Steady state temperature distribution.
The goal of this exercise is to find the steady-state temperature distribution T(r) in a thick-walled spherical shell where the outer surface of the shell is exposed to a convection environment and there is no heat flux at the inner surface. The physical constants for this problem are:
1. r is the radius to the inner surface of the spherical shell.
2. R is the radius to the outer surface of the spherical shell.
3. k is the thermal conductivity of the shell's material, and k is constant throughout the spherical shell.
4. q is the volumetric rate of energy generation in the shell, and q is constant.
5. T is the temperature of the fluid surrounding the outer surface of the shell, and T is constant throughout the fluid.
6. h is the convection heat transfer coefficient for the fluid surrounding the outer surface of the shell, and h is constant over the outer surface of the shell.
Take the following steps to find the temperature distribution:
a. The heat diffusion equation is derived for three-dimensional heat transfer in the radial direction and show that the heat diffusion equation reduces to the ordinary differential equation.
b. Integrate the ordinary differential equation and show that the general form of the solution to this differential equation is T(r) = 6h e.
c. Assume there is no heat flux at the inner surface. This results in a Neumann condition, or a boundary condition of the second kind. Express this boundary condition in terms of the physical constants and the unknown constants c and d.
d. The outer surface is exposed to the convection environment. This results in a boundary condition of the third kind. Express this boundary condition in terms of the physical constants and the unknown constants c and d.
e. Take the two equations developed from the boundary conditions and solve for the two constants, c and d, in terms of the physical constants.
f. Assemble the solution for the temperature distribution T(r). The answer should be in terms of variable r and the six physical constants.