Chapter 7 External Forced Convection7-85A cylindrical oven is to be insulated to reduce heat losses. The optimum thickness of insulation and the amount of money saved per year are to be determined. Assumptions1Steady operating conditions exist. 2 Heat transfer through the insulation is one-dimensional. 3 Thermal conductivities are constant. 4 The thermal contact resistance at the interface is negligible. 5 The surface temperature of the furnace and the heat transfer coefficient remain constant. 6 The surfaces of the cylindrical oven can be treated as plain surfaces since its diameter is greater than 1 m. PropertiesThe thermal conductivity of insulation is given to be k= 0.038 W/m⋅°C. Analysis We treat the surfaces of this cylindrical furnace as plain surfaces since its diameter is greater than 1 m, and disregard the curvature effects. The exposed surface area of the furnace is 222sidebasem69.70m)m)(65.1(2m)5.1(2222=+=+=+=πππrLrAAAo
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