Natural Convection Heat Transfer of a Rectangular Block within a Vertical Enclosure

Abstract

A numerical solution of the natural convection heat transfer between two cold and hot isolated vertical plates is presented for different horizontal and vertical location ratios of an enclosure. Results show that: a) flow configurations of cold and hot plates are different; b) the increase of vertical location ratio, toward that corresponding to the enclosure middle value, is considerably diminishing the temperature differences between heating and cooling conditions; c) the effect of vertical location ratio variation is more prominent on heat transfer for cold and hot plates than that of the horizontal location ratio variation; d) the average Nusselt number, obtained from the hot isolated plate, is 20–39% larger than that of the cold plate under the same conditions when the isolated plate varies horizontally; e) for a narrow distance between the inner plate and the bounding wall, the inner plate Nusselt number is enhanced, but aside from this, the plate average Nusselt number is insensitive to the plate position; and f) different trends are found to affect heat transfer for cold and hot plates when the isolated plate varies vertically. The optimal vertical location can be found at specific Rayleigh number for the hot plate and cold plate.

ACKNOWLEDGMENT

This work was supported by the National Natural Science Foundation of China.

Xiaohui Zhang is an associate professor in the Department of Thermal Energy Engineering of Suzhou University, Suzhou, China. He received his Ph.D. in engineering thermophysics from the University of Shanghai for Science and Technology in 2005. During 1998 to 2002, he worked at the Institute of Suzhou Thermal Energy Engineering. His research interests are numerical heat transfer in fluid flow and thermal power energy systems.

Mo Yang is a professor of the Thermal Engineering Institute at the University of Shanghai for Science and Technology, Shanghai, China. He received his Ph.D. in engineering thermophysics from Xi'an Jiaotong University in 1992. From 1997 to 1998, as a co-researcher, he worked at Kyushu University in Japan. His main research interests are numerical heat transfer in fluid flow and multi-phase fluid flow.