Free convection from a constant heat flux elliptic tube

An experimental investigation is presented on free convection of air around the outer surface of a constant heat flux elliptic tube. The local and average Nusselt number distribution is reported for different. values of Rayleigh number and different tube inclination angles. The test Rayleigh number, based on input heat flux, ranges from 1.1 x 10(7) to 8 x 10(7). Average Nusselt numbers are evaluated and correlated with Rayleigh number for the elliptic tube with vertical major axis. Comparison between the convection characteristics of isothermal and constant heat flux elliptic tubes has been presented. Also, the effect of elliptic tube orientation on the average Nusselt number is shown. It is found that a higher value of average Nusselt number is achieved when the major axis of the tube is vertical. (C) 2002 Elsevier Science Ltd. All rights reserved.