Two concentric spheres 0.2 m and 0.3 m in diam, with the space between them evacuated, are to be used to store liquid air (133 K). If the surfaces of the spheres have been flashed with aluminum and the liquid air has a talent heat of vaporization of 209 kJ/kg, determine the number of kilograms of liquid air evaporated per hour.GIVENTwo concentric spheres with the space between them evacuated and liquid air in the inner sphereDiametersD1 = 0.2 mD2 = 0.3 mLiquid air temperature (Ta) = 133 KRoom temperature (T??) = 293 KSurfaces of the spheres have been flashed with aluminumHeat of vaporization of liquid air (hfg) = 209 kJ/kg = 209,000 J/kgASSUMPTIONSSteady stateConvective thermal resistance between the liquid air and interior sphere is negligibleThermal resistance of the sphere walls is negligibleNatural convection on the exterior is negligibleThe room behaves as a blackbody enclosureThe thickness of the sphere walls innegligible

A, D = 0.2 m, T, = T = 133 K Llquld T. 293 K A2, D2 = 0.3 m A,R TA= 133 K Evacuated