INVESTIGATION OF NATURAL CONVECTION IN VERTICAL CHANNELS BY SCHLIEREN AND HOLOGRAPHIC INTERFEROMETRY (original) (raw)

Heat transfer phenomena, which frequently involve convection, are usually described through a convective heat transfer coefficient h. To obtain a precise measurement of h can be difficult, since calculation requires knowledge of the temperature gradient between the solid surface and the fluid, measured, possibly, without disturbing the thermal layer. Optical techniques are powerful tools in experimental analysis because of their non disturbing nature. In this work the natural convection heat transfer in vertical channels is investigated by applying two different optical techniques, namely schlieren and holographic interferometry. Experiments were conducted at DITEC, University of Genova (Italy) and at the Energetic Dept. of the University of L'Aquila (Italy) on the same test section. The obtained results are discussed and compared.