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The walls of an oven are made from steel sheets with insulating board between them of...

The walls of an oven are made from steel sheets with insulating board between them of thermal conductivity 0.18 J m-1 s-1 °C-1. If the maximum internal temperature in the oven is 300°C and the outside surface of the oven wall must not rise above 50°C, estimate the minimum necessary thickness of insulation assuming surface heat transfer coefficients to the air on both sides of the wall are 15 J m-2 s-1 °C-1. Assume the room air temperature outside the oven to be 25°C and that the insulating effect of the steel sheets can be neglected. [ 10.8 cm ]

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