Natural convection air cooling of electronic components in partially open compact horizontal enclosures

Experimental flow visualizations and temperature measurements are conducted to investigate the passive air cooling of electronic components in partially open horizontal enclosures. A discrete flush type heat source, centrally mounted on a horizontal substrate is placed in a compact enclosure of size 127 mm/spl times/127 mm/spl times/41.3 mm (height). Computations of combined convection, conduction and radiation are used to derive the convective heat transfer data. Pronounced effects of power levels, opening sizes, enclosure aspect ratios and opening configurations and their interactions are found on the thermal performance of the discrete component using design of experiments. Time dependent flow and temperature in the air, and onset of natural convection are observed in horizontal enclosures with a single opening on the top wall. Convective heat transfer coefficients are obtained which provide guidance for thermal design of compact horizontal enclosures.