The heat sink of 7.29 is considered for an application in

Chapter , Problem 11.91

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The heat sink of 7.29 is considered for an application in which the power dissipation is only 70 W, and the engineer proposes to use air at T 20C for cooling. Taking into account the increase in temperature of the air as it flows through the heat sink, plot the allowable power dissipation and the air exit temperature as a function of the air velocity over the range 1 m/s u 5 m/s, with the constraint that the base temperature not exceed Tb 70C. Properties of the air may be approximated as k 0.027 W/m K, 16.4 106 m2 /s, Pr 0.706, 1.145 kg/m3 , and cp 1007 J/kg K. Hint: Assume the air does not escape through the upper surface of the heat sink, use a correlation for internal flow, and see 11.68. 11.9