Experimental study on free convective heat transfer from vertical square ducts

In this paper the effect of free convection heat transfer around vertical square ducts has been studied experimentally. Inconel heating element is used to heat the duct from the center and thermocouples are mounted on each side to measure circumferential average temperature. Experiments were conducted under constant heat flux conditions. Two ducts are considered with variable side length to study the effect of area ratio. Wide range of experiments are conducted to investigate natural convection in laminar and transition regions. Regression analysis is performed and new correlations were proposed in terms of local and average non-dimensional numbers.