Flow-induced oscillation of membrane tapes and its effect on heat transfer of a transitional pipe flow

Abstract

Flow-induced oscillation is an effective way for heat transfer enhancement, which embraces the advantages of requiring no extra energy consumption and better performance for preventing fouling or soot formation. In the present study, a thin membrane tape with length, width and thickness of 90 mm, 3.8 mm and 13.3 um respectively was mounted inside a horizontal pipe with an internal diameter of 13 mm. By visual measurement, the tape was demonstrated to be able to oscillate within airflow and the oscillation frequency was found to increase with the flow rate. Constant heat flux was applied at the pipe wall through electrical heating and the wall temperature was obtained by thermocouples. In low Reynolds number turbulent region (Re between 1800 and 4200), the mean heat transfer coefficient and flow resistance were found to be 1.3-1.7 times and 1.6-2.1 times than that of a smooth tube, respectively. However, the heat transfer enhancement effect is most pronounced at lower Re and as the Re increases, this effect becomes weak. Nevertheless, the spontaneous oscillating tapes can be a very promising heat transfer intensification element. This study is a primary investigation attempt and flow-induced oscillations of membrane tapes of different dimensions and the use of multiple membrane tapes are awaited to be studied deeply.