Thermodynamics HW Solutions 233

# Thermodynamics HW Solutions 233 - Chapter 15 Steady Heat...

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Chapter 15 Steady Heat Conduction 3-114 A circuit board houses 80 logic chips on one side, dissipating 0.04 W each through the back side of the board to the surrounding medium. The temperatures on the two sides of the circuit board are to be determined for the cases of no fins and 864 aluminum pin fins on the back surface. Assumptions 1 Steady operating conditions exist. 2 The temperature in the board and along the fins varies in one direction only (normal to the board). 3 All the heat generated in the chips is conducted across the circuit board, and is dissipated from the back side of the board. 4 Heat transfer from the fin tips is negligible. 5 The heat transfer coefficient is constant and uniform over the entire fin surface. 6 The thermal properties of the fins are constant. 7 The heat transfer coefficient accounts for the effect of radiation from the fins. Properties The thermal conductivities are given to be k = 20 W/m °C for the circuit board, k = 237 W/m °C for the aluminum plate and fins, and k = 1.8 W/m
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