As a designer working for a major electric appliance manufacturer, you are required to estimate the amount of fiberglass insulation packing (k = 0.035 W/m K) that is needed for a kitchen oven shown in the figure below. The fiberglass layer is to be sandwiched

between a 2-mm-thick aluminum cladding plate on the outside and a 5-mm-thick stainless steel plate on the inside that forms the core of the oven. The insulation thickness is such that the outside cladding temperature does not exceed 40°C when the temperature at the inside surface of the oven is 300°C. Also, the air temperature in the kitchen varies from 15°C to 33°C, and the average heat transfer coefficient between the outer surface of the oven and air is estimated to be 12.0 W/m² K. Determine the thickness of the fiberglass insulation that is required for these conditions. What would be the outer surface temperature when the inside surface of the oven is at 475°C?

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Fiberglass insulation