Liquid oxygen $($LOX$)$ is stored in a spherical vessel of OD $500$ mm $.$ The outer surface of the vessel is

at $-10C$ while the laboratory which houses the vessel is at $30C.$ The convective heat transfer

coefficient is $10\frac{W}{m^2}K$ while the outer surface has an emissivity of $0\mathrm{.}2.$ What will be the rate of

oxygen vaporisation? If the vessel is covered with $10$ mm thick insulation $(k=0\mathrm{.}0015\frac{W}{m}K$ and $=$

$0\mathrm{.}2),$ what will be the rate of LOX evaporation? $[$Oxygen has a boiling point of $90$ K and latent beat

of evaporation of $214k\frac{J}{k}g.$