Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
648039 | Applied Thermal Engineering | 2011 | 10 Pages |
Abstract
The paper presents an experimental method for the evaluation of the heat transfer coefficient of tungsten filaments at low pressures and high temperatures. For this purpose an electrode of a T5 fluorescent lamp was tested under low pressures with simultaneous heating in order to simulate the starting conditions in the lamp. It was placed in a sealed vessel in which the pressure was varied from 1Â kM (kilo micron) to 760Â kM. The voltage applied to the electrode was in the order of the filament's voltage of the lamp at the normal operation with the ballast during the preheating process. The operating frequency ranged from DC to 50Â kHz. The experiment targeted on estimating the temperature of the electrode at the end of the first and the ninth second after initiating the heating process. Next, the heat transfer coefficient was calculated at the specific experimental conditions. A mathematical model based on the results was developed that estimates the heat transfer coefficient. The experiments under different pressures confirm that the filament's temperature strongly depends on the pressure.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
N.G. Chondrakis, F.V. Topalis,