An Experimental Investigation of the Augmentation of Tube-Side Heat Transfer in a Crossflow Heat Exchanger by Means of Strip-Type Inserts

The results of an experimental investigation of the augmentation of heat transfer in a crossflow heat exchanger by means of strip-type inserts are presented and discussed. Three kinds of strip type inserts—longitudinal strip (LS), crossed-strip (CS), and regularly interrupted strip (RIS)—are studied. Correlations for friction factor and Nusselt number are also developed. It is shown that on the basis of both constant pumping power and constant heat duty, LS-inserts perform better than CS- and RIS-inserts for tube-side Reynolds numbers above 19,000. At tube-side Reynolds numbers below 12,000, CS-inserts perform better than LS- and RIS-inserts. Furthermore, flow visualization was made for shell-side hot air and cold air flow in the plenum to advance the qualitative understanding of the physical phenomena of this type of crossflow heat exchanger.