The coating has an emissivity of ε=0.7, and the temperatures of the oven and chamber walls are 175oC and 25oC, respectively. If the panel is placed in the oven at an initial temperature of 25oC and removed from the chamber at a safe-to-touch temperature of 37oC, what is the total elapsed time for the two-step curing operation?

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk