Mass transfer model of halogen doped incandescent lamps with application to the W--O--Br system

A mass transfer model of halogen doped incandescent lamps is formulated. In this model, the transport processes occurring in these lamps are represented by diffusion and counter diffusion of gaseous species across the stagnant boundary layer surrounding the filament with simultaneous reactions at the bulb wall and the filament. The model is applied to the 500 watt-120 volt-T3 quartz halogen lamp geometry in which the initial gas phase is argon with small concentrations of oxygen and bromine. The tungsten flux from wall to filament and vice versa and, thus, the conditions of wall blackening are calculated as a function of the initial bromine and oxygen content, filament and wall temperature, total pressure and wall condensate, i.e., W(s), WO2(s), and WO3