Abstract
•Testing model is first proposed for examining the thermal performance of car headlamp.•Correlation between mean air temperature and key parameters is essentially revealed.•Variation of mean air temperature is very complicated and depends on many effects.
This paper describes an experimental study of the thermal performance of SMD-LED chips (surface mount device – light-emitting diodes) in modern car headlamps. For this purpose, a new test model is proposed for the first time. The effect of key parameters, such as LED powers, ambient temperatures outside the headlamp, chamber configurations with and without inner lens, and heat sink (HS) sizes, is examined. As a result, a correlation between the mean air temperature (MAT) and the key parameters is essentially revealed. Variation of MAT with the LED power supply obeys the power law regardless of the presence of the inner lens. Moreover, it is also extremely complicated and depends on many effects. The thermal resistance decreases with increasing the HS size or decreasing the volume ratio of the housing chamber to HS (Vr). A significant reduction in thermal resistance and MAT per unit of HS area is up to 67.7 % and 74 % when Vr is reduced from 64.5 to 15.8, respectively. Based on these results, a new approach to thermal management of an enclosed chamber can be developed prospectively by defining the ambient temperature as MAT.