This paper presents experimental results on convective heat transfer of air flows over a not-thin aluminum plate with transverse, straight ribs for different pitch-to-rib-side ratio values. Data over a flat plate are also reported for comparisons. The plate is 200 mm long and 150 mm wide, and it is heated by a thin foil heater; ribs have a square cross-section of 3-mm side. The paper first reviews the experimental setup and the data processing to recover heat transfer characteristics from IR-thermographic images; then, thermal performances of tested configurations, namely, pitch-to-rib-side ratio ranging from 10 to 40, are presented and discussed. Air flows at room temperature with speed from 2.3 to 11.6 m/s, corresponding to Reynolds numbers at the end of the heated-length between 50000 and 250000, and for a heat flux of near 550 W/m2. For the considered ribbed surfaces, the average Nusselt number shows an increase with respect to the flat plate varying from 45 to 130% as Re increases but with slight differences between them.

EXPERIMENTAL RESULTS BY IR-THERMOGRAPHY ON CONVECTIVE HEAT TRANSFER OVER ENHANCED SURFACES

FUSTINONI, DAMIANO;GRAMAZIO, PASQUALINO;NIRO, ALFONSO
2011

Abstract

This paper presents experimental results on convective heat transfer of air flows over a not-thin aluminum plate with transverse, straight ribs for different pitch-to-rib-side ratio values. Data over a flat plate are also reported for comparisons. The plate is 200 mm long and 150 mm wide, and it is heated by a thin foil heater; ribs have a square cross-section of 3-mm side. The paper first reviews the experimental setup and the data processing to recover heat transfer characteristics from IR-thermographic images; then, thermal performances of tested configurations, namely, pitch-to-rib-side ratio ranging from 10 to 40, are presented and discussed. Air flows at room temperature with speed from 2.3 to 11.6 m/s, corresponding to Reynolds numbers at the end of the heated-length between 50000 and 250000, and for a heat flux of near 550 W/m2. For the considered ribbed surfaces, the average Nusselt number shows an increase with respect to the flat plate varying from 45 to 130% as Re increases but with slight differences between them.
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9788846730725
Enhanced heat transfer; ribbed surfaces; IR thermography
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/608772
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