A computational and experimental investigation of the metallisation effects on the thermal characteristics of an automotive exterior lighting lamp

This study was performed to describe the reflector metallisation effects considering the heat transfer characteristics and hot spot formation on an automotive exterior lamp. To form an accurate comparison, three reflectors were studied with emissivities of epsilon(1) = 0.04, epsilon(2) = 0.42 and epsilon(3) = 0.95, which indicated the aluminium-coated, uncoated white and uncoated black reflectors, respectively. The discussion section is organised to address the numerical evaluations using computational fluid dynamics (CFD) and the experimental evaluations. The computational results indicated that, despite the variations in h(conv) and h(rad) with epsilon, the total heat transfer coefficients on the bulb's surface result in a constant value. Additionally, it is observed that the hot spot location on the lens moves to the centre area for a lower reflector emissivity (epsilon(3)->epsilon(1)) as the radiation approaching the lens becomes more effective on the lens's temperature distribution. The numerical and experimental results are compared, and a good agreement is found between them.