隨著歐盟執委會明令2011年起新車必須配置「晝行燈自動照明系統」，讓行進中的汽車更容易被看見，減少事故發生的機率，因此許多車廠也相繼投入研究，但目前大部分的車輛還是以開啟近光燈當晝行燈使用，此舉雖然提高了安全性，卻也導致需頻繁的更換光源以及能源的浪費；而LED因為有著環保、體積小、耗電量少、啟動快、壽命長等優點，成為目前最適合於晝行燈之光源，但卻會因操作溫度過高而燒毀，良好的散熱設計使晝行燈能穩定工作，將是LED應用於晝行燈之重要關鍵。
有鑑於此，本文將針對LED晝行燈進行散熱設計開發，透過數值模擬分析設計出有效的解決方案，並且將所設計之一體式散熱模組透過壓鑄法製造出LED晝行燈原型，再使用恆溫箱進行實際量測，將其數據與模擬值作一比較，以探討本文所建構之模擬結果與實際量測間之誤差。模擬結果顯示在環境溫度為35oC時，LED的晶片接合點溫度為51oC，在考量熱阻及輻射下所模擬之結果其誤差也在5%以內，而在將輸入功率提升四倍後，接合點溫度則為88.6 oC，低於LED失效溫度120 oC許多。足以證明本文所建構之數值模型及模擬方法具有相當之可信度，不僅成功設計出能有效解決LED晝行燈散熱問題之方案，亦可作為後續其它以LED為光源的燈具之參考與應用。

Recently, the European Commission has ordered that all new motor vehicles be equipped with the Dedicated Daytime Running Light (DRL) from the year 2011 to enhance road safety. DRL is a special lamp; they can be automatically switched on when the engine is started, and hence substantially increase the visibility of motor vehicles. Regarding its applications in DRL, LED offers many advantages over traditional light sources. Other than its high lighting efficacy (lumens/Watt), low electricity consumption, quick response time, and long lifetime, LED is generally small in size, which provides the design of vehicle DRL greater flexibility. However, the application of high brightness LED on DRL still faces severe thermal challenge in removing the unavoidable dissipation heat, which directly influences the radiation efficiency, emitted light quality, and lifetime of LED. Therefore, this investigation focuses on the thermal management for LED Daytime Running Lamp through an integrated effort of CFD simulation, CNC mockup fabrication, and experimental verification.
At first, a comprehensive CFD simulation is executed to check the heat-removing performance of several thermal modules for identifying the best thermal design. Thereafter, this effective LED module integrated with a ZINC-AL alloy casing is fabricated via die-casting and carried out the thermal performance measurements in an isothermal chamber for experimentally validating the numerical outcomes. As a result, after taking the contact resistance and radiation into account, the comparison between numerical and experimental results indicates an acceptable deviation percentage within 5%. Also, experimental result shows that the LED junction temperature is located within the range of 50~51 °C for the case of a 2.34-Watt power input and a 35°C environmental temperature. Moreover, for a 10-Watt power input, the numerical calculation predicts that LED junction temperature is 88.6 °C, which is still well below the safety limit (120 °C). In conclusion, the accomplishment of this research offers a rigorous and systematic design scheme for the thermal management of the DRL. This design scheme has successfully produced an efficient thermal module to control the LED chip temperature below safety limit.

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