Experimental Study of Laminar Natural Convection Heat Transfer from Slender Circular Cylinder in Air Quiescent Medium

Abstract

In this paper, variation of local heat transfer coefficient from the surface of cylindrical heat source both in vertical as well as horizontal configuration has been determined through experimentation. Fourteen experiments were performed in an air quiescent medium in the laminar range to completely expedite the problem. Each experiment was repeated thrice to calculate precision of the data under steady state condition. This study includes the designing and manufacturing of heat sources, calibration of sensors, installation of thermocouples to measure surface temperature and obtaining of experimental results in the form of local dimensionless numbers. For experimentation, aluminum cylindrical heat source having 5.1 cm diameter and 31 cm lengths was employed. During experimentation, convective heat flux was varied from 9.39 w⁄m−2 to 638.99 w ⁄m−2 and maximum recorded temperature difference was 87.24 K for vertical heat source configuration and 116.49 K for horizontal configuration. Study shows that for vertical heat source configuration, local Nusselt number decreases from bottom to certain height and then increases; this is due to end losses. While in horizontal configuration of heat source, local Nusselt number is found maximum at the bottom and minimum at the top of the heat source. At the end, results were compared with the published data and were found satisfactory.