Experimental study of natural convective heat transfer from an inclined isothermal cylinder with an exposed top surface mounted on a flat adiabatic base

Abstract

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.

Natural convective heat transfer rates from inclined cylinders with a circular cross-section and which have an exposed top surface have been experimentally measured. The cylinder is mounted on a large flat essentially adiabatic surface with the other cylinder surfaces exposed to the surrounding air and with the cylinder, in general, inclined to the vertical at angles between vertically upwards and vertically downwards. The diameter-to-height ratio of the cylinders used in the present study was comparatively small, diameter-to-height ratios of between 1 and 0.25 being used. The main aim of the present work was to determine how the diameter-to-height ratio of the cylinder, i.e., D/h, influences the mean heat transfer rate from the cylinder at various angles of inclination. The heat transfer rates were determined by a transient method, which basically involving heating the model and then measuring its temperature-time variation while it cooled. Tests were carried out in air with all models at various angles of inclination to the vertical of between 0o and 180o. The Rayleigh number, Ra, based on the cylinder height, h, was between approximately 2E4 and 4E6. The experimental results have been compared with the results obtained in an earlier numerical study.