One hundred electrical components each dissipating 25 W, are attached to one surface of a square (0.2 m x 0.2 m) copper plate, and all the dissipated energy is transferred to water in parallel flow over the opposite surface. A protuberance at the leading edge of the plate acts to trip the boundary layer, and the plate itself may be assumed to be isothermal. The water velocity and temperature are u∞ = 2m/s and T∞ = 17°C, and the water's thermo physical properties may be approximated as v = 0.96 X 10-6 m2/s, k = 0.620 W/m ∙ K, and Pr = 5.2.

(a) What is the temperature of the copper plate?

(b) If each component has a plate contact surface area of 1 cm 2 and the corresponding contact resistance is 2 x 10-4 m2 ∙ K/W, what is the component temperature? Neglect the temperature variation across the thickness of the copper plate.

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Copper plate, T, Contact area, A. Water and resistance, R Component, T. Boundary layer trip L= 0.2 m