An array of electronic chips is mounted within a sealed rectangular enclosure, and cooling is implemented by attaching an aluminum heat sink (k = 180 W/m ∙ K). The base of the heat sink has dimensions of w1 = w2 = 100 mm, while the 6 fins are of thickness t = 10 mm and pitch S = 18 mm. The fin length is Lf = 50 mm, and the base of the heat sink has a thickness of Lb = 10mm. If cooling is implemented by water flow through the heat sink, with U∞ = 3 m/s and T∞ = 17°C, what is the base temperature Tb of the heat sink when power dissipation by the chips is P e1ec = 1800 W? The average convection coefficient for surfaces of the fins and the exposed base may be estimated by assuming parallel flow over a flat plate. Properties of the water may be approximated as k = 0.62 W/m ∙ K, v = 7.73 x 10-7 m2/s, and Pr = 5.2.

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-S Chips Water u. T. Janirik Electronic package. Pee