The extent to which the tip condition affects the thermal performance of a fin depends on the fin geometry and thermal conductivity, as well as the convection coefficient. consider an alloyed aluminum (k = 180 w/m*k) rectangular fin of length l= 10 mm, thickness t = 1 mm, and width w > > t. the base temperature of the fin is tb= 100°c, and the fin is exposed to a fluid of temperature t[infinity]= 25°c. assuming a uniform convection coefficient of h = 100 w/m2*k over the entire fin surface, determine the fin heat transfer rate per unit width qf’, efficiency ηf, effectiveness εf, thermal resistance per unit width r’t, f, and the tip temperature t(l) for

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?