A steam pipe has an outside diameter of 0.12 m. It is insulated with calcium silicate. The insulation is 20 mm thick. The temperature between the outer edge of the pipe and the inner radius of the insulation is maintained at 600 K. Convection and radiation are driving by a temperature of 25 degree C on the outside of the insulation. The convection heat transfer coefficient is 25 W/m^2 -K. The radiation heat transfer coefficient is 30 W/m^2-K. What is the rate of heat loss from the pipe on a per length basis? What is the temperature on the outside surface of the calcium silicate?

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?