining the effects of radiation, natural convection, forced convection and condensation into one experiment. Many correlations are available for the calculation of the heat transfer from single, slender bodies (or tubes) immersed in a moving fluid. Even for a simple cylindrical tube the predicted heat transfer coefficients differ significantly from correlation to correlation. For more complex tube geometries fewer correlations could be found in the literature. The correlation by Gnielinski [1] appeared the most favourable since this single correlation is valid for many tube geometries (not just for cylindrical tubes). A simple experimental technique is described to measure the heat transfer coefficient on the outside of various tubular profiles in a fluid stream. This technique was then used to evaluate heat transfer coefficients on six different tubes, ranging from a circular cylinder to a complex T-shaped tube. The experimental data for all six tubes showed very good agreement with the correlation of Gnielinski.