Transient thermal analysis of an LED lighting device in ANSYS Workbench

Abstract

Relevance: Heat transfer in an LED lighting device depends on its construction, material properties and operating conditions. An average temperature estimate cannot fully identify local hot spots on the LED board. Evaluating the spatial temperature distribution together with its time evolution is therefore necessary to assess whether current adjustment can reduce the thermal load.

Aim: To calculate the three-dimensional transient temperature field of an LED lighting device and quantify the thermal effect of current adjustment by comparing nominal and reduced-current operating conditions.

Methods: The finite element method was applied in the Transient Thermal module of ANSYS Workbench. The model included conduction through the device components, convection to the surroundings and volumetric internal heat generation. Both operating conditions were simulated for 5400 s using the same geometry, materials and boundary conditions. A parametric analysis evaluated the dependence of maximum temperature on internal heat generation.

Results: At 5400 s, the maximum temperature of the board carrying the LEDs was 69.142 °C under nominal conditions and 63.938 °C under reduced-current conditions, giving a reduction of 5.204 °C. The difference between the maximum and minimum board temperatures decreased from 0.265 to 0.237 °C. The results showed that reducing internal heat generation can lower the board temperature.