Transport phenomena
Poly (vinyl chloride), PVC, is a common polymer used for fluid pipes and many consumer products, such as inflatable mattresses. It degrades at high temperatures and forms hydrochloric acid, a highly corrosive acid:
(C2113COn —, (C2112)7, + HCl
This occurs at a constant rate K, which is independent of HC1 concentration.
Consider a PVC rod of radius R that is held at high temperatures for a long time so that the concentration of HC1 reaches a steady state.
On the surface, the rod reaches equilibrium with its surroundings at a fixed HC1 concentration, CHci,s. You would like to know the concentration profile of HC1 in the rod.
a) Write the differential equation for steady state diffusion and homogeneous chemical reaction at constant reaction rate K in a cylindrical rod. Determine the solution for the HC1 concentration in the rod.
b) What is the maximum concentration of HC1? KR2 DCH c) Consider the dimensionless quantity .
How is this quantity related to the uniformity of the HC1 concentration in the rod? PVC rod