Mavi ışık yayan diyotların ve beyaz ışık dönüşümünün termal ve optik özelliklerine dair bir inceleme

The evolution of lighting technologies has progressed from primitive fire-based sources to advanced solid-state devices, with Light-Emitting Diodes (LEDs) emerging as a cornerstone of modern illumination due to their energy efficiency and versatility. However, the performance and longevity of LEDs are critically dependent on effective thermal management, as excessive heat generation can degrade efficiency and lead to premature failure. This work examines natural convection heat transfer from millimetric surfaces using LED chip packages as a representative system. Experiments were conducted at electrical currents between 40–120 mA, measuring junction and fluid temperatures, and results were validated against CFD simulations with good agreement. Analysis revealed that conventional Nusselt number correlations deviate significantly at this scale, particularly for horizontal and vertical chip surfaces. This study examines the thermal–optical behavior of phosphor converted LEDs using experimental testing and CFD modeling. LED packages with phosphor concentrations of 0.99 wt.%, 1.3 wt.%, and 2.98 wt.% were fabricated and tested under controlled conditions. Junction temperatures and chromaticity coordinates were measured, while a validated CFD model reproduced the results. At 0.99 wt.%, the CIE coordinates were approximately (0.26, 0.21). When the phosphor loading was increased to 1.3 wt.%, the CIE coordinates shifted to about (0.3, 0.26). At the highest concentration of 2.98 wt.%, the junction temperature rose by ~1.7 °C, and the CIE coordinates changed further to around (0.43, 0.44). The agreement between experiments and simulations confirms the accuracy of the modeling approach and shows the direct relationship between phosphor loading, junction heating, and chromaticity shift. The findings underscore the importance of optimizing thermal management strategies for LEDs, particularly in high-power applications. The study contributes to the advancement of LED technology by providing insights into heat dissipation mechanisms and proposing practical solutions for enhancing optical and thermal performance for the added benefits of reliability.