HORIZONTAL SIMULATED PRINTED-CIRCUIT BOARD ASSEMBLY IN FULLY-DEVELOPED LAMINAR-FLOW CONVECTION

Steady-state convective heat-transfer and pressure-drop characteristic s far laminar air-flows over a horizontally-orientated simulated print ed-circuit board (PCB) assembly have been measured experimentally and predicted numerically, The considered assembly consisted of a plate wi th uniformly-spaced identical electrically-heated rectangular uniform ribs mounted orthogonal to the mean air-flow. Mathematical correlation s were determined between the cavity-height to ribs' protrusion and wi dth-to-protrusion ratios, namely (H/B) and (L/B), respectively, and th e Reynolds number (Re-C) of the air-flow with the steady-state Nusselt number (Nu(C)) and friction factor (f(C)), both of these latter param eters being highly dependent on H/B. When H/B greater than or equal to 8, natural convection provided a significant portion of the total rar e of heat transfer, and mixed (i.e. forced plus natural) convection en sued. For assemblies with ribs each of the same volume, the assembly w ith the ribs having a larger top surface-area has the higher heat-tran sfer coefficient and smaller pressure drop under otherwise identical c onditions. (C) 1997 Elsevier Science Ltd.