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Corresponding Author

Mostafa, Hesham

Subject Area

Mechanical Power Engineering

Article Type

Original Study

Abstract

Heat transfer in pulsating laminar flow is experimentally investigated for the flow of drag reducing polyacrylamide dilute solutions in the annulus of a tubular heat exchanger. Drag reducing polymer solutions flow through the annulus of the tubular heat exchanger, while hot water as a heating source flows steadily through the inner pipe. Different polymer concentrations are considered; 10, 25, 50 and 100 wppm. Experiments are carried out at a flow pulsation of frequency of 1 Hz. This work covers a range of Reynolds number from Re=200 ̶ 1200. Steady and pulsating flows of drag reducing polymer solutions as well as steady and pulsating water flows are considered for the sake of comparison. The data of experimental measurements are supplied to a personal computer via a data acquisition system, for further analysis. The results of this work show that for steady laminar annular flow, it is hardly to detect any difference between Nusselt numbers of polymer solution flow and those of water flow. For the pulsating flow of drag reducing polymer solutions, a noticeable increase in Nusselt number of laminar annular flow is found compared with those of steady flow. Such increase in Nusselt number is slightly dependent on Reynolds number, such that for pulsating flow Nu α Re0.55 compared with Nu α Re0.55 for steady flow. When these results are compared with those of the pulsating low of water. a reduction in Nusselt number is found. This means that drag reducing additives dampen the influence of flow pulsation on heat transfer due to the damping of sueh local turbulent eddies produced by drag reducing additives.

Keywords

heat transfer; Drag reducing; Laminar; and Pulsating flow

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