Turbulent heat transfer and flow characteristics in a horizontal circular tube with strip-type inserts. Part I. Fluid mechanics

This paper is the first of two papers that present the result of a study of turbulent flow and pressure drop in a horizontal tube with strip type inserts. Experimental data taken for air for a class of strip type inserts (longitudinal, LS and cross, CS inserts) used as a tube side heat transfer augmentative device for a singlephase cooling mode operation are presented. To broaden the understanding of the underlying physical phenomena responsible for the heat transfer enhancement, flow mechanisms through velocity measurements are combined with pressure drop measurements to develop friction factor correlations for 6500<=Re<=19 500 where Re is the Reynolds number. Friction factor increases were typically between 1.1 and 1.5 from low Re(~=6500) to high Re(~=19 500) with respect to bare tubes.