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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

OSCILLATION-CONTROLLED HEAT-TRANSPORT TUBES (EFFECT OF TRANSITION FROM LAMINAR TO TURBULENT FLOW ON EFFECTIVE THERMAL CONDUCTIVITY)

Get access (open in a dialog) DOI: 10.1615/IHTC11.3240
pages 317-322

Resumo

The oscillation-controlled heat-transport tube is the heat transport device based on the enhanced diffusion effect produced by oscillatory flow in a channel with an axial temperature gradient. This study is an attempt to examine whether there is any limit for the heat transport rate of oscillation-controlled heat-transport devices (OC-HTDs) or not. Since the effective thermal conductivity of OC-HTDs increases with increasing the frequency and tidal displacement of oscillatory flow, the most probable mechanism limiting the heat transport rate is the transition from laminar to turbulent flow. In this study, first, the streamline of oscillatory flow in a glass tube was experimentally visualized. The visual observation indicates that the transition criterion to the conditional turbulent flow coincides well with the result of Kurzweg et al„ Next, heat transport experiments were conducted to examine the effects of the transition on the effective thermal conductivity along the tube length. Experimental results reveal that the transition does not result in a limit of the effective thermal conductivity but produces an effective thermal conductivity higher than that predicted from the analysis assuming laminar flow.