The solubility of hydrogen in a steel alloy at 80°F is given by the equation  where b = 0.0066 lbmol/ft³ psi^1/2 and P_H2 is the H₂ pressure in psi. Pure hydrogen is stored in a spherical vessel made of this steel alloy having an inside diameter of 8.0 in. and a wall thickness of 2.0 in. at an initial pressure of 200 psia. The diffusivity of H₂ in the steel alloy is 3.0 × 10⁻⁷ cm²/s. Assuming pseudo-steady-state, determine:

(a) The initial rate of mass transfer of hydrogen across the vessel wall in lbmol/s.

(b) The initial rate of pressure change inside the sphere.

(c) The time needed for the internal pressure to decrease to 50 psia. Assume that air does not diffuse in the steep alloy.

Transcribed Image Text:

CH =bPH