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

The characteristics of heat transfer and pressure drop have been experimentally studied for the fully developed concentric annular flow with transverse fins normal to the flow direction by the naphthalene sublimation technique. Correlations for calculating the heat transfer coefficient with different inner diameters D0 of the outer tube are presented. A ''characteristic Reynolds number'' has been proposed, by which the predominant role of the transverse fins can be evaluated. It has been indicated that the inner diameter D0 has much more effect on pressure drop than on heat transfer. The effect of D0 on the overall performance is also compared under the same flow velocity or flow rate. It has been found that the effect of developing flow on heat transfer is significant and should be taken into account during experiment.