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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Experimental Analysis of Gas Forced Convective Heat Transfer in Microtubes under H and T Thermal Boundary Conditions

Get access (open in a dialog) DOI: 10.1615/IHTC15.fcv.009745
pages 3103-3114

Resumo

This paper focuses on the experimental analysis of convective heat transfer characteristics of pressure-driven gaseous flows through microtubes, which is frequently encountered in practical application of microfluidic devices accommodating flow, heat transfer and/or chemical reactions at micro scale. The present work has been carried out with the objectives to: (i) experimentally verify the applicability of conventional theory for the prediction of the internal forced convection heat transfer coefficient for tubes having an inner diameter lower than 1 mm and (ii) check the performance of some specific correlations proposed for the analysis of forced microconvection with gases in the last decades. Single commercial stainless steel microtubes are tested having an inner diameter between 0.17 and 1 mm. The most common thermal boundary conditions, namely uniform heat flux (H boundary condition) and uniform wall temperature (T boundary condition), have been experimentally obtained by applying Joule heating on the external surface of the microtubes (H b.c.) and by immerging the microtube in water with a fixed temperature by means of a thermostatic bath (T b.c.). The design of the test section has been made with care in order to ensure the appropriate experiment reliability and to improve the accuracy of microconvective tests at microscale. Experimental tests have been performed in both laminar and transitional flow regimes, with Reynolds number between 400 and 4000. The values of Nusselt number are experimentally determined and compared with both conventional theory and the prediction of the specific correlations developed for microchannels.