HEAT-TRANSFER AND PRESSURE-DROP OF A TRANSVERSELY FINNED CONCENTRIC ANNULUS WITH LONGITUDINAL FLOW

The characteristics of heat transfer and pressure drop have been exper imentally studied for the fully developed concentric annular flow with transverse fins normal to the flow direction by the naphthalene subli mation technique. Correlations for calculating the heat transfer coeff icient with different inner diameters D0 of the outer tube are present ed. A ''characteristic Reynolds number'' has been proposed, by which t he predominant role of the transverse fins can be evaluated. It has be en indicated that the inner diameter D0 has much more effect on pressu re drop than on heat transfer. The effect of D0 on the overall perform ance is also compared under the same flow velocity or flow rate. It ha s been found that the effect of developing flow on heat transfer is si gnificant and should be taken into account during experiment.