Effect of flow diverters on free convection heat transfer from a pair of vertical arrays of isothermal cylinders

Laminar free convection heat transfer from two vertical arrays of five isothermal cylinders separated by flow diverters is studied experimentally using a Mach-Zehnder interferometer. The width of flow diverters is kept constant to two-cylinder diameters and the cylinders vertical center-to-center spacing is equal to three-cylinder diameter. Effect of the ratio of the horizontal spacing between two cylinder arrays to their diameter (Sh/D) on heat transfer from the cylinders is investigated for various Rayleigh numbers. The experiments are performed for Sh/D = 2-4, and the Rayleigh number based on the cylinder diameter ranging from 103 to 3 × 103. It is observed that for small Sh/D ratios, the flow diverters have a negative effect on the total rate of heat transfer from the arrays; while by increasing the horizontal center to center spacing, they tend to enhance the overall cooling rate of the array. Moreover, increasing Ra and Sh/D generally results in a higher average Nusselt number for each cylinder in the array.