Applying the Law of Diffusion to Automotive Lamp Venting

Vented automotive lamps exchange moisture with the surroundings during steady state and transient conditions. An application of Fick's Law of Diffusion gives the mass transfer rate of a vapor A through a stagnant column of gas B for steady-state conditions. Automotive lamp ventilation is similar to this simplified problem given certain assumptions and where the vapor A represents moisture in the air at one end of the vent tube and the gas B is the air in or outside the lamp. This paper shows that the equimolar counter-diffusion problem, a solution for Fick's Law, has potential in reliably predicting humidity changes within an automotive lamp for static conditions.