Work Problem 7.29, taking into account the increase in temperature of the water as it flows through the heat sink. Properties of water are listed in Problem 7.29, along with p = 995 kg/m³ and c_p = 4178 J/kg · K.

Data From  Problem 7.29

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 L_f = 50 mm, and the base of the heat sink has a thickness of L_b =10 mm.

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 T_b of the heat sink when power dissipation by the chips is P_elec = 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, p = 995 kg/m³, c_p = 4178 J/kg ·
K, v = 7.73 10^–7 m²/s, and Pr = 5.2.

Transcribed Image Text:

Lf Electronic package, Pelec THE Water To - S -Tb Chips