An Experimental Study Of Natural Convection Heat Transfer Through A Cavity Between Eccentric Horizontal Cylinders

Abstract

An experimental study on natural convection heat transfer across an eccentric horizontal annulus under the condition of constant surface temperature was carried out. The study included clarifying the effect of eccentricity ratio and the angular position as well as the effect of Raleigh number on the ability of the inner cylinder to heat reject. An experimental set-up was done for this purpose which consists of a cooling water tank and two aluminum cylinders, the outer diameter of the inner cylinder is(26mm), electrically heated from the inside, which represents the heating element, the inner diameter of the outer cylinder is(100mm) which represent cooling element in this set-up. The experimental study showed that the ability of the inner cylinder to transmit heat with free convection is a function to eccentricity ratio and the angular position, as well as Raleigh number, where this ability increases as angular position increases for all eccentricity ratios, while the eccentricity ratio effect depends on the angular position, where the thermal performance for the inner cylinder may be better at the location (δ=180o) for the ratio (ε=0.2), where the maximum enhancement in heat transfer coefficient was recorded as(10%) at this location in comparison with concentric annulus, whilst the location (δ=0o)for the ratio (ε=0.726) was given maximum reduction in heat transfer coefficient for the inner cylinder was recorded as (23%) in comparison with concentric annulus, whilst the coefficient of heat transfer proportional directly with Raleigh number.