ISSN Online: 2377-424X
ISBN Print: 0-89116-130-9
International Heat Transfer Conference 6
AN INTERFEROMETRIC STUDY OF THE LOCAL HEAT TRANSFER BY NATURAL CONVECTION IN INCLINED AIRFILLED ENCLOSURES
Sinopsis
A number of relations for the natural convective
heat transfer in inclined airfilled enclosures are
known. However there is some discrepancy between
these relations with respect to the angle dependence
and the Ra dependence. Furthermore there is little
insight in the contribution of the side wall regions
to the heat transfer. Measurements of the local
heat transfer are hardly available.
In this investigation we measured the local heat
transfer using a holographic interferometer. An
enclosure with isotherm hot and cold walls and
adiabatic side walls was used. The air layer was
heated from below. Ra was varied from 104−4.106 and
the angle of inclination from 0°−90°. By integrating
Nux along the hot plate Nu was computed. The
inacuracy in Nux is 5% and in Nu 2%.
From our experiments it appeared that for ø>40° Nux
shows a maximum at the lower side of the hot plate
and a minimum at the upper side of the hot plate.
This maximum decreases with decreasing Ñ„ while the
minimum increases with decreasing ø. For ø<30° Nux
shows several maxima and minima along the hot plate.
The resulting Nu increases with decreasing ø. At
low Ra number Nu is in good agreement with
literature. At high Ra number there is some
deviation with literature. Nu-Ra relations are
given for different angle of inclination, valid for
105 < Ra <4.106.