Chimney Effect on Natural Air Cooling of Electronic Equipment Under Inclination

Abstract

With the rapid increase of the power dissipation density in modern electronic equipment, the cooling design of electronic equipment becomes increasingly important. For widely used forced-convection air-cooled systems, the reliability of and the acoustic noise of the fan present serious concerns as the air velocity is increased to enhance the cooling capacity. Thus, the interest in natural-convection air cooling is growing to take advantage of low noise and energy savings inherent in that cooling mode. One method of promoting the capacity of natural air cooling is to incline the electronics casing, thereby, induce draft air by what is called the chimney effect. However, the effect of inclination on thermal behavior and cooling capacity has not yet been fully understood due to the involvement of many parameters in driving the draft air. This paper presents the results of experimental and numerical studies on the effect of casing inclination on the temperature rise across the casing. The numerical simulation was implemented to find out the thermal behavior inside a thin electronic casing. The simulation results are in good agreement with the experiment data. A thermal design guide is obtained regarding how the cooling effect is improved by increasing the inclination angle.