Experimental Study of Mixed Convection Heat Transfer in a Vertical Concentric Annulus Subjected to an Asymmetric Heating

Abstract

The experimental study had been conducted for a mixed convection heat transfer of water flow through a vertical concentric annulus with asymmetric uniformly heated inner and outer cylinders, and packed with a saturated metallic porous media. The experimental investigation includes a range of Ra from 47903 to 122419 for outer cylinder and for inner cylinder Ra range from 23500 to 62300 and Reynolds number range, which is based on the particles diameter of Red = 4.79, 7.91 and 9.58. Heat flux varied from 752.4 W/m2 to 1990.4 W/m2 on the inner surface, and heat flux varied from 1530.8 W/m2 to 3912.2 W/m2 on the outer surface. Under a steady state condition, the measured data were collected and analyzed. The results show that the temperature variations along the inner and outer surfaces of cylinders are affected by the imposed heat flux variation and Reynolds number variation. The local Nusselt number variation with the axial distance and mean Nusselt number are presented and analyzed. An empirical correlation has been suggested to calculate the mean Nusselt number for the geometry and boundary conditions under investigation. Also a comparison was done between the present experimental work and the results of a previous work for the mean local Nusselt number was made and gave good agreement.