NATURAL CONVECTION OF AN ISOLATED PLATE IN RECTANGULAR ENCLOSURES

摘要

The heat transfer of an isolated plate in rectangular and trapezoid enclosure was investigated by numerical methods. It is shown that the size and shape of enclosure have effect on the heat transfer of the plate. At a given width, the Nusselt number increases with the height increases for large Rayleigh number. At a given height the Nusselt number decreases first and then increases with the increasing of the width, there is a width corresponding to a smallest Nusselt number for a small Rayleigh number. But for big Rayleigh numbers, the Nusselt numbers increase first and then decrease slowly, there is a width corresponding peak value. It shows that for low Rayleigh number cases, increasing the enclosure width may decrease the heat transfer of the plate. With a slope ceiling, the heat transfer may be enhanced about 10% compared to the rectangular enclosure.