Chimney effect on natural air cooling of electronic equipment under inclination

Natural air-cooling needs neither a fan nor a blower. However, cooling capability of natural air-cooling is low, so the improvement of its capability is indispensable. In this study, the system box is inclined for the purpose to raise the capability of natural air-cooling, and the increase in natural circulation flux in the box is quantitatively proven by experiments. The case studies used three models of notebook PC that have two kinds of heat sources. The box was inclined 0 to 90 degrees up from the horizontal plane. The influence by the box inclination, the box dimensions, and the heating element size was investigated. Moreover, the experimental data were reduced to a Nusselt number - Rayleigh number correlation that does not include explicitly the box dimensions, the heat source size, and the inclination angle.