Natural and forced convective heat transfer on slender cylinders

This paper presents an experimental study of free and forced convective heat transfer along vertical slender cylinders. The local heat transfer coefficient is determined from the measurement of the surface temperature distribution performed by quantitative infrared thermography. It is found that the convective heat transfer is strongly dependent on the cylinder curvature and misalignment with the flow. The effect of proximity of two cylinders is emphasized in the case of forced convection. Correlations are proposed for the two types of convection. It is worth noting that circumstances exist where the turbulent heat transfer in free convection can be of the same order of magnitude as for laminar forced convection. The outcome of the study demonstrates the suitability of quantitative infrared thermography to solve complex problems and to provide a deeper understanding of the heat transfer on slender cylinders.