Optimum Composition of Vacuum Content in a Spiral-Like Flexible Chimney-Based LED Bulb1

This paper introduced the gas flow and optimization of a spiral-like flexible chimneybased LED bulb by a combined mathematical and experimental study. A mathematical model of spiral flexible LED bulb considering nature convection, radiation and heat transfer was established by the FLOEFD software based on the finite element method (FEM), and was also compared with the experimental result. The effect of chimney-self based and vacuum content on the thermal performance of a bulb was studied. A thermal resistance model was proposed for analytical model. Compared with the filament with a stretch height of 3cm, the chimney effect can reduce the average junction temperature of filament by 6.38 ℃ (through the experiment) and 6.48 ℃ (through the simulation) respectively. The results revealed that the chimney effect has a huge impact on the gas flow in the bulb. The cause of the phenomenon is that flexible LED filament can improve the gas flow by changing self-shape instead of other cooling device. A vacuum content was introduced in the bulb and composition was optimized by using analytical model. The filament temperature in optimized bulb could decrease 6 0C than full filled with helium.