Heat treatment of metals is commonly done using electrically heated draw batch furnaces. Consider a furnace that is situated in a room with surrounding air temperature of 30°C and an average convection heat transfer coefficient of 15 W/m²∙K. The outer furnace front surface has an emissivity of 0.7, and the inside surface is subjected to a heat flux of 5 kW/m². To ensure safety and avoid thermal burn of individuals working around the furnace, the outer front surface of the furnace should be kept below 50°C. Based on the information given about the furnace, does the furnace front surface require insulation to avoid thermal burn?

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90=5 kW/m² Furnace front ε = 0.7 Tsum = 30°C surr Air, 30°C h = 15 W/m².K -To