基于LED燈具的散熱考慮

　　由于使用LED照明燈具（稱為燈具在照明業務）變得更加普遍，他們的設計師面臨的LED矛盾。雖然LED比白熾燈泡效率高得多（圖1），它們的最大允許工作溫度要低得多，而且在工作溫度限制下也很難保持。［注：可見光LED發光效率約為100流明/瓦，相比約15流明/瓦白熾燈。］在熱強度的差異部分是由于玻璃，白熾燈泡的特種金屬，陶瓷，固有可以容忍更多的熱量比LED封裝。

　　Figure 1： The luminous efficacy of LEDs （often informally confused with their efficiency） has increased dramatically over the years and is now five times to six times better than incandescent bulbs; ironically， the thermal issues and associated dissipation challenges are far more difficult for LEDs.

　　However， a large part of this difference is due to how the LED manages its own heat compared to a traditional bulb. Thermal physics shows that there are three ways for heat to travel from its source to a cooler sink：

　　Radiation， where the heat energy leaves as electromagnetic infrared waves. （Note that this is the only choice in the vacuum of space， making the cooling of spacecraft a real challenge.）

　　Conduction， where the heat travels through a solid or static liquid.

　　Convection， where the heat is carried away by a moving fluid （a gas， usually air， or a liquid in some advanced designs）.