Problem 3 Helium gas at 25 °C and 4 bars is contained in a spherical glass container of 200 mm inside diameter and 10 mm thickness. If a constant stream of air is passed over the exterior of the vessel, what is the initial rate of mass loss from the container? Assume, the diffusivity of helium through the glass is 0.4 x 10-¹3 m²/s and the molar solubility of helium in the glass is 0.45 x 10³ kmol of He/(m³of solid bar of He).

In a certain manufacturing process a certain Liquid gas under 14.7 psia pressure with has a normal boiling point of -183 °C. They decided to be store this in a spherical container with 11.811 inches OD. The system is kept adiabatic by enclosing the container inside another concentric sphere of 0.45 m ID, with intervening space evacuated. Both the sphere surfaces are made of aluminum with e= 0.3. The temperature of the outer sphere is 40°C. To miminized heat gain a polished aluminum with an emissivity of 0.03 was used for container walls. Determine the percentage reduction.choices 81,90% 10.67% 83.12% 39,68% 78.56% 89.75%