Oil spill cleanup costs for a nation or region can be estimated by taking the average cost for the specified region and multiplying it by various “modification factors” that are a function of oil type (light crude, heavy crude, No. 4 fuel, etc.), spill size (< 34 tons, 34–340 tons, etc.), location type (offshore, nearshore, in-port), cleanup method (dispersants, burning, manual), and extent of shoreline oiling (0–1 km, 2–5 km, etc.). For an average cost of $23.3 per liter and modifiers for a region in the United States of 1.35, 0.65, 1.28, 0.25, and 1.36 for oil type, spill size, location type, cleanup method, and extent of shoreline oiling, respectively, determine the estimated cleanup cost per liter of an oil spill in the region of the United States. The cleanup cost per liter of an oil spill in the region of the United States is estimated to be $
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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?