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 uoo = 2 m/s and Too = 17°C, and the water's thermophysical properties may be approximated as v = 0.96 X 10-6 m2/s, k = 0.620 W/m · K, and Pr = 5.2.
(a) Estimate the surface temperature of the fourth device located 15 mm from the leading edge of the board.
(b) Generate a plot of the surface temperature of the first four devices as a function of the free stream velocity for 5 uoo 15 m/s.
(c) What is the minimum free stream velocity if the surface temperature of the hottest device is not to exceed 80°C?