Discuss the following in detail:
Q: Many laptop computers are equipped with thermal management systems that involve liquid cooling of the central processing unit (CPU), transfer of the heated liquid to the back of the laptop screen assembly, and dissipation of heat from the back of the screen assembly by way of a flat, isothermal heat spreader. The cooled liquid is re-circulated to the CPU and the process continues. Consider an aluminum heat spreader that is of width w = 275 mm and height L = 175 mm. The screen assembly is oriented at an angle 0 = 30° from the vertical direction, and the heat spreader is attached to the t = 3 mm thick plastic housing with a thermally conducting adhesive. The plastic housing has a thermal conductivity of k = 0.21 W/m · K and emissivity of B = 0.85. The contact resistance associated with the heat spreader housing interface is R"t,c = 2.0 x 10-4 m2 · K/W · If the CPU generates, on average, 15 W of thermal energy, what is the temperature of the heat spreader when T8 = Tsur = 23°C? Which thermal resistance (contact, conduction, radiation, or free convection) is the largest?