A spherical vessel has an inner radius r₁ and an outer radius r₂. The inner surface (r = r₁) of the vessel is subjected to a uniform heat flux q̇₁. The outer surface (r = r₂) is exposed to convection and radiation heat transfer in a surrounding temperature of T_∞. The emissivity and the convection heat transfer coefficient on the outer surface are e and h, respectively. Express the boundary conditions and the differential equation of this heat conduction problem during steady operation.