Gryzunova T. High temperature heat and mass transfer during chemical reactions and phase transitions on tangsten and its oxide surfaces.

An analysis was fulfilled of high temperature modes of heat and mass transfer during oxidation of tungsten filament heating by electric current. It was established that account of oxide film evaporation heat loss led to increase of critical current values corresponding to filament extinction and to decrease of oxide film thickness defining tungsten particle ignition and extinction. Critical values of electric current were defined corresponding to transitions between high temperature and low temperatures modes of oxidation. It was shown that without account of radiation heat loss a range of filament diameters existed for which a transition from high temperature mode to low temperature one by means of current diminishing was impossible. It was shown that critical values of electric current were less in case of conductor vertical positioning in comparison with horizontal positioning due to natural convection. A situation is inverse in case of forced convection. It was established that Stefan flux ledto increase of critical parameters values defining coincidence of ignition and extinction critical conditions.