A sphere 20 cm in diameter containing liquid air (??140?C) is covered with 5 cm thick glass wool (50 kg/m3 density) with an emissivity of 0.8. Estimate the rate of heat transfer to the liquid air from the surrounding air at 20?C by convection and radiation. How would you reduce the heat transfer?GIVENA sphere containing liquid air covered with glass woolSphere diameter (Ds) = 20 cm = 0.2 mLiquid air temperature (Ta) = ?? 140?C = 133 KSurrounding air temperature (T??) = 20?C = 293 KInsulation thickness (s) = 5 cm = 0.05 mInsulation emissivity (ε) = 0.8ASSUMPTIONSSteady state conditionsThe surroundings behave as a black body enclosure at T??Surrounding air is stillThermal resistance of the convection inside the sphere and of the container wall arenegligible

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S=5 cm Ta= 133 K T= 20°C = 293 K D = 0.2 m- - Liquid Air Insulation