The Effect of Different Filament Arrangements on Thermal and Optical Performances of LED Bulbs

Abstract

The influences on thermal and optical performances of light emitting diode (LED) bulbs with three different filament arrangements are investigated in detail. The average junction temperature, temperature of the surface of the bulb, and luminous flux of three samples all increased with increasing power. The thermal performance test results show that between the average junction, temperature and power were linear. The junction temperatures of the three samples at a power of 3.5 W were 102.48, 98.46, and 88.88 • C. The optical performance test results revealed that the luminous flux and efficiency in the two vertical filament arrangements were closely related to each other and higher than that of the horizontal filament arrangement. A numerical model of LED filament bulbs was established by the Floefd 17.2 software for analyzing the temperature distribution of the cross section and the gas flow path inside the bulb. The simulation results illustrated that the average temperatures of three samples were 105.88, 101.83, and 96.12 • C. Additionally, the gas flow inside the bulb of the two vertical filament arrangements was subject to forming a thermal cycle during operation work more than that of the horizontal filament arrangement. As a result, the flexible spiral LED filament bulb is feasible as a new light source.

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

“…Since the surface area of the filament is very small, the thermal radiation generated by the filament is negligible. The numerical simulation model has been introduced in [9].…”

“…Solid region energy equation: ∇ ∇ (4) There are five sub-domains in the computational domain, i.e., LED chip, filament (substrate, glue and chips), bubble shell, gas vacuum inside the bulb and ambient condition. The thermal physical properties of each sub-domain were shown in (Table 1) [9], which was used to calculate the above governing equation. The LED chips were regarded as volumetric heat source with a 70%-80% efficiency of conversion into heat [9,27].…”

“…The thermal physical properties of each sub-domain were shown in (Table 1) [9], which was used to calculate the above governing equation. The LED chips were regarded as volumetric heat source with a 70%-80% efficiency of conversion into heat [9,27]. The imposed volume heat source was 2.45W, which uniformly distributed on 99 chips.…”

“…The first enemy of LED is the heat owing to the material of semiconductor [8], so the thermal management of LEDs of great value. 45% of the input electrical energy is converted into heat owing to the power conversion efficiency of LED chips is about 55% [9]. For many advanced cooling Optimum Composition of Vacuum Content in a Spiral-Like Flexible Chimney-Based LED Bulb1 systems, such as heat-pipe cooling [10], liquid cooling [11], ionic wind cooling [12][13][14], as well as heat sink cooling [15], have been used to manage the thermal property of high-power LEDs.…”

Thermal Performance of LED Filament in Flip-Chip Packaging Manufactured for Different Correlated Color Temperature

“…Light-emitting diodes (LED), an ultramodern cold light source, have the advantages of energy saving, environmental protection, long life and stable performance. Therefore, it is widely used in daily lighting, animal and plant culture and even liquid crystal display [1][2][3][4]. However, when using LEDs as everyday lighting materials, there are many aspects to pay attention to.…”