THERMAL FIELD SIMULATION OF A TUNGSTEN FILAMENT LAMP REFERRING TO ITS LIFETIME

Marcel Virág - Justín Murín

   This article deals with the calculation of the filament lifetime regarding the evaporation of tungsten mass from the filament surface. The filament of an incandescent lamp represents an electric resistor. Its resistance depends on the intensity of tungsten mass evaporation. If an electrical power is applied, it is converted to heat that causes the temperature rise in the filament. The intensity of tungsten mass evaporation depends strongly on the filament temperature. Therefore, the modelling of filament geometry and simulation of its temperature field is described as well. The finite element method (FEM) has been used for the temperature field solution. The steady temperature fields were derived in the five solution steps. Calculation of separate solutions differs with reference to the filament diameter reduction in the process of evaporation. Actually, the change of the diameter represents decreasing of the filament material (tungsten). Following this change, the assumed lamp life is evaluated subsequently. The result of the life calculation was compared with the life data listed in the work standard for 7528 car lamp produced by OSRAM that we have modelled. The temperature field obtained by FEM was compared with thermovision camera measurement.

Keywords: filament lifetime

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