Design of Cast Pin Fin Coldwalls for Air-Cooled Electronics Systems

At low to moderate Reynolds numbers, cast pin fin coldwalls provide the best performance and lowest unit cost for air-cooled electronics systems. Until recently, insufficient data existed to design coldwalls with moderate length pin fins for electronics systems. Empirical correlations for the Fanning friction factor, f = f(S/d, T/d, L/d, Re_d), and the Colburn j-factor, j = j(S/d, T/d, L/d, Re_d), were previously developed for two flow regimes with a transition Reynolds number, Re_trn, separating the two regimes. Using these correlations, the effect of configuration on the design is discussed and a design procedure is proposed. Example problems are presented for (1) a system cooled by an environmental control system, and (2) a system cooled by ambient air using a fan.